1. Catalytic Converters http://videos.howstuffworks.com/science-channel/31428-deconstructed- catalytic-converter-video.htm AIR POLLUTION REVIEW…

2. Natural air pollutants: volcanoes, fires, dust storms Plants emit volatile organic compounds Mechanisms in the biosphere remove, assimilate, and recycle natural pollutants Hydroxyl radical (OH): a naturally occurring compound Oxidizes many gaseous pollutants to harmless products brought to land or water by precipitation Sea salts: a cleansing agent that helps form raindrops Picked up by wind flowing over oceans Sunlight: breaks down organic molecules ATMOSPHERIC CLEANSING

3. They also remove anthropogenic pollutants from the air Highly reactive hydrocarbons are rapidly oxidized Nitrogen oxides are oxidized within a day Less reactive substances (e.g., CO) take months Atmospheric levels of hydroxyl are determined by levels of anthropogenic air pollutants Hydroxyl’s cleansing power is used up Pollutants are able to build up Photochemical breakdown of ozone is a major source of hydroxyl radical HYDROXYL RADICALS

4. THE HYDROXYL RADICAL

5. http://www.ecokids.ca/pub/games_activities/water/index.cfm ACIDIFIED LAKE