AIR POLLUTION Composition of Air: Mixture composed of 78% Nitrogen (N2), 21% Oxygen (O2), 0.06% Carbon Dioxide (CO2) Also contains water vapor, gaseous pollutants, and solid particles (particulates) Air Pollution – a change to the atmosphere that has harmful effects Types of Air Pollution Smog Acid Rain Global Warming Destruction of the Ozone Layer Indoor Air Pollution

AIR POLLUTION Smog – combination of smoke and fog Photochemical Smog – thick, brownish haze when certain gases in the air react with sunlight Gases mainly come from cars and trucks Gases form ozone – a toxic gas Temperature Inversion – a layer of warm air prevents the pollution (smog) from rising above the city Problems include: Itchy, watery eyes Scratchy throat Lung problems Harms the body’s defense against illness

AIR POLLUTION Acid Rain - a condition that arises when certain gases in the atmosphere react with rain water, turning it acidic Nitrous and Sulfer Oxides + water  nitric acid and sulfuric acid Gas pollutants come from car engines (nitrous oxide) and coal burning plants (sulfer oxides) Lowers pH of rain water below its normal value pH – a scale that measures the acidity of solutions Acid – below 7; Neutral – 7; Base – above 7 (14 is highest) Unpolluted rain water is 5.2 (slightly acidic)  acid rain is when the pH falls well below that level Damages environment Can kill large areas of forests Releases heavy metals out of the soil Makes waterways unsuitable for aquatic life Can destroy certain materials in buildings and statues

AIR POLLUTION Ozone Depletion – harmful pollutants reacting with a layer of our atmosphere known as the ozone layer, causing it to decrease Ozone Layer – a layer of the atmosphere that contains a small amount of ozone (O3) gas About 30 km above surface Helps protect against ultraviolet radiation from sun  UV rays cause sunburn and skin cancer Ozone absorbs UV energy; keeps it from getting to surface Ozone is recycled (see Figure 6, P. 145) Chlorofluorocarbons (CFC’s) – molecules that react with ozone, stopping it from being recycled Come from air conditioners, refrigerators, fire extinguishers, aerosol cans Now CFC’s are banned in most countries Large hole over Antarctica and Australia

AIR POLLUTION Global Warming – the idea that certain pollutants in the atmosphere are causing the temperature of the Earth to rise too quickly Greenhouse effect – certain compounds trap the heat entering the Earth’s atmosphere; prevents it from reflecting back into space Greenhouse gas – gases that cause the greenhouse effect Carbon dioxide is most common greenhouse gas Works like a car window on a hot summer day  heat can get in, just can’t get back out Natural and needed  the Earth’s temperature would be way too cold without this effect Some scientist worry that too many greenhouse gases are accumulating in our atmosphere Carbon dioxide is on the increase Burning of fossil fuels Deforestation Other greenhouse gases include water vapor, methane, and certain nitrogen and sulfur compounds Potential Consequences Dramatic changes in climate Coastal flooding – melting of polar ice caps Mass extinction – weather changing faster than organisms can adapt NOT ALL SCIENTISTS AGREE THAT GLOBAL WARMING IS HAPPENING!

AIR POLLUTION Indoor Air Pollution Allergens such as pollen, dander, dust Cigarette smoke Asbestos – used to be used as an insulator Associated with lung disease Carcinogenic – linked to causing cancer Has to be removed now in public buildings Carbon Monoxide – CO Description: Colorless odorless gas Problem: Binds with blood cells that carry oxygen – keeps oxygen from getting to body cells Source: when wood, coal, oil or gas are not burned completely Can by detectors to warn if levels get too high Radon Description: colorless, odorless gas that is radioactive Problem: can cause lung problems and cancers Source: formed naturally by rocks underground; leaks in through cracks in basements Can install ventilation units to keep Radon from building up

AIR POLLUTION Solutions: Emissions control CFC substitutes Emissions – solid particles and gas that are released into the air Laws set up to limit what factories can put into the air Scrubber – using water to clean emissions before releasing into atmosphere Catalytic converter – a device in cars and trucks that reduces emissions of carbon monoxide, hydrocarbons, nitrogen oxides Forms less harmful carbon dioxide and water CFC substitutes General Conservation Practices Reduse, reuse, recycle Carpool, find alternative ways for transportation Use less energy Support agencies and organizations that are for protecting the environment