Air Pollution Anti-Lecture Targets: Describe the sources of air pollution and the effects of different pollutants in the air. Explain how environmental changes can increase or decrease air pollution in an area.

What is air pollution? What causes what we see?

Major Classes of Pollutants found in Ambient Air Carbon oxides Sulfur oxides Nitrogen oxides VOCs SPM Radioactive substances HAPs

Major Outdoor Air Pollutants - EPA CO2 NO2 SO2 SPM Ozone Lead

Primary and Secondary Pollutants Primary: emitted during into troposphere in a potentially harmful form Secondary: formed when primary pollutants react with one another

Stationary vs. Mobile Sources Stationary – power plants and factories Mobile – motor vehicles Remember the electric vehicle FRQ!

Photochemical Smog VOCs + SOx + heat + sunlight (UV radiation)  ground level O3 + other photochemical oxidants + aldehydes + other secondary air pollutants Also known as the red-air smog Occurs in areas with sunny, warm and wet climates

Photochemical Smog - Formation Process starts inside automobile engines and boilers of coal-burning power and industrial plants Due to the high temperatures in there, S and O in the air react to produce sulfur dioxide. In the atmosphere, some of the SO2 converts to SO3 which causes the red haze hanging over cities

Photochemical Smog – Formation con’t Some of the SO2 reacts with hydrocarbons to produce photochemical smog – ozone, nitric acid, aldehydes, PANs, and other secondary pollutants. When days are hotter, there are lower levels of ozone .

Industrial Smog Consists mostly of NO2, aerosols containing nitric acid, and SPMs Also known as brown-air smog due to SPM of salts and soot Found predominately in developed countries with heavy industrialized areas

Industrial Smog - Formation When burned, C in coal and oil is converted to CO2 and CO. Some also ends up as soot. N in coal and oil reacts with oxygen to produce NO2 Ammonium sulfate forms when ammonia reacts with suspended droplets of sulfuric acid

Factors that Reduce Air Pollution Rain and snow Salty sea spray Mountains and hills

Factors that Increase Air Pollution Winds Urban buildings High temperatures Grasshopper effect

What is a temperature inversion and how does it occur?

Temperature Inversions Layer of cool air lies on top of warm air trapping it near the ground. Pollutants concentrate in the stagnant warmer air and can’t disperse

Areas Susceptible to Temperature Inversions Towns and cities located in a valley surrounded by mountains where they experience cold and cloudy weather Mountains and clouds block winter sun Cities with several million people and motor vehicles