1. Human Impact on The Atmosphere1

2. The atmosphere absorbs harmful UV radiation coming from space.
The atmosphere provides gases that organisms need to survive, including O2 and CO2.
The atmosphere absorbs harmful UV radiation coming from space. 2

3. 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. 4

5. What is air pollution?
The contamination of the atmosphere by toxins 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. 5

6. Air pollution can be classified as gases such as carbon monoxide (CO), sulfur dioxide (SO2), and ground-level ozone.
Air pollution can also be classified as particulates. These are tiny particles of solids that are suspended in air.
The particulates from vehicle exhaust are a major cause of pollution in cities. 6

7. Pollutants from vehicle exhaust.
Vehicle exhaust is a common source of air pollution (CO, SO2, HC) in urban areas.
Ground-level ozone is produced when sunlight reacts with vehicle exhaust and oxygen in the air. Ground-level ozone is harmful to all living things. 7

8. 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. 8

9. Smog can damage the lungs and irritate the eyes and nose.9

11. Pollution and Acid Precipitation.
Precipitation 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. 11

12. 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. 12

13. Effects of Acid Rain.
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. 13

14. This can harm aquatic organisms.
Acid rain can also make lakes and streams more acidic and cause soils to release toxic metals into the water.
This can harm aquatic organisms. 14

15. Air Quality
Air quality is the measure of how clean or polluted the air is.
As pollution increases, air quality decreases.
Two major threats are vehicle exhausts and industrial pollutants. 15

16. The Air Quality Index (AQI) is a number used to describe the air quality of an area.
The higher the AQI number, the more people are likely to have health problems linked to air pollution. 16

17. How are humans changing the Earth’s climate?
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 have changed temperatures.
Computer models designed to understand climate change predict that average global temperatures will continue to rise. 18

19. Predicted long term effects
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. The Ozone Layer.
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. 20

21. Unfortunately, CFCs released in the atmosphere decades ago will stay there many more decades, breaking down more ozone. 21

22. Reducing 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.

23. Fossil fuels are the most commonly used energy resource
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. What can you do?