1. Air Pollution The build up of harmful substances in the air to unhealthy levels causes air pollution. A pollutant that is put directly into the air by human activity is called a primary pollutant. (ex. Soot from smoke)

2. Primary Pollutants

3. Secondary Pollutants Secondary pollutants form when primary pollutants react with other primary pollutants or with naturally occurring substances such as water vapor. (ex. Ground-level ozone that forms when sunlight and car emissions react with oxygen)

4. Primary pollutants from household products, power plants, and motor vehicles.

5. Motor Vehicle Emissions

6. Industrial Air Pollution

7. Air pollution that hangs over an urban area and reduces visibility is call smog.

8. Temperature inversion occurs when the air above is warmer than the air below and traps pollutants in the cooler air.

9. Acid Precipitation Acid precipitation is precipitation that contains high concentrations of acids. When fossil fuels are burned, they release oxides of sulfur and nitrogen. The oxides combine with water vapor in the atmosphere and form sulfuric acid and nitric acid.

10. pH pH is a measure of how acidic or basic a substance is.

11. Acid precipitation affects soil and plants An increase in the concentration of acid in the soil and water is called acidification. The increased levels of acid affect the ability of plants to take in nutrients. In addition, it clogs the surfaces of plants.

12. Acid in Aquatic Ecosystems Changes in pH can kill fish and other aquatic animals. Acid precipitation causes aluminum to build up in the ecosystem which will accumulate in the gills of fish and suffocate them. Can cause fish and amphibians to produce fewer eggs, eggs that do not hatch, and an increase birth defects of the offspring

13. Acid Precipitation and Humans Causes respiratory problems Decreases available food (fish) Dissolves building materials (important monuments and buildings)