1. Air is an important natural resource.
Human Impact on the Atmosphere
Why is the atmosphere important?
Air is an important natural resource.
The air you breathe forms part of Earth’s atmosphere.
The atmosphere is a mixture of gases that surrounds Earth. 1

2. Human Impact on the Atmosphere
The atmosphere provides gases that organisms need to survive, including oxygen and carbon dioxide.
The atmosphere absorbs harmful high-energy radiation coming from space. 2

3. The atmosphere keeps Earth warm.
Human Impact on the Atmosphere
Why is the atmosphere important?
The atmosphere keeps Earth warm.
Without the atmosphere, temperatures on Earth would not be stable.
The greenhouse effect is the way by which certain gases in the atmosphere absorb and reradiate thermal energy. 3

4. Human Impact on the Atmosphere
What is air pollution?
The contamination of the atmosphere by pollutants from human and natural sources is called air pollution.
Air pollution can come from natural sources, such as volcanic eruptions, wildfires, and dust storms.
In cities and suburbs, most air pollution comes from the burning of fossil fuels. 4

5. Human Impact on the Atmosphere
Air pollution can be classified as gases such as carbon monoxide, sulfur dioxide, and ground-level ozone.
Air pollution can also be classified as particulates. Particulates consist of tiny particles of solids that are suspended in air or water.
The particulates from vehicle exhaust are a major cause of pollution in cities. 5

6. Vehicle exhaust is a common source of air pollution in urban areas.
What pollutants can form from vehicle exhaust?
Vehicle exhaust is a common source of air pollution in urban areas.
Ground-level ozone is produced when sunlight reacts with vehicle exhaust and oxygen in the air.
Although ozone in the ozone layer is necessary for life, ground-level ozone is harmful. 6

7. Vehicle exhaust also produces smog.
Human Impact on the Atmosphere
Vehicle exhaust also produces smog.
Smog is a brownish haze that forms when ground-level ozone and vehicle exhaust react in the presence of sunlight. 7

8. Smog can damage the lungs and irritate the eyes and nose.
Human Impact on the Atmosphere
Smog can damage the lungs and irritate the eyes and nose. 8

9. How does pollution from human activities produce acid precipitation?
Precipitation such as rain, sleet, or snow that contains acids from air pollution is called acid precipitation.
Burning fossil fuels releases sulfur dioxide and nitrogen oxides into the air.
When these gases mix with water in the atmosphere, they form sulfuric acid and nitric acid. 9

10. Sulfuric acid and nitric acid are strong acids
Sulfuric acid and nitric acid are strong acids. They can make precipitation so acidic that it is harmful to the environment. 10

11. Human Impact on the Atmosphere
What are some effects of acid precipitation?
Acid precipitation can cause soil and water to become more acidic than normal.
Changes in soil acidity cause soil to lose some of the nutrients that plants need. 11

12. This can harm aquatic organisms.
Human Impact on the Atmosphere
Acid precipitation can also make lakes and streams more acidic and cause soils to release toxic metals into the water.
This can harm aquatic organisms. 12

13. Air quality is the measure of how clean or polluted the air is.
Human Impact on the Atmosphere
What are measures of air quality?
Air quality is the measure of how clean or polluted the air is.
As pollution increases, air quality decreases.
Two major threats to air quality are vehicle exhausts and industrial pollutants. 13

14. The Air Quality Index (AQI) is a number used to describe the air quality of a location.
The higher the AQI number, the more people are likely to have health problems linked to air pollution.
The air inside a building can become more polluted than the air outside. 14

15. What are some sources of indoor air pollution?15

16. How can air quality affect health?
Daily exposure to small amounts of air pollution can cause serious health problems.
Certain people, such as children, elderly people, and people with health problems, are especially vulnerable to the effects air pollution.
Short-term effects include coughing, headaches, and wheezing. Long-term effects include lung cancer and emphysema. 16

17. Average global temperatures have also risen in recent decades.
How might humans be changing Earth’s climates?
As a result of burning fossil fuels, the atmosphere today contains about 37 percent more carbon dioxide than it did in the mid-1700s.
Average global temperatures have also risen in recent decades. 17

18. It is hard to know exactly how much the extra greenhouse gases change the temperatures.
Computer models designed to understand climate change predict that average global temperatures will continue rising. 18

19. Many changes on Earth have already been linked to higher temperatures.
What are some predicted effects of climate change?
Many changes on Earth have already been linked to higher temperatures.
Changes in rainfall patterns and rising sea levels will have many negative effects on life on Earth.
Such changes will likely have political and economic effects on the world. 19

20. How is the ozone layer affected by air pollution?
Earth’s protective ozone layer is thinning over the polar regions, allowing more harmful ultraviolet radiation to reach Earth’s surface.
Chemicals called chlorofluorocarbons (CFCs) cause ozone to break down. CFCs once had many industrial uses, but now they are banned.
However, CFCs released in the atmosphere decades ago will stay there many more decades, breaking down more ozone. 20

21. Humans greatly affect the land, water, and air.
What are conservation and stewardship?
Humans greatly affect the land, water, and air.
If we wish to keep using our resources in the future, we need to conserve and care for them.
Conservation is the wise use of natural resources. By practicing conservation, we can help make sure that resources will be around for future generations.

22. Stewardship is the careful and responsible management of a resource.
Stewardship of Earth’s natural resources will ensure that the environment stays clean enough to help keep people and other living things healthy.
Any action that helps to maintain or improve the environment is an act of stewardship.

23. There are many ways we can reduce air pollution.
How can we reduce air pollution?
There are many ways we can reduce air pollution.
Everybody can help reduce air pollution in many different ways.
Energy conservation is one of the most important ways to reduce air pollution.

24. Fossil fuels are the most commonly used energy resource.
How can we reduce air pollution?
Fossil fuels are the most commonly used energy resource.
When fossil fuels are burned, they release pollution into the air.
If we use less energy, we burn fewer fossil fuels.
There are many ways to conserve energy.

25. There are many ways to generate energy without creating much air pollution.
By developing technology for alternative energy resources, we reduce the amount of pollution created by burning fossil fuels.
For example, compact fluorescent lightbulbs help limit air pollution. They use less energy to make the same amount of light.

26. Governments in many countries work independently and together to reduce air pollution.
Because air isn’t contained by borders, some solutions must be international.
The Kyoto Protocol is a worldwide effort to limit the release of greenhouse gasses—pollution that can warm the atmosphere.