CHAPTER 22: AIR POLLUTION

1. CHAPTER 22: AIR POLLUTION

2. Section 22.1 – The Air Pollution Problem • Air is a mixture of gases: • 78% Nitrogen • 21% Oxygen • 1% small amounts of argon, carbon dioxide, and water vapor. • As air moves, it picks up materials formed by: • natural events - sand and dust storms, volcanic eruptions, forest fires, ocean spray, and decaying organisms. • human activities - major source. • Pollutants – harmful materials that enter the environment. • Air pollution – the harmful substances released into the atmosphere.

3. Section 22.1 – The Air Pollution Problem Outdoor Pollutants • Particulates – tiny solids suspended in the atmosphere. • Dangerous because these tiny particles are easily inhaled with air and become trapped in the lungs. • Most common include: ash, dust, and soot. • Others include pollen, liquid droplets in smoke or smog, traces of metal (lead, iron, copper), pesticides and fertilizer dust. • The most gaseous pollutants are oxides. • Oxides – are compounds of oxygen and another element. • Most common elements with oxygen are carbon, sulfur, or nitrogen. • Released when fossil fuels and organic matter are burned.

4. Section 22.1 – The Air Pollution Problem • Outdoor Pollutants • Photochemical smog – a yellow-brown haze formed when sunlight reacts with pollutants produced by cars. • Often develop in cities with heavy automobile traffic. • Ozone is a chemical found in photochemical smog. • Ozone is very corrosive, easily breaks down rubber and some synthetic fibers, and poisonous to plants and animals. • Nitrogen dioxide – also found in photochemical smog. • It is a brown gas and gives the smog its brown coloration.

5. Section 22.1 – The Air Pollution Problem • Outdoor Pollutants • Hydrocarbons are another gaseous pollutant made up of Hydrogen and Carbon. • Methane is the most common; produced by the digestive tract, certain bacteria and decaying organic matter. • Chlorofluorocarbons – CFC’s – compounds of carbon, chlorine, and fluorine. • Once used in refrigerators, air conditioners, aerosol cans, and in the production of polystyrene foam.

6. Section 22.1 – The Air Pollution Problem Indoor Pollutants • Home products such as plastics, insulation, and cleaners give off harmful fumes. • Air circulation is often poor during the winter. • The deadliest of all indoor pollutants is cigarette smoke. • Secondhand smoke from filtered cigarettes contains higher levels of particulates from burning paper and tobacco than the smoke inhaled by the smoker. • Radon gas – colorless, odorless, radioactive gas. • Forms when radium, a radioactive element in soil, breaks down, enters a person’s home through the basement. • Cause of lung cancer.

7. Section 22.1 – The Air Pollution Problem Common Indoor Pollutants

8. Section 22.3 – Global Effects of Air Pollution • There are three major problems threatening the global environment: • 1. Acid precipitation/rain • 2. Ozone depletion • 3. Global warming

9. Section 22.3 – Global Effects of Air Pollution Acid Precipitation • Rain or snow that is more acidic than normal precipitation. • Acidity is measured on a pH scale. • A pH of 7 is neutral • A pH of less than 7 is acidic • A pH of greater than 7 is basic • Acid rain has a pH of about 5.6 • Burning fossil fuels produce oxides. • Acids are formed in the atmosphere when water reacts chemically with the oxides. • Acid precipitation has become more common in the last 200 years because more fossil fuels are being burned!

10. Section 22.3 – Global Effects of Air Pollution Ozone Depletion • At the surface of Earth, ozone is a corrosive, poisonous gas. • The layer of ozone 20 to 50 km above the Earth’s surface is vital to life. • Ozone forms a protective layer around Earth. • The ozone layer absorbs the sun’s UV radiation, preventing it from reaching Earth’s surface. • UV radiation can cause sunburn, blindness, skin cancer and damage to crops.

11. Section 22.3 – Global Effects of Air Pollution • Causes of Ozone Depletion • The main cause of ozone depletion is CFC pollution. • CFC’s are inert; which means they stay around for several thousand years. • The CFC’s rise up to the ozone layer and the UV radiation causes the CFC’s to break down releasing Chlorine and Fluorine atoms which break apart ozone.

12. Section 22.3 – Global Effects of Air Pollution Global Warming • The greenhouse effect – the trapping of radiated heat by gases in the atmosphere. • The Earth’s atmosphere allows light energy to enter, but traps some infrared radiation. • It raises the average global temperature about 350C. • Without the greenhouse effect, life on Earth would probably be impossible. • The most abundantnatural greenhouse gas is carbon dioxide. • Methane, oxides, ozone, CFC’s, and water vapor are also greenhouse gases. • The greenhouse gases are rising because of the pollution caused by human activities (burning fossil fuels).

13. Section 22.3 – Global Effects of Air Pollution • Global warming – an increase in Earth’s average surface temperature caused by an increase in greenhouse gases. • Ice cores can be used to gather samples of the atmosphere as it existed in the past. • It now gives us reliable records of Earth’s atmosphere for the last 200,000 years. • Problems of rising Earth temperatures. • Polar caps will melt. • Ocean will expand. • Sea levels will rise • Land will flood. • Saltwater will enter the groundwater system