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Air Pollution

Introduces air pollution, acid rain, and ozone depletion as issues affecting the atmosphere.

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Air Pollution

Why is the atmosphere important?

Well, it contains all of the air that we breathe. The atmosphere also has other roles and functions, so when we interfere with the atmosphere, we interfere with some important biological processes. And this can have consequences.

The Atmosphere

The atmosphere plays an important part in maintaining Earth’s freshwater supply. It is part of the water cycle. It refills lakes and rivers with precipitation. The atmosphere also provides organisms with gases needed for life. It contains oxygen for cellular respiration and carbon dioxide for photosynthesis.

Air Pollution

Earth’s atmosphere is vast. However, it has been seriously polluted by human activities. Air pollution consists of chemical substances and particles released into the atmosphere, mainly by human actions. The major cause of outdoor air pollution is the burning of fossil fuels. Power plants, motor vehicles, and home furnaces all burn fossil fuels and contribute to the problem (see Table below). Ranching and using chemicals such as fertilizers also cause air pollution. Erosion of soil in farm fields and construction sites adds dust particles to the air as well. Fumes from building materials, furniture, carpets, and paint add toxic chemicals to indoor air.

Pollutant Example/Major Source Problem
Sulfur oxides (SOx) Coal-fired power plants Acid Rain
Nitrogen oxides (NOx) Motor vehicle exhaust Acid Rain
Carbon monoxide (CO) Motor vehicle exhaust Poisoning
Carbon dioxide (CO2) All fossil fuel burning Global Warming
Particulate matter (smoke, dust) Wood and coal burning Respiratory disease, Global Dimming
Mercury Coal-fired power plants, medical waste Neurotoxicity
Smog Coal burning Respiratory problems; eye irritation
Ground-level ozone Motor vehicle exhaust Respiratory problems; eye irritation

In humans, air pollution causes respiratory and cardiovascular problems. In fact, more people die each year from air pollution than automobile accidents. Air pollution also affects ecosystems worldwide by causing acid rain, ozone depletion, and global warming. Ways to reduce air pollution from fossil fuels include switching to nonpolluting energy sources (such as solar energy) and using less energy. What are some ways you could use less energy?

Acid Rain

All life relies on a relatively narrow range of pH, or acidity. That’s because protein structure and function are very sensitive to pH. Air pollution can cause precipitation to become acidic. Nitrogen and sulfur oxides, mainly from motor vehicle exhaust and coal burning, create acids when they combine with water in the air. The acids lower the pH of precipitation, forming acid rain. If acid rain falls on the ground, it may damage soil and soil organisms. If it falls on plants, it may kill them (see Figure below). If it falls into lakes, it lowers the pH of the water and kills aquatic organisms.

Effects of Acid Rain. These trees in a European forest were killed by acid rain.

Ozone Depletion

There are two types of ozone. You can think of them as bad ozone and good ozone. Both are affected by air pollution.

  • Bad ozone forms near the ground when sunlight reacts with pollutants in the air. Ground-level ozone is harmful to the respiratory systems of humans and other animals.
  • Good ozone forms in a thin layer high up in the atmosphere, between 15 and 35 kilometers above Earth’s surface. This ozone layer shields Earth from most of the sun’s harmful UV radiation. It plays an important role in preventing mutations in the DNA of organisms.

Unfortunately, the layer of good ozone is being destroyed by air pollution. The chief culprits are chlorine and bromine gases. They are released in aerosol sprays, coolants, and other products. Loss of ozone has created an ozone hole over Antarctica. Ozone depletion results in higher levels of UV radiation reaching Earth. In humans, this increases skin cancers and eye cataracts. It also disturbs the nitrogen cycle, kills plankton, and disrupts ocean food webs. The total loss of the ozone layer would be devastating to most life. Its rate of loss has slowed with restrictions on pollutants, but it is still at risk.

Health Hazards of Air Pollution

The World Health Organization (WHO) reports that 2.4 million people die each year from causes directly related to air pollution . This includes both outdoor and indoor air pollution. Worldwide, there are more deaths linked to air pollution each year than to car accidents. Research by the WHO also shows that the worst air quality is in countries with high poverty and population rates, such as Egypt, Sudan, Mongolia, and Indonesia.

Respiratory system disorders are directly related to air pollution. These disorders have severe effects on human health, some leading to death directly related to air pollution. Air pollution related respiratory disorders include asthma, bronchitis, and emphysema. Asthma is a respiratory disorder characterized by wheezing, coughing, and a feeling of constriction in the chest. Bronchitis is inflammation of the membrane lining of the bronchial tubes of the lungs. Emphysema is a deadly lung disease characterized by abnormal enlargement of air spaces in the lungs and destruction of the lung tissue. Additional lung and heart diseases are also related to air pollution, as are respiratory allergies.

Air pollution can also indirectly cause other health issues and even deaths. Air pollutants can cause an increase in cancer including lung cancer, eye problems, and other conditions. For example, using certain chemicals on farms, such as the insecticide DDT (dichlorodiphenyltrichloroethane) and toxic PCBs (polychlorinated biphenyl), can cause cancer. Indoors, pollutants such as radon or asbestos can also increase your cancer risk. Lastly, air pollution can lead to heart disease, including heart attack and stroke.

Air Pollution in Cities

Certain respiratory conditions can be made worse in people who live closer to or in large cites. Some studies have shown that people in urban areas suffer lower levels of lung function and more chronic bronchitis and emphysema. If you live in a city, you have seen smog . It is a low-hanging, fog-like cloud that seems to never leave the city. Smog is caused by coal burning and by ozone produced by motor vehicle exhaust. Smog can cause eye irritation and respiratory problems.

Protecting Yourself from Air Pollution

After reading about the effects of air pollution, both indoors and outdoors, you may wonder how you can avoid it. As for outdoor air pollution, if you hear in the news that the outdoor air quality is particularly bad, then it might make sense to wear a mask outdoors or to stay indoors. Because you have more control over your indoor air quality than the outdoor air quality, there are some simple steps you can take indoors to make sure the air quality is less polluted. These include:

  1. Make sure that vents and chimneys are working properly, and never burn charcoal indoors.
  2. Place carbon monoxide detectors in the home.
  3. Keep your home as clean as possible from pet dander, dust, dust mites, and mold.
  4. Make sure air conditioning systems are working properly.

Are there any other ways you can think of to protect yourself from air pollution.


Use the resource below to answer the questions that follow.

  1. How has air quality improved in Southern California since the 1960s? What was a common occurrence for people living in Southern California in the 1960s?
  2. Is the air quality that people currently experience in Southern California healthy? Explain your thinking completely remembering the individual variation which exists in humans.
  3. Why do young and old people seem to be more affected by air quality? Consider what is happening metabolically within people and exposure lengths. Is it safe to assume that since someone seems unaffected, they are in fact not affected?
  4. What is believed to be the primary source of cancer caused from air pollution? Where does this substance come from?


  • Air pollution consists of chemical substances and particles released into the air, mainly by human actions.
  • The major cause of outdoor air pollution is the burning of fossil fuels.
  • Indoor air can also be polluted.
  • Air pollution causes acid rain, ozone depletion, and global warming.
  • Air-pollution can directly cause deaths due to illnesses like asthma and emphysema or indirectly cause deaths by increasing your risk of cancer.
  • There are steps you can take to decrease your exposure to indoor air pollution, such as having carbon monoxide detectors in your home and keeping your home as clean as possible from pet dander, dust, dust mites, and mold.

Practice I


1.What is the major cause of air pollution?

    a. List two specific causes of air pollution.

2. What are two effects of acid rain?

3. What countries are associated with the worst air quality rates?

4. What two factors may be contributing to the poor air quality of these countries?

5. What human system is directly effected by air pollution?

     a. Describe the 3 specific types of health problems.

6. List threee health problems caused indirectly by air pollution.

7. Describe two ways that you can protect yourself from air pollution.

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