air pollution project class 6

What Causes Air Pollution?

Credit: NASA/JPL-Caltech

Air pollution happens when solid and liquid particles—called aerosols —and certain gases end up in our air. These particles and gases can be bad for the planet and for our health, so keeping track of them is important.

Where do aerosols come from?

Any particle that gets picked up into the air or is formed from chemical reactions in the air can be an aerosol. Many aerosols enter the atmosphere when we burn fossil fuels—such as coal and petroleum—and wood. These particles can come from many sources, including car exhaust, factories and even wildfires. Some of the particles and gases come directly from these sources, but others form through chemical reactions in the air.

Aerosols can come from other places, too, such as ash from an erupting volcano. Dust, pollen from plants and mold spores are also examples of aerosols.

This animation uses NASA data to show how ash from a volcano in Chile travels around the world in our atmosphere. Credit: NASA's Goddard Space Flight Center

What else causes air pollution?

Certain gases in the atmosphere can cause air pollution. For example, in cities, a gas called ozone is a major cause of air pollution. Ozone is also a greenhouse gas that can be both good and bad for our environment. It all depends where it is in Earth’s atmosphere .

Ozone high up in our atmosphere is a good thing. It helps block harmful energy from the Sun, called radiation . But, when ozone is closer to the ground, it can be really bad for our health. Ground level ozone is created when sunlight reacts with certain chemicals that come from sources of burning fossil fuels, such as factories or car exhaust.

When particles in the air combine with ozone, they create smog. Smog is a type of air pollution that looks like smoky fog and makes it difficult to see.

Smog is a type of air pollution in cities that makes it difficult to see outside. Here are images of Beijing on a clear day after a rain (left) and on a smoggy day (right). Credit: Bobak via Wikimedia Commons CC BY-SA 2.5

How does air pollution affect Earth’s climate?

Aerosols can impact how the Sun’s light hits Earth. For example, some aerosols reflect sunlight while others absorb sunlight. It depends on the color of the particle.

Dark surfaces—whether it’s a black t-shirt or a dark particle in the atmosphere—absorb the Sun's heat. Lighter-colored surfaces reflect heat from the Sun.

A white t-shirt reflects the Sun on a hot day, making you feel cooler. In the same way, light-colored particles that reflect the Sun’s light and heat away from Earth can make the global temperature cooler. Dark-colored particles that absorb the Sun’s light can make the global temperature warmer.

How does air pollution affect our health?

Breathing in polluted air can be very bad for our health. Long-term exposure to air pollution has been associated with diseases of the heart and lungs, cancers and other health problems. That’s why it’s important for us to monitor air pollution.

How is NASA monitoring air pollution?

NASA uses satellites orbiting Earth to keep an eye on air pollution. In fact, air quality forecasters use information about aerosols from NASA’s Aqua , Terra and Suomi-NPP satellites.

NASA also is developing a new instrument called the Multi-Angle Imager for Aerosols, or MAIA , to fly aboard a future spacecraft mission. MAIA will help scientists understand the size, makeup and quantity of aerosols in our air. Eventually, scientists will be able to compare this information with health records. This can help us better understand the relationship between aerosol pollution and human health.

Related NASA Missions

Russell Millner/Alamy

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How smog, soot, greenhouse gases, and other top air pollutants are affecting the planet—and your health.

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What is air pollution?

What causes air pollution, effects of air pollution, air pollution in the united states, air pollution and environmental justice, controlling air pollution, how to help reduce air pollution, how to protect your health.

Air pollution  refers to the release of pollutants into the air—pollutants that are detrimental to human health and the planet as a whole. According to the  World Health Organization (WHO) , each year, indoor and outdoor air pollution is responsible for nearly seven million deaths around the globe. Ninety-nine percent of human beings currently breathe air that exceeds the WHO’s guideline limits for pollutants, with those living in low- and middle-income countries suffering the most. In the United States, the  Clean Air Act , established in 1970, authorizes the U.S. Environmental Protection Agency (EPA) to safeguard public health by regulating the emissions of these harmful air pollutants.

“Most air pollution comes from energy use and production,” says  John Walke , director of the Clean Air team at NRDC. Driving a car on gasoline, heating a home with oil, running a power plant on  fracked gas : In each case, a fossil fuel is burned and harmful chemicals and gases are released into the air.

“We’ve made progress over the last 50 years in improving air quality in the United States, thanks to the Clean Air Act. But climate change will make it harder in the future to meet pollution standards, which are designed to  protect health ,” says Walke.

Air pollution is now the world’s fourth-largest risk factor for early death. According to the 2020  State of Global Air  report —which summarizes the latest scientific understanding of air pollution around the world—4.5 million deaths were linked to outdoor air pollution exposures in 2019, and another 2.2 million deaths were caused by indoor air pollution. The world’s most populous countries, China and India, continue to bear the highest burdens of disease.

“Despite improvements in reducing global average mortality rates from air pollution, this report also serves as a sobering reminder that the climate crisis threatens to worsen air pollution problems significantly,” explains  Vijay Limaye , senior scientist in NRDC’s Science Office. Smog, for instance, is intensified by increased heat, forming when the weather is warmer and there’s more ultraviolet radiation. In addition, climate change increases the production of allergenic air pollutants, including mold (thanks to damp conditions caused by extreme weather and increased flooding) and pollen (due to a longer pollen season). “Climate change–fueled droughts and dry conditions are also setting the stage for dangerous wildfires,” adds Limaye. “ Wildfire smoke can linger for days and pollute the air with particulate matter hundreds of miles downwind.”

The effects of air pollution on the human body vary, depending on the type of pollutant, the length and level of exposure, and other factors, including a person’s individual health risks and the cumulative impacts of multiple pollutants or stressors.

Smog and soot

These are the two most prevalent types of air pollution. Smog (sometimes referred to as ground-level ozone) occurs when emissions from combusting fossil fuels react with sunlight. Soot—a type of  particulate matter —is made up of tiny particles of chemicals, soil, smoke, dust, or allergens that are carried in the air. The sources of smog and soot are similar. “Both come from cars and trucks, factories, power plants, incinerators, engines, generally anything that combusts fossil fuels such as coal, gasoline, or natural gas,” Walke says.

Smog can irritate the eyes and throat and also damage the lungs, especially those of children, senior citizens, and people who work or exercise outdoors. It’s even worse for people who have asthma or allergies; these extra pollutants can intensify their symptoms and trigger asthma attacks. The tiniest airborne particles in soot are especially dangerous because they can penetrate the lungs and bloodstream and worsen bronchitis, lead to heart attacks, and even hasten death. In  2020, a report from Harvard’s T.H. Chan School of Public Health showed that COVID-19 mortality rates were higher in areas with more particulate matter pollution than in areas with even slightly less, showing a correlation between the virus’s deadliness and long-term exposure to air pollution. 

These findings also illuminate an important  environmental justice issue . Because highways and polluting facilities have historically been sited in or next to low-income neighborhoods and communities of color, the negative effects of this pollution have been  disproportionately experienced by the people who live in these communities.

Hazardous air pollutants

A number of air pollutants pose severe health risks and can sometimes be fatal, even in small amounts. Almost 200 of them are regulated by law; some of the most common are mercury,  lead , dioxins, and benzene. “These are also most often emitted during gas or coal combustion, incineration, or—in the case of benzene—found in gasoline,” Walke says. Benzene, classified as a carcinogen by the EPA, can cause eye, skin, and lung irritation in the short term and blood disorders in the long term. Dioxins, more typically found in food but also present in small amounts in the air, is another carcinogen that can affect the liver in the short term and harm the immune, nervous, and endocrine systems, as well as reproductive functions.  Mercury  attacks the central nervous system. In large amounts, lead can damage children’s brains and kidneys, and even minimal exposure can affect children’s IQ and ability to learn.

Another category of toxic compounds, polycyclic aromatic hydrocarbons (PAHs), are by-products of traffic exhaust and wildfire smoke. In large amounts, they have been linked to eye and lung irritation, blood and liver issues, and even cancer.  In one study , the children of mothers exposed to PAHs during pregnancy showed slower brain-processing speeds and more pronounced symptoms of ADHD.

Greenhouse gases

While these climate pollutants don’t have the direct or immediate impacts on the human body associated with other air pollutants, like smog or hazardous chemicals, they are still harmful to our health. By trapping the earth’s heat in the atmosphere, greenhouse gases lead to warmer temperatures, which in turn lead to the hallmarks of climate change: rising sea levels, more extreme weather, heat-related deaths, and the increased transmission of infectious diseases. In 2021, carbon dioxide accounted for roughly 79 percent of the country’s total greenhouse gas emissions, and methane made up more than 11 percent. “Carbon dioxide comes from combusting fossil fuels, and methane comes from natural and industrial sources, including large amounts that are released during oil and gas drilling,” Walke says. “We emit far larger amounts of carbon dioxide, but methane is significantly more potent, so it’s also very destructive.” 

Another class of greenhouse gases,  hydrofluorocarbons (HFCs) , are thousands of times more powerful than carbon dioxide in their ability to trap heat. In October 2016, more than 140 countries signed the Kigali Agreement to reduce the use of these chemicals—which are found in air conditioners and refrigerators—and develop greener alternatives over time. (The United States officially signed onto the  Kigali Agreement in 2022.)

Pollen and mold

Mold and allergens from trees, weeds, and grass are also carried in the air, are exacerbated by climate change, and can be hazardous to health. Though they aren’t regulated, they can be considered a form of air pollution. “When homes, schools, or businesses get water damage, mold can grow and produce allergenic airborne pollutants,” says Kim Knowlton, professor of environmental health sciences at Columbia University and a former NRDC scientist. “ Mold exposure can precipitate asthma attacks  or an allergic response, and some molds can even produce toxins that would be dangerous for anyone to inhale.”

Pollen allergies are worsening  because of climate change . “Lab and field studies are showing that pollen-producing plants—especially ragweed—grow larger and produce more pollen when you increase the amount of carbon dioxide that they grow in,” Knowlton says. “Climate change also extends the pollen production season, and some studies are beginning to suggest that ragweed pollen itself might be becoming a more potent allergen.” If so, more people will suffer runny noses, fevers, itchy eyes, and other symptoms. “And for people with allergies and asthma, pollen peaks can precipitate asthma attacks, which are far more serious and can be life-threatening.”

More than one in three U.S. residents—120 million people—live in counties with unhealthy levels of air pollution, according to the  2023  State of the Air  report by the American Lung Association (ALA). Since the annual report was first published, in 2000, its findings have shown how the Clean Air Act has been able to reduce harmful emissions from transportation, power plants, and manufacturing.

Recent findings, however, reflect how climate change–fueled wildfires and extreme heat are adding to the challenges of protecting public health. The latest report—which focuses on ozone, year-round particle pollution, and short-term particle pollution—also finds that people of color are 61 percent more likely than white people to live in a county with a failing grade in at least one of those categories, and three times more likely to live in a county that fails in all three.

In rankings for each of the three pollution categories covered by the ALA report, California cities occupy the top three slots (i.e., were highest in pollution), despite progress that the Golden State has made in reducing air pollution emissions in the past half century. At the other end of the spectrum, these cities consistently rank among the country’s best for air quality: Burlington, Vermont; Honolulu; and Wilmington, North Carolina. 

No one wants to live next door to an incinerator, oil refinery, port, toxic waste dump, or other polluting site. Yet millions of people around the world do, and this puts them at a much higher risk for respiratory disease, cardiovascular disease, neurological damage, cancer, and death. In the United States, people of color are 1.5 times more likely than whites to live in areas with poor air quality, according to the ALA.

Historically, racist zoning policies and discriminatory lending practices known as  redlining  have combined to keep polluting industries and car-choked highways away from white neighborhoods and have turned communities of color—especially low-income and working-class communities of color—into sacrifice zones, where residents are forced to breathe dirty air and suffer the many health problems associated with it. In addition to the increased health risks that come from living in such places, the polluted air can economically harm residents in the form of missed workdays and higher medical costs.

Environmental racism isn't limited to cities and industrial areas. Outdoor laborers, including the estimated three million migrant and seasonal farmworkers in the United States, are among the most vulnerable to air pollution—and they’re also among the least equipped, politically, to pressure employers and lawmakers to affirm their right to breathe clean air.

Recently,  cumulative impact mapping , which uses data on environmental conditions and demographics, has been able to show how some communities are overburdened with layers of issues, like high levels of poverty, unemployment, and pollution. Tools like the  Environmental Justice Screening Method  and the EPA’s  EJScreen  provide evidence of what many environmental justice communities have been explaining for decades: that we need land use and public health reforms to ensure that vulnerable areas are not overburdened and that the people who need resources the most are receiving them.

In the United States, the  Clean Air Act  has been a crucial tool for reducing air pollution since its passage in 1970, although fossil fuel interests aided by industry-friendly lawmakers have frequently attempted to  weaken its many protections. Ensuring that this bedrock environmental law remains intact and properly enforced will always be key to maintaining and improving our air quality.

But the best, most effective way to control air pollution is to speed up our transition to cleaner fuels and industrial processes. By switching over to renewable energy sources (such as wind and solar power), maximizing fuel efficiency in our vehicles, and replacing more and more of our gasoline-powered cars and trucks with electric versions, we'll be limiting air pollution at its source while also curbing the global warming that heightens so many of its worst health impacts.

And what about the economic costs of controlling air pollution? According to a report on the Clean Air Act commissioned by NRDC, the annual  benefits of cleaner air  are up to 32 times greater than the cost of clean air regulations. Those benefits include up to 370,000 avoided premature deaths, 189,000 fewer hospital admissions for cardiac and respiratory illnesses, and net economic benefits of up to $3.8 trillion for the U.S. economy every year.

“The less gasoline we burn, the better we’re doing to reduce air pollution and the harmful effects of climate change,” Walke explains. “Make good choices about transportation. When you can, ride a bike, walk, or take public transportation. For driving, choose a car that gets better miles per gallon of gas or  buy an electric car .” You can also investigate your power provider options—you may be able to request that your electricity be supplied by wind or solar. Buying your food locally cuts down on the fossil fuels burned in trucking or flying food in from across the world. And most important: “Support leaders who push for clean air and water and responsible steps on climate change,” Walke says.

• “When you see in the news or hear on the weather report that pollution levels are high, it may be useful to limit the time when children go outside or you go for a jog,” Walke says. Generally, ozone levels tend to be lower in the morning.
• If you exercise outside, stay as far as you can from heavily trafficked roads. Then shower and wash your clothes to remove fine particles.
• The air may look clear, but that doesn’t mean it’s pollution free. Utilize tools like the EPA’s air pollution monitor,  AirNow , to get the latest conditions. If the air quality is bad, stay inside with the windows closed.
• If you live or work in an area that’s prone to wildfires,  stay away from the harmful smoke  as much as you’re able. Consider keeping a small stock of masks to wear when conditions are poor. The most ideal masks for smoke particles will be labelled “NIOSH” (which stands for National Institute for Occupational Safety and Health) and have either “N95” or “P100” printed on it.
• If you’re using an air conditioner while outdoor pollution conditions are bad, use the recirculating setting to limit the amount of polluted air that gets inside. 

This story was originally published on November 1, 2016, and has been updated with new information and links.

This NRDC.org story is available for online republication by news media outlets or nonprofits under these conditions: The writer(s) must be credited with a byline; you must note prominently that the story was originally published by NRDC.org and link to the original; the story cannot be edited (beyond simple things such as grammar); you can’t resell the story in any form or grant republishing rights to other outlets; you can’t republish our material wholesale or automatically—you need to select stories individually; you can’t republish the photos or graphics on our site without specific permission; you should drop us a note to let us know when you’ve used one of our stories.

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Lesson Plans, Teacher Guides and Online Environmental Resources for Educators

Find an array of environmental and science based lesson plans, activities and ideas below from EPA, other federal agencies and external organizations.  ​ Encontrar recursos para estudiantes y maestros.

Topics: Air | Climate Change | Ecosystems | Energy | Health | Waste | Water

Acid Rain: A Teacher's Guide   (PDF 56 pp, 4.6 MB) Lesson plan and activities from EPA for teachers on acid rain. Grades: 6-8 Type of Resource: Lesson plan

Acid Rain Student Pages Find the acid rain student pages, as well as general information for older students or adults. Grades: K-12 Type of Resource: Lesson plans and experiments

AIRNOW Get up-to-the-minute information about air pollution in your community, through a joint project from EPA, the National Oceanic and Atmospheric Administration, the National Park Service and other partners. The AIRNOW website includes maps, forecasts, and information about the health effects of air pollution. Grades: 9-12 Type of Resource: Website

AIRNOW Air Quality Resources  Find air quality curriculum materials and activities from AIRNOW, including a toolkit and workshop opportunities for teachers. Grades: K-8 Type of Resource: Curriculum guide

Measuring Air Quality Improvements from Vegetative Barriers This unit has been designed by EPA as a teaching aid on the topic of air quality; particularly, investigating the role vegetative barriers play in improving air quality for surrounding areas. Grades: K-5 Type of Resource: Lesson Plan

Carl Gets Some Rest (PDF 12 pp, 765 KB) This EPA coloring and story book, for children in pre-school through 2nd grade, teaches a simple lesson: there are many transportation alternatives to using a car. Grades: K-2 Type of Resource: Coloring Book

Creating Healthy Indoor Air Quality in Schools This EPA page provides information on indoor air quality in school buildings and how to order the Tools for Schools Action Kit. The kit shows how to carry out a practical plan of action to improve indoor air quality at little or no cost using common-sense activities and in-house staff. Grades: K-12 Type of Resource: Toolkit

EnviroAtlas Educational Materials These ready-made lesson plans can be used in formal and informal education settings and are aligned with Next Generation and State Science Standards. Grades: K-12 Type of Resource: Lesson Plans

Noise Pollution for Kids   (PDF 15 pp, 6.54 MB) This EPA booklet for your students will teach you how to identify which sounds are loud and ways to protect your hearing and health. Grades: K-5 Type of Resource: Activity book

Particulate Matter (PM) Air Sensor Kits Particle pollution known as particulate matter (PM) is one of the major air pollutants regulated by EPA to protect public health and the environment. A PM air sensor kit has been developed by EPA researchers as an educational tool to teach children about air quality and air science. Grades: 5-12 Type of Resource: Hands-on activity guide

Basic Ozone Layer Science Find a straightforward explanation of the ozone layer and ozone depletion. Grades: 9-12 Type of Resource: Website

AIRNOW's Ozone: Good Up High, Bad Nearby (PDF 4 pp) Ozone acts as a protective layer high above the Earth, but it can be harmful to breathe. This publication provides basic information about ground-level and high-altitude ozone. Grades:6-12 Type of Resource: Booklet/Brochure

Plain English Guide to the Clean Air Act A brief introduction to the 1990 version of the Clean Air Act, to help you understand what is in the law and how it may affect you. Grades: 9-12 Type of Resource: Booklet

RadTown USA EPA's RadTown USA is a virtual community that aims to educate students about the sources of radiation in our daily lives. Grades: 9-12 Type of Resource: Virtual activity

Teaching Kids to Conserve Energy at Home: Resources for K-12 teachers and parents This 11-minute presentation focuses on an introduction to energy and the environment, energy saving tips, how to use the Energy Star home energy yardstick, and homework ideas. Grades: K-12 Type of Resource: Video

Village Green Project These lessons provide a unique opportunity for students to learn about air quality as it relates to various topics of science appropriate to their grade level. The purpose of these lessons is to engage students of varying ability levels through hands-on and minds-on thinking. Each lesson is designed to focus around the topic of air quality; from issues of human health to career and 21st century skills. Grades: K-8 Type of Resource: Lesson Plan (PDF)  (52 pp)

Lea en español:  ¿Por qué Coco es de color naranja?

Why is Coco Orange? Coco has a problem. He is a chameleon, but he cannot change colors, and his asthma is acting up. Read how Coco and his friends at Lizard Lick Elementary solve this mystery as they learn about air quality and how to stay healthy when the air quality is bad. Grades: Pre K-2 Type of Resource: Book

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NOAA's Education Resources Website Explore this site to find the information you need to teach students about weather, climate change, and oceans. You'll find activities, background information, and much more! Grades: 6-12

National Park Service Education Resources Classroom materials, field trip opportunities and professional development programs for educators from the National Park Service. Grades: All

Climate and Health Lesson Plan and Toolkit by The American Public Health Association This lesson adopts materials developed by the National Institute for Environmental Health Sciences (NIH) to make it easy for public health professionals to guest teach at local high schools. For more resources aimed directly at teachers, see Climate Change and Human Health Lesson Plans by NIH. Grades: 9-12

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ENCYCLOPEDIC ENTRY

Air pollution.

Air pollution consists of chemicals or particles in the air that can harm the health of humans, animals, and plants. It also damages buildings.

Biology, Ecology, Earth Science, Geography

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Air pollution consists of chemicals or particles in the air that can harm the health of humans, animals, and plants. It also damages buildings. Pollutants in the air take many forms. They can be gases , solid particles, or liquid droplets. Sources of Air Pollution Pollution enters the Earth's atmosphere in many different ways. Most air pollution is created by people, taking the form of emissions from factories, cars, planes, or aerosol cans . Second-hand cigarette smoke is also considered air pollution. These man-made sources of pollution are called anthropogenic sources . Some types of air pollution, such as smoke from wildfires or ash from volcanoes , occur naturally. These are called natural sources . Air pollution is most common in large cities where emissions from many different sources are concentrated . Sometimes, mountains or tall buildings prevent air pollution from spreading out. This air pollution often appears as a cloud making the air murky. It is called smog . The word "smog" comes from combining the words "smoke" and " fog ." Large cities in poor and developing nations tend to have more air pollution than cities in developed nations. According to the World Health Organization (WHO) , some of the worlds most polluted cities are Karachi, Pakistan; New Delhi, India; Beijing, China; Lima, Peru; and Cairo, Egypt. However, many developed nations also have air pollution problems. Los Angeles, California, is nicknamed Smog City. Indoor Air Pollution Air pollution is usually thought of as smoke from large factories or exhaust from vehicles. But there are many types of indoor air pollution as well. Heating a house by burning substances such as kerosene , wood, and coal can contaminate the air inside the house. Ash and smoke make breathing difficult, and they can stick to walls, food, and clothing. Naturally-occurring radon gas, a cancer -causing material, can also build up in homes. Radon is released through the surface of the Earth. Inexpensive systems installed by professionals can reduce radon levels. Some construction materials, including insulation , are also dangerous to people's health. In addition, ventilation , or air movement, in homes and rooms can lead to the spread of toxic mold . A single colony of mold may exist in a damp, cool place in a house, such as between walls. The mold's spores enter the air and spread throughout the house. People can become sick from breathing in the spores. Effects On Humans People experience a wide range of health effects from being exposed to air pollution. Effects can be broken down into short-term effects and long-term effects . Short-term effects, which are temporary , include illnesses such as pneumonia or bronchitis . They also include discomfort such as irritation to the nose, throat, eyes, or skin. Air pollution can also cause headaches, dizziness, and nausea . Bad smells made by factories, garbage , or sewer systems are considered air pollution, too. These odors are less serious but still unpleasant . Long-term effects of air pollution can last for years or for an entire lifetime. They can even lead to a person's death. Long-term health effects from air pollution include heart disease , lung cancer, and respiratory diseases such as emphysema . Air pollution can also cause long-term damage to people's nerves , brain, kidneys , liver , and other organs. Some scientists suspect air pollutants cause birth defects . Nearly 2.5 million people die worldwide each year from the effects of outdoor or indoor air pollution. People react differently to different types of air pollution. Young children and older adults, whose immune systems tend to be weaker, are often more sensitive to pollution. Conditions such as asthma , heart disease, and lung disease can be made worse by exposure to air pollution. The length of exposure and amount and type of pollutants are also factors. Effects On The Environment Like people, animals, and plants, entire ecosystems can suffer effects from air pollution. Haze , like smog, is a visible type of air pollution that obscures shapes and colors. Hazy air pollution can even muffle sounds. Air pollution particles eventually fall back to Earth. Air pollution can directly contaminate the surface of bodies of water and soil . This can kill crops or reduce their yield . It can kill young trees and other plants. Sulfur dioxide and nitrogen oxide particles in the air, can create acid rain when they mix with water and oxygen in the atmosphere. These air pollutants come mostly from coal-fired power plants and motor vehicles . When acid rain falls to Earth, it damages plants by changing soil composition ; degrades water quality in rivers, lakes and streams; damages crops; and can cause buildings and monuments to decay . Like humans, animals can suffer health effects from exposure to air pollution. Birth defects, diseases, and lower reproductive rates have all been attributed to air pollution. Global Warming Global warming is an environmental phenomenon caused by natural and anthropogenic air pollution. It refers to rising air and ocean temperatures around the world. This temperature rise is at least partially caused by an increase in the amount of greenhouse gases in the atmosphere. Greenhouse gases trap heat energy in the Earths atmosphere. (Usually, more of Earths heat escapes into space.) Carbon dioxide is a greenhouse gas that has had the biggest effect on global warming. Carbon dioxide is emitted into the atmosphere by burning fossil fuels (coal, gasoline , and natural gas ). Humans have come to rely on fossil fuels to power cars and planes, heat homes, and run factories. Doing these things pollutes the air with carbon dioxide. Other greenhouse gases emitted by natural and artificial sources also include methane , nitrous oxide , and fluorinated gases. Methane is a major emission from coal plants and agricultural processes. Nitrous oxide is a common emission from industrial factories, agriculture, and the burning of fossil fuels in cars. Fluorinated gases, such as hydrofluorocarbons , are emitted by industry. Fluorinated gases are often used instead of gases such as chlorofluorocarbons (CFCs). CFCs have been outlawed in many places because they deplete the ozone layer . Worldwide, many countries have taken steps to reduce or limit greenhouse gas emissions to combat global warming. The Kyoto Protocol , first adopted in Kyoto, Japan, in 1997, is an agreement between 183 countries that they will work to reduce their carbon dioxide emissions. The United States has not signed that treaty . Regulation In addition to the international Kyoto Protocol, most developed nations have adopted laws to regulate emissions and reduce air pollution. In the United States, debate is under way about a system called cap and trade to limit emissions. This system would cap, or place a limit, on the amount of pollution a company is allowed. Companies that exceeded their cap would have to pay. Companies that polluted less than their cap could trade or sell their remaining pollution allowance to other companies. Cap and trade would essentially pay companies to limit pollution. In 2006 the World Health Organization issued new Air Quality Guidelines. The WHOs guidelines are tougher than most individual countries existing guidelines. The WHO guidelines aim to reduce air pollution-related deaths by 15 percent a year. Reduction Anybody can take steps to reduce air pollution. Millions of people every day make simple changes in their lives to do this. Taking public transportation instead of driving a car, or riding a bike instead of traveling in carbon dioxide-emitting vehicles are a couple of ways to reduce air pollution. Avoiding aerosol cans, recycling yard trimmings instead of burning them, and not smoking cigarettes are others.

Downwinders The United States conducted tests of nuclear weapons at the Nevada Test Site in southern Nevada in the 1950s. These tests sent invisible radioactive particles into the atmosphere. These air pollution particles traveled with wind currents, eventually falling to Earth, sometimes hundreds of miles away in states including Idaho, Utah, Arizona, and Washington. These areas were considered to be "downwind" from the Nevada Test Site. Decades later, people living in those downwind areascalled "downwinders"began developing cancer at above-normal rates. In 1990, the U.S. government passed the Radiation Exposure Compensation Act. This law entitles some downwinders to payments of $50,000.

Greenhouse Gases There are five major greenhouse gases in Earth's atmosphere.

• water vapor
• carbon dioxide
• nitrous oxide

London Smog What has come to be known as the London Smog of 1952, or the Great Smog of 1952, was a four-day incident that sickened 100,000 people and caused as many as 12,000 deaths. Very cold weather in December 1952 led residents of London, England, to burn more coal to keep warm. Smoke and other pollutants became trapped by a thick fog that settled over the city. The polluted fog became so thick that people could only see a few meters in front of them.

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by Chris Woodford . Last updated: November 22, 2022.

Photo: Air pollution is obvious when it pours from a smokestack (chimney), but it's not always so easy to spot. This is an old photo of the kind of smoke that used to come from coal-fired power plants and, apart from soot (unburned carbon particles), its pollutants include sulfur dioxide and the greenhouse gas carbon dioxide. Thanks to tougher pollution controls, modern power plants produce only a fraction as much pollution. Modern pollution made by traffic consists of gases like nitrogen dioxide and "particulates" (microscopic soot and dust fragments) that are largely invisible.

What is air pollution?

Air pollution is a gas (or a liquid or solid dispersed through ordinary air) released in a big enough quantity to harm the health of people or other animals, kill plants or stop them growing properly, damage or disrupt some other aspect of the environment (such as making buildings crumble), or cause some other kind of nuisance (reduced visibility, perhaps, or an unpleasant odor).

Natural air pollution

Photo: Forest fires are a completely natural cause of air pollution. We'll never be able to prevent them breaking out or stop the pollution they cause; our best hope is to manage forests, where we can, so fires don't spread. Ironically, that can mean deliberately burning areas of forest, as shown here, to create firebreaks. Forests are also deliberately burned to regenerate ecosystems. Photo by courtesy of US Fish and Wildlife Service .

Top-ten kinds of air pollution Photo: Flying molecules—if you could see air pollution close up, this is what it would look like. Image courtesy of US Department of Energy. Any gas could qualify as pollution if it reached a high enough concentration to do harm. Theoretically, that means there are dozens of different pollution gases. It's important to note that not all the things we think of as pollution are gases: some are aerosols (liquids or solids dispersed through gases). In practice, about ten different substances cause most concern: Sulfur dioxide : Coal, petroleum, and other fuels are often impure and contain sulfur as well as organic (carbon-based) compounds. When sulfur (spelled "sulphur" in some countries) burns with oxygen from the air, sulfur dioxide (SO 2 ) is produced. Coal-fired power plants are the world's biggest source of sulfur-dioxide air pollution, which contributes to smog, acid rain, and health problems that include lung disease. [5] Large amounts of sulfur dioxide are also produced by ships, which use dirtier diesel fuel than cars and trucks. [6] Carbon monoxide : This highly dangerous gas forms when fuels have too little oxygen to burn completely. It spews out in car exhausts and it can also build up to dangerous levels inside your home if you have a poorly maintained gas boiler , stove, or fuel-burning appliance. (Always fit a carbon monoxide detector if you burn fuels indoors.) [7] Carbon dioxide : This gas is central to everyday life and isn't normally considered a pollutant: we all produce it when we breathe out and plants such as crops and trees need to "breathe" it in to grow. However, carbon dioxide is also a greenhouse gas released by engines and power plants. Since the beginning of the Industrial Revolution, it's been building up in Earth's atmosphere and contributing to the problem of global warming and climate change . [8] Nitrogen oxides : Nitrogen dioxide (NO 2 ) and nitrogen oxide (NO) are pollutants produced as an indirect result of combustion, when nitrogen and oxygen from the air react together. Nitrogen oxide pollution comes from vehicle engines and power plants, and plays an important role in the formation of acid rain, ozone and smog. Nitrogen oxides are also "indirect greenhouse gases" (they contribute to global warming by producing ozone, which is a greenhouse gas). [9] Volatile organic compounds (VOCs) : These carbon-based (organic) chemicals evaporate easily at ordinary temperatures and pressures, so they readily become gases. That's precisely why they're used as solvents in many different household chemicals such as paints , waxes, and varnishes. Unfortunately, they're also a form of air pollution: they're believed to have long-term (chronic) effects on people's health and they play a role in the formation of ozone and smog. VOCs are also released by tobacco smoke and wildfires. [10] Particulates : There are many different kinds of particulates, from black soot in diesel exhaust to dust and organic matter from the desert. Airborne liquid droplets from farm pollution also count as particulates. Particulates of different sizes are often referred to by the letters PM followed by a number, so PM 10 means soot particles of less than 10 microns (10 millionths of a meter or 10µm in diameter, roughly 10 times thinner than a thick human hair). The smaller ("finer") the particulates, the deeper they travel into our lungs and the more dangerous they are. PM 2.5 particulates are much more dangerous (they're less than 2.5 millionths of a meter or about 40 times thinner than a typical hair). In cities, most particulates come from traffic fumes. [11] Ozone : Also called trioxygen, this is a type of oxygen gas whose molecules are made from three oxygen atoms joined together (so it has the chemical formula O 3 ), instead of just the two atoms in conventional oxygen (O 2 ). In the stratosphere (upper atmosphere), a band of ozone ("the ozone layer") protects us by screening out harmful ultraviolet radiation (high-energy blue light) beaming down from the Sun. At ground level, it's a toxic pollutant that can damage health. It forms when sunlight strikes a cocktail of other pollution and is a key ingredient of smog (see box below). [12] Chlorofluorocarbons (CFCs) : Once thought to be harmless, these gases were widely used in refrigerators and aerosol cans until it was discovered that they damaged Earth's ozone layer. We discuss this in more detail down below. [13] Unburned hydrocarbons : Petroleum and other fuels are made of organic compounds based on chains of carbon and hydrogen atoms. When they burn properly, they're completely converted into harmless carbon dioxide and water ; when they burn incompletely, they can release carbon monoxide or float into the air in their unburned form, contributing to smog. Lead and heavy metals : Lead and other toxic "heavy metals" can be spread into the air either as toxic compounds or as aerosols (when solids or liquids are dispersed through gases and carried through the air by them) in such things as exhaust fumes and the fly ash (contaminated waste dust) from incinerator smokestacks. [14] What are the causes of air pollution?

Photo: Even in the age of electric cars, traffic remains a major cause of air pollution. Photo by Warren Gretz courtesy of US DOE National Renewable Energy Laboratory (NREL) (NREL photo id#46361).

Photo: Brown smog lingers over Denver, Colorado. Photo by Warren Gretz courtesy of US DOE National Renewable Energy Laboratory (NREL) (NREL photo id#56919).

Chart: Most of the world's major cities routinely exceed World Health Organization (WHO) air pollution guidelines, though progress is being made: you can see that the 2022 figures (green) show a marked improvement on the 2016 ones (orange) in almost every case. This chart compares annual mean PM 2.5 levels in 12 representative cities around the world with the recently revised (2021) WHO guideline value of 5μg per cubic meter (dotted line). PM 2.5 particulates are those smaller than 2.5 microns and believed to be most closely linked with adverse health effects. For more about this chart and the data sources used, see note [22] .

Photo: Smokestacks billowing pollution over Moscow, Russia in 1994. Factory pollution is much less of a problem than it used to be in the world's "richer" countries—partly because a lot of their industry has been exported to nations such as China, India, and Mexico. Photo by Roger Taylor courtesy of US DOE National Renewable Energy Laboratory (NREL) .

What effects does air pollution have?

Photo: Air pollution can cause a variety of lung diseases and other respiratory problems. This chest X ray shows a lung disease called emphysema in the patient's left lung. A variety of things can cause it, including smoking and exposure to air pollution. Photo courtesy of National Heart, Lung and Blood Institute (NHLBI) and National Institutes of Health.

" In 2016, 91% of the world population was living in places where the WHO air quality guidelines levels were not met." World Health Organization , 2018

Photo: For many years, the stonework on the Parthenon in Athens, Greece has been blackened by particulates from traffic pollution, but other sources of pollution, such as wood-burning stoves, are increasingly significant. Photo by Michael M. Reddy courtesy of U.S. Geological Survey .

How air pollution works on different scales

Indoor air pollution.

Photo: Air freshener—or air polluter?

Further reading

Acid rain—a closer look.

Photo: Acid rain can turn lakes so acidic that fish no longer survive. Picture courtesy of U.S. Fish and Wildlife Service Division of Public Affairs. Why does that matter? Pure water is neither acidic nor alkaline but completely neutral (we say it has an acidity level or pH of 7.0). Ordinary rainwater is a little bit more acidic than this with about the same acidity as bananas (roughly pH 5.5), but if rain falls through sulfur dioxide pollution it can turn much more acidic (with a pH of 4.5 or lower, which is the same acidity as orange or lemon juice). When acid rain accumulates in lakes or rivers, it gradually turns the entire water more acidic. That's a real problem because fish thrive only in water that is neutral or slightly acidic (typically with a pH of 6.5–7.0). Once the acidity drops below about pH 6.0, fish soon start to die—and if the pH drops to about 4.0 or less, all the fish will be killed. Acid rain has caused major problems in lakes throughout North America and Europe. It also causes the death of forests, reduces the fertility of soil, and damages buildings by eating away stonework (the marble on the US Capitol in Washington, DC has been eroded by acid-rain, for example). One of the biggest difficulties in tackling acid rain is that it can happen over very long distances. In one notable case, sulfur dioxide air pollution produced by power plants in the UK was blamed for causing acid rain that fell on Scandinavian countries such as Norway, producing widespread damage to forests and the deaths of thousands of fish in acidified lakes. The British government refused to acknowledge the problem and that was partly why the UK became known as the "dirty man of Europe" in the 1980s and 1990s. [18] Acid rain was a particular problem in the last 30–40 years of the 20th century. Thanks to the decline in coal-fired power plants, and the sulfur dioxide they spewed out, it's less of a problem for western countries today. But it's still a big issue in places like India, where coal remains a major source of energy. Global air pollution It's hard to imagine doing anything so dramatic and serious that it would damage our entire, enormous planet—but, remarkable though it may seem, we all do things like this everyday, contributing to problems such as global warming and the damage to the ozone layer (two separate issues that are often confused). Global warming Every time you ride in a car, turn on the lights, switch on your TV , take a shower, microwave a meal, or use energy that's come from burning a fossil fuel such as oil, coal, or natural gas, you're almost certainly adding to the problem of global warming and climate change: unless it's been produced in some environmentally friendly way, the energy you're using has most likely released carbon dioxide gas into the air. While it's not an obvious pollutant, carbon dioxide has gradually built up in the atmosphere, along with other chemicals known as greenhouse gases . Together, these gases act a bit like a blanket surrounding our planet that is slowly making the mean global temperature rise, causing the climate (the long-term pattern of our weather) to change, and producing a variety of different effects on the natural world, including rising sea levels. Read more in our main article about global warming and climate change . Ozone holes

How can we solve the problem of air pollution?

Photo: Pollution solution: an electrostatic smoke precipitator helps to prevent air pollution from this smokestack at the McNeil biomass power plant in Burlington, VT. Photo by Warren Gretz courtesy of US DOE National Renewable Energy Laboratory (NREL).

What can you do to help reduce air pollution?

Photo: Buying organic food reduces the use of sprayed pesticides and other chemicals, so it helps to reduce air (as well as water) pollution.

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Find out more, on this site.

• Climate change and global warming
• Environmentalism (introduction)
• Land pollution
• Organic food and farming
• Renewable energy
• Water pollution

• Breathless: Why Air Pollution Matters—and How it Affects You by Chris Woodford. Icon, 2021. My new book explores the problem in much more depth than I've been able to go into here. You can also read a bonus chapter called Angels with dirty faces: How air pollution blackens our buildings and monuments .
• The Invisible Killer: The Rising Global Threat of Air Pollution and How We Can Fight Back by Gary Fuller. Melville House, 2018.
• Reducing Pollution and Waste by Jen Green. Raintree/Capstone, 2011. A 48-page introduction for ages 9–12. The emphasis here is on getting children to think about pollution: where it comes from, who makes it, and who should solve the problem.
• Pollution Crisis by Russ Parker. Rosen, 2009. A 32-page guide for ages 8–10. It starts with a global survey of the problem; looks at air, water, and land pollution; then considers how we all need to be part of the solution.
• Earth Matters by Lynn Dicks et al. Dorling Kindersley, 2008. This isn't specifically about pollution. Instead, it explores how a range of different environmental problems are testing life to the limit in the planet's major biomes (oceans, forests, and so on). I wrote the section of this book that covers the polar regions.
• State of Global Air : One of the best sources of global air pollution data.
• American Lung Association: State of the Air Report : A good source of data about the United States.
• European Environment Agency: Air quality in Europe : A definitive overview of the situation in the European countries.
• World Health Organization (WHO) Ambient (outdoor) air pollution in cities database : A spreadsheet of pollution data for most major cities in the world (a little out of date, but a new version is expected soon).
• Our World in Data : Accessible guides to global data from Oxford University.
• The New York Times Topics: Air Pollution
• The Guardian: Pollution
• Wired: Pollution
• 'Invisible killer': fossil fuels caused 8.7m deaths globally in 2018, research finds by Oliver Milman. The Guardian, February 9, 2021. Pollution of various kinds causes something like one in five of all deaths.
• Millions of masks distributed to students in 'gas chamber' Delhi : BBC News, 1 November 2019.
• 90% of world's children are breathing toxic air, WHO study finds by Matthew Taylor. The Guardian, October 29, 2018. The air pollution affecting billions of children could continue to harm their health throughout their lives.
• Pollution May Dim Thinking Skills, Study in China Suggests by Mike Ives. The New York Times, August 29, 2018. Long-term exposure to air pollution seems to cause a decline in cognitive skills.
• Global pollution kills 9m a year and threatens 'survival of human societies' by Damian Carrington. The Guardian, October 19, 2017. Air, water, and land pollution kill millions, cost trillions, and threaten the very survival of humankind, a new study reveals.
• India's Air Pollution Rivals China's as World's Deadliest by Geeta Anand. The New York Times, February 14, 2017. High levels of pollution could be killing 1.1 million Indians each year.
• More Than 9 in 10 People Breathe Bad Air, WHO Study Says by Mike Ives. The New York Times, September 27, 2016. New WHO figures suggest the vast majority of us are compromising our health by breathing bad air.
• Study Links 6.5 Million Deaths Each Year to Air Pollution by Stanley Reed. The New York Times, June 26, 2016. Air pollution deaths are far greater than previously supposed according to a new study by the International Energy Agency.
• UK air pollution 'linked to 40,000 early deaths a year' by Michelle Roberts, BBC News, February 23, 2016. Diesel engines, cigarette smoke, and even air fresheners are among the causes of premature death from air pollution.
• This Wearable Detects Pollution to Build Air Quality Maps in Real Time by Davey Alba. Wired, November 19, 2014. A wearable pollution gadget lets people track their exposure to air pollution through a smartphone app.
• Air pollution and public health: emerging hazards and improved understanding of risk by Frank J. Kelly and Julia C. Fussell, Environmental Geochemistry and Health, 2015
• Health effects of fine particulate air pollution: lines that connect by C.A. Pope and D.W. Dockery. Journal of the Air and Waste Management Association, 2006
• Ambient and household air pollution: complex triggers of disease by Stephen A. Farmer et al, Am J Physiol Heart Circ Physiol, 2014

Text copyright © Chris Woodford 2010, 2022. All rights reserved. Full copyright notice and terms of use .

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Taking It to the Class: Green Projects for the Classroom

Try these great lesson ideas for environmentally conscious teachers (and their lucky students).

An annual celebration of Earth Day should not be the only time during the school year when you devote significant classroom time to exploring issues of environmental awareness and stewardship. Whether you teach biology, history, or language arts, the Web is a rich and ever-growing resource, with curriculum ideas for integrating environmental issues into lesson plans. But where to begin? That will be your decision, but we'll help you get started.

We've compiled a cross section of lessons, with ideas for every grade level. Some can be completed within a single class period and others require more time, but all are sure to get your students -- and you -- thinking about what can be done to preserve our increasingly fragile planet.

Elementary School

The life history of "stuff".

By tracing the origins of everyday products -- the bikes they ride to school or their favorite sneakers -- students develop an understanding of the impact that the production, sale, and disposal of commonly used goods have on the environment.

Though no single lesson is likely to change students' consumption patterns completely, this one is sure to get them thinking about alternatives, like wearing shoes until they're outgrown or worn out, or donating still-usable items so they don't end up in a landfill prematurely.

Topics: Consumption, Waste Production Teaching Level: Grades 2-3 Source: Education for Sustainable Development

Credit: Veer

From Farm to Table

Students (and adults, too) know surprisingly little about the origin of the food they eat every day. In this lesson, students compile lists of frequently eaten foods and then take a trip to the local supermarket to research their origin by analyzing food displays or speaking with the grocer.

What are the consequences of eating grapes from Chile or corn from Mexico? Are there economic or health advantages to eating locally grown fruits and vegetables? Should grocers provide origin information for the produce they sell? These are just a few of the issues students can explore in this lesson. There's also ample opportunity to extend the lesson through action, by visiting a local farmers' market and talking with growers or starting their own vegetable garden at school.

Topic: Food Sources Teaching Level: Grades 4-6 Source: California School Garden Network

In this thirty-minute lesson for very young students, a simple bowl of goldfish crackers helps make concrete the concept of scarcity of resources. In the first part of the lesson, the bowl is passed around the room and students are allowed to take as many crackers as they'd like. In the second, each student receives an equal number of crackers.

The two scenarios serve as an excellent entrée into a discussion of uneven distribution of resources, as students discuss how it felt to get more (or fewer) fish than their classmates. The next step is to expand the discussion to resources in students' homes or in their community that everyone must share.

Topic: Scarcity of Resources Grade Level: P-2 Source: Population Connection

Trip Tally: Discovering Environmental Solutions

What impact does car transportation have on the local environment? That's the key question this lesson aims to ask and answer as students conduct a simple air pollution experiment and analyze the findings in the context of their own weekly trip tally, which documents their comings and goings about town by car, foot, bike, and public transportation.

Students analyze their own travel data, as well as that of the whole class, and then explore strategies for reducing air pollution by choosing to ride their bike rather than drive, or by taking fewer trips.

Topic: Air Pollution Teaching Level: Grades 3-6 Source: Northeast Sustainable Energy Association

Elementary and Middle School

Environmental explorers.

This lesson calls upon observation and analysis skills as students explore and then discuss the changes that have been made to the natural environment. Students observe and document natural and human features in their locale (during a walk around the neighborhood or a trip downtown, for example), and evaluate the impact of changes made by humans, such as the leveling of an area for a subdivision or the damming of a local stream or river.

As a culminating activity, students discuss local environmental and planning issues and then write letters to the local newspapers expressing their views and encouraging specific action.

Focus: Environmental Awareness Teaching Level: Grades 3-8 Source: National Geographic Society

Credit: iStock

The Trash We Pass

A day's worth of classroom garbage becomes the basis for this lesson, which explores the amount of waste students (and their schools, families, and community) produce each day, and the impact of all this trash on the environment. Faced with the dirty truth about how much trash they accumulate, students are asked to brainstorm how to reduce their waste production (by using less, recycling more, and so on) and then to put their newfound knowledge to further use by taking action in their community.

The lesson includes ideas for extending their work beyond the classroom, pursuing activities such as researching local recycling options and advocating with city officials for improvements, or starting a compost pile at school or at home.

Topics: Consumption, Waste Production Teaching Level: Grades 4-7 Source: Redefining Progress

We Are What We Drink

The writings of a Peace Corps volunteer from the Togolese Republic in Africa provide a developing-world context for the exploration of water consumption, water pollution, and the health of individuals and communities. Students explore their own water consumption (the amount of water used in everyday activities; the types of water -- filtered, bottled, and so on) they drink -- and compare this data with the experiences of residents in the Togolese Republic, where clean water is scarce and cholera is endemic.

Topics: Water Quality, Public Health Teaching Level: Grades 3-8 Source: Peace Corps, Coverdell World Wise Schools

Middle and High School

Fishing for the future.

Through a simulation, students model several consecutive seasons of a fishery and explore how such variables as advances in technology, population growth, and attention to sustainable fishing practices impact fish catch and fisheries management. Over multiple "seasons," students confront the economic and environmental impact of overfishing. As the fish population is depleted in one area, for example, they must seek out sources elsewhere or explore more sustainable practices.

This engaging lesson includes thought-provoking writing and discussion prompts, and opportunities for students to extend what they've learned to their own community by exploring the status of commonly owned resources in their town or state.

Topic: Sustainability Teaching Level: Grades 6-12 Source: Facing the Future: People and the Planet

How Big Is Your Footprint?

Using Web tools, students calculate their ecological footprints (the amount of natural resources they consume in a given year) and then, as a group, determine the footprint of the entire class. After creating graphs and finding the mean, the median, the mode, and the standard deviation for the class, students explore a range of discussion questions about reducing their footprint, their responsibility to subsequent generations, the impact of their consumption, and more.

Armed with this new knowledge and awareness, students are prompted to consider the size of their family's footprint, or that of the entire school. What steps might they each take to decrease their footprint? By taking the test again six months later, students will be able to assess the impact of their choices.

Topic: Consumption, Pollution Teaching Level: Grades 8-12 Source: Alliance to Save Energy

High School

Building on the concept of a watershed, students use a field trip to a local body of water (a stream at a local park, for example) to conduct a detailed assessment of the water and surrounding land and then document their findings by mapping and profiling the water and the neighboring area.

This hands-on science lesson teaches students how to take standardized measurements of water characteristics, integrates writing activities as students describe the characteristics of the local watershed, and provides an excellent introduction to issues of water quality. There's also information about using data from, and sharing data with, the worldwide science and education program Global Learning and Observation to Benefit the Environment (GLOBE).

Topic: Water Quality Teaching Level: Grades 9-12 Source: Center for Environmental Education Online

Whose Resource Is It?

Environmental justice is the focus of this lesson, which integrates world history, geography, and government topics into a case study and a role-playing exercise. Students explore the impact of a plan to locate a new industry in a low-income neighborhood, then take on the roles of community members, business executives, and city officials as they advocate for and against building a power plant in a low-income minority neighborhood. Together, they assess the economic, environmental, and social consequences of their decisions.

Through these activities and supplemental readings, students gain a deeper understanding of the ways socioeconomic status impacts the number and types of businesses in a neighborhood -- and the impact these businesses have on residents' health and well-being.

Focus: Environmental Justice Teaching Level: Grades 9-12 Source: Education for a Sustainable Development

Roberta Furger is a contributing writer for Edutopia .

Related green articles:.

• Teach Green : Lesson plans on recycling. Read More
• Truth and Consequences : Teaching global warming doesn't have to spell doom . Read More

Air Pollution - Air around us - Science, Class 6 Video Lecture

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Air Pollution Control

Introduction.

Every day, we take 23,000 breaths. I'm at home. I'm at work. You're in your automobile. On your way to work. That's quite a few breaths.

Breathing is something that most of us don't think about because it isn't something we can see. It's difficult to tell what's in the air around you when you can't see pollutants like invisible gases or particles.

Most people are unaware that according to the World Health Organization, more than 90% of the world's population breathes polluted air. Everyone is affected by this frightening figure, notably youngsters, the elderly, and asthmatics.

If you take a look at the causes of air pollution, you will realize that humans are primarily responsible for air pollution. The growing industrialization has positive and negative impacts on mankind and the environment . Also, the increasing rate of environmental pollution is one of the significant drawbacks that we are facing, resulting from our deeds. Before talking about the control of air pollution, we will have to understand their meaning.

Air Pollution Definition

Air pollution means contamination of air, water, or soil by any substance that is harmful to live organisms. It’s like an introduction or release of a toxic substance into the environment, that can harm the elements in the environment. The pollution can take place because of natural (such as volcanic eruption), and man-made reasons. But nowadays, it’s man-made reasons that are causing more pollution than natural ones. From the increasing number of vehicles to ever-growing industrial wastages in the form of air or water, each contributes to air pollution in some way.

What is Air Pollution?

The air pollution definition says that when any physical, chemical, or biological change takes place in the air and contaminates it, then it is called air pollution. The contamination of air can be caused due to many factors such as poisonous or harmful gases, smoke, fog, smog, dust, etc. air pollution affects both plants as well as animals.

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Types of Air Pollutants

The air pollutants are divided into primary and secondary pollutants. Pollutants are those substances that cause air pollution.

Primary Pollutants:

The primary pollutants responsible for air pollution are the ones that directly cause air pollution. These include harmful gases such as sulfur dioxide coming from the factories. Primary pollutants are those that are produced as a direct result of the process. Sulfur dioxide, generated by factories, is a classic example of a primary pollutant.

Secondary Pollutants:

The secondary pollutants are formed by the process of intermixing or intermingling of primary pollutants. Smog, which is a combination of fog and smoke, is a secondary pollutant.

Causes of Air Pollution:

To prevent the pollution of air around, you have to understand the causes of air pollution at first. The main causes are – 

Burning of Fossil Fuels:

Fossil fuel emits harmful gases such as sulfur dioxide and carbon monoxide into the air. One of the biggest causes of air pollution is sulfur dioxide, which is emitted through the combustion of fossil fuels such as coal, petroleum for energy in power plants, and other industry combustibles.

Automobiles: 

The emission of harmful gases is caused by the excessive use of automobiles.

Agricultural Activities: 

Various processes take place during agricultural activities such as the emission of ammonia, overuse of insecticides, pesticides, and fertilizers . Ammonia is a typical byproduct of agriculture and one of the most dangerous gases in the atmosphere. Insecticides, pesticides, and fertilizers have all become increasingly common in agricultural practices. They release hazardous chemicals into the atmosphere and can pollute water.

Farmers also set fire to the fields and old crops to clear them up for the new cycle of sowing. According to reports, burning to clean up fields pollutes the air by emitting toxic pollutants. 

Factories and Industries:

Emission of harmful gases and chemicals into the air by the increasing industrial activities. Manufacturing companies emit a significant amount of carbon monoxide, hydrocarbons, organic compounds, and chemicals into the air, lowering air quality.

Manufacturing industries may be found in every corner of the globe, and no region has escaped their influence. Petroleum refineries also emit hydrocarbons and a variety of other pollutants, which damage the air and soil.

Mining Activities:

Increasing emission of harmful substances through mining activities.  Mining is the extraction of minerals from under the earth's surface utilizing heavy machinery. Dust and chemicals are released into the air throughout the process, resulting in significant air pollution.

This is one of the factors contributing to the deteriorating health of workers and inhabitants in the area.

Domestic Resources:

Effects of domestic sources such as the use of chemical paints and overuse of air conditioners. Household cleaning products and painting supplies release hazardous chemicals into the air, polluting the environment. Have you ever observed that when you paint your house's walls, it emits a noxious odor that makes it nearly impossible to breathe?

Another source of pollution is suspended particle matter, sometimes known as SPM. SPM refers to the particles that float in the air and is typically caused by dust, combustion, and other factors.

Diseases caused by air pollution:

Air Pollution can lead to increasing diseases like throat infections and lung cancer in humans. Every year, diseases related to air pollution kill and hospitalize millions of people. According to World Health Organization estimates, one out of every eight fatalities worldwide is caused by conditions related to air pollution. New research has found significant correlations between the development of respiratory and cardiovascular disorders and both outdoor and indoor air pollution. Ischemic heart disease, stroke, chronic obstructive pulmonary disease (COPD), lung cancer, and acute lower respiratory infections in children are among the most prevalent diseases induced by air pollution.

"Ischemic heart disease, or coronary heart disease," adds Kevin Wood, Vice President Sales & Marketing at Camfil USA, "is connected to the deposition of calcium or other materials like fat within the coronary artery." "This causes blockages, preventing blood from reaching the heart and other vital organs." According to new research, air pollution hastens the occlusion of arteries, increasing the risk of ischemic heart disease."

Effects of Air Pollution:

The air pollution information shows that increasing air pollution can have an adverse effect on plants, animals, and humans.

Global warming

Air Pollution can increase the amount of global warming as the temperature of the earth will keep rising with the emission of harmful gases. With rising global temperatures, rising sea levels, melting ice from colder places and icebergs, relocation, and habitat loss, an imminent crisis has already been signaled if preservation and normalization measures are not done soon.

Acid rain 

When water droplets combine with harmful chemicals and pollutants, it will lead to acid rain. When fossil fuels are burned, harmful chemicals such as nitrogen oxides and sulfur oxides are emitted into the environment. When it rains, the water droplets interact with the contaminants in the air, becoming acidic and falling to the earth as acid rain. Acid rain has the potential to harm humans, animals, and agriculture.

Ozone layer Depletion

All this will eventually lead to depletion of the ozone layer that protects us from harmful UV sun rays. The presence of chlorofluorocarbons and hydrochlorofluorocarbons in the atmosphere is degrading the ozone layer on Earth.

As the ozone layer thins, damaging rays are emitted back to Earth, potentially causing skin and eye problems. UV rays have the power to harm crops as well.

Thus, we have to work on the prevention of air pollution.

Effects on Animals

Increasing air pollution affects animals and aquatic life, leading them to stray and wander for food. Many of the animals are on the verge of extinction because of this. Animals, sometimes known as wildlife, are particularly vulnerable to the effects of air pollution. Acid rain, heavy metals, persistent organic pollutants (POPs), and other harmful compounds are all pollution concerns.

Insects, worms, clams, fish, birds, and mammals all have diverse ways of interacting with their surroundings. As a result, each animal's exposure to and vulnerability to the effects of air pollution is unique.

Air pollution has two major effects on wildlife.

It has an impact on the area or habitat in which they reside, as well as the food supply's availability and quality.

It is not easy to control air pollution, but it will require some simple steps like:

Avoid Using Vehicles

Prefer using public transport as it will reduce the emission of CO into the air. The availability of carpools can help in the reduction of vehicles which in turn reduces pollution. Prefer walking or cycling to nearby places and many such.

Energy Conservation

Use energy-efficient electrical devices at the workplace and home place. You can keep your lights switched off when not in use. The electrical appliances should be checked on a regular notice period so that it won’t affect the conservation.

Use of Clean Energy Resources

It will help to reduce the pollution level. Instead of using fossil fuels, we can use natural resources to produce energy like Solar Energy, Wind Energy, etc.

By decreasing and eliminating the usage of fire and fire-related items.

Because industrial emissions are one of the leading causes of air pollution, the pollutants can be reduced by controlling or treating them at the source. If a given raw material's reactions produce a pollutant, for example, the raw materials can be replaced with less harmful materials.

Another method of reducing pollution is to use different fuels. CNG – Compressed Natural Gas–powered vehicles are replacing petrol and diesel vehicles in many parts of India. Vehicles that aren't fully equipped with optimal emission engines are the most likely to use these.

Although India has a number of practices aimed at improving air quality, most of them have been forgotten or are not well implemented. There are still many automobiles on the road that haven't had their emissions tested.

FAQs on Air Pollution Control

1. What are the Types of Air Pollution?

There are 4 major harmful types of air pollution – carbon monoxide, sulfur dioxide, nitrogen oxides, and particulate matters and lead pollution

2. How Can the Use of Air Conditioners Cause Air Pollution?

The air conditioners release a gas called CFC (chlorofluorocarbon) which increases air pollution and adversely affects the ozone layer as well.

3. How Many People Can Die from Air Pollution?

According to the statistics provided by WHO, around 7 million people die every year just because of the various effects of air pollution.

4. What is the Air Quality Index?

The air quality index is measured by and used by the official pollution control authorities to show to the public how polluted the air currently is. It’s a measure that shows how polluted the air that we breathe in.

5. What are the Measures for the Control of Air Pollution?

Various methods can be undertaken to control air pollution – we can start by reducing the use of private cars, buying the electric appliances that have an energy star label, conserving energy whenever possible, and making less use of air conditioners.

6. How Can We Succeed in the Prevention of Air Pollution?

Prevention of air pollution will be a difficult task, but not an impossible one.  Apart from the individual efforts, the government authorities and the pollution control authorities should issue strict guidelines for it. Also, a good alternative should be provided for fuels and other industrial pollutants.

Biology • Class 12

• NCERT Solutions
• NCERT Class 6
• NCERT Class 6 Science
• Chapter 15: Air Around Us

NCERT Solutions for Class 6 Science Chapter 15 Air Around Us

Ncert solutions class 6 science chapter 15 – free pdf download.

NCERT Solutions for Class 6 Science Chapter 15 Air Around Us benefits the students in understanding the concepts thoroughly. These NCERT Solutions are prepared by subject-matter experts at BYJU’S as per the 2022-23 CBSE syllabus. This chapter gives knowledge on air, constituents of air, wind, air present in soil and its importance, oxygen and its importance for living organisms, atmosphere and its importance and the importance of plants for our survival.

The questions with their detailed answers will help students to comprehend the concepts and ideas covered in this chapter. Hence, to score good marks in the examinations, students are advised to study NCERT Solutions for Class 6 Science .  These NCERT Solutions are really helpful in getting a better understanding of the concepts of air. Moreover, these solutions will help them prepare well and attempt the annual exam confidently. 

• Chapter 1 Food: Where Does It Come From?
• Chapter 2 Components of Food
• Chapter 3 Fibre to Fabric
• Chapter 4 Sorting Materials into Groups
• Chapter 5 Separation of Substances
• Chapter 6 Changes Around Us
• Chapter 7 Getting to Know Plants
• Chapter 8 Body Movements
• Chapter 9 The Living Organisms and Their Surroundings
• Chapter 10 Motion and Measurement of Distances
• Chapter 11 Light, Shadows and Reflection
• Chapter 12 Electricity and Circuits
• Chapter 13 Fun with Magnets
• Chapter 14 Water
• Chapter 15 Air Around Us
• Chapter 16 Garbage In, Garbage Out

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Access Answers to NCERT Solutions for Class 6 Science Chapter 15 Air Around Us

Exercise Questions

1. What is the composition of air?

Air comprises water vapour, oxygen, nitrogen, carbon dioxide, dust and smoke.

2. Which gas in the atmosphere is essential for respiration?

Oxygen in the atmosphere is essential for respiration.

3. How will you prove that air supports burning?

Place two candles of the same length on a table. Light both candles. Cover one of the candles with an inverted glass tumbler. We can observe that the candle covered with the glass tumbler got extinguished after some time, whereas the other candle continued burning. The candle gets extinguished because the air component inside of the glass tumbler, which supports burning, is limited. Most of the component is used up by the burning candle. However, the other candle is getting a continuous supply of air. This component of air, which supports burning, is known as oxygen.

4. How will you show that air is dissolved in water?

Take some water in a container. Heat it slowly on a tripod stand. Before the water begins to boil, look at the inner surface of the container. We observe tiny bubbles inside. 

These bubbles come from the air dissolved in water. When you heat the water, to begin with, the air dissolved in it escapes. This experiment concludes that air is present in the water.

5. Why does a lump of cotton wool shrink in water?

The lump of cotton wool shrink in water because the air inside the cotton lumps is replaced by water which makes the layer stick together.

6. The layer of air around the earth is known as ___________.

The layer of air around the earth is known as the atmosphere .

7. The component of air used by green plants to make their food is ___________.

The component of air used by green plants to make their food is carbon dioxide .

8. List five activities that are possible due to the presence of air.

The five activities that are possible due to air are as follows:

• Photosynthesis
• Cloud formation
• Respiration
• Transpiration

9. How do plants and animals help each other in the exchange of gases in the atmosphere?

During the process of respiration, animals and plants consume oxygen from the air and release carbon dioxide gas into the air. Besides, green plants also release oxygen gas by utilising carbon dioxide during the process of photosynthesis. Hence, in this way, plants and animals help each other in the exchange of gases in the atmosphere.

Topics Covered in NCERT Solutions for Class 6 Science Chapter 15 Air Around Us

• Is air present everywhere around us?
• What is air made up of?
• How does oxygen become available to animals and plants living in water and soil?
• How is the oxygen in the atmosphere replaced?

To score good marks in the examination, students should solve the previous year question papers and sample papers. This will significantly help them understand the difficulty level of the questions and the marking scheme. Keep visiting BYJU’S, for the latest CBSE updates and notifications. Also, download BYJU’S – The Learning App for an effective learning experience.

Frequently Asked Questions on NCERT Solutions for Class 6 Science Chapter 15

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