1. What Causes Air Pollution?
Unit 2: The Atmosphere

2. Air Pollution What color is the sky?
Air pollution – when harmful substances build up in the air to unhealthy levels
Mostly human-induced, but also natural
Sulfur dioxide
Dust, pollen, spores
Mexico city – most dangerous for children!

3. Primary and Secondary Pollutants
Primary pollutant – put directly into the air by human activity
Examples will be discussed in more detail in our activity
Secondary pollutant – form when
primary pollutants react with each other
or with natural compounds in the air
Example: Ozone
Sources of air pollutants
Household products
Power plants
Motor vehicles
Emissions react with oxygen in the atmosphere

4. History of Air Pollution
Notions of air pollution occurred as early as 2000 YA
1273 – King Edward ordered that the burning of a particular dirty coal was illegal
Made much worse by global industrialization
One man was even hanged!

5. Motor Vehicle Emissions
1/3 of total pollution comes from gasoline burned, most of which is from passenger vehicles!
Clean Air Act (1970) gave the EPA the authority to regulate vehicle emissions
Gradual elimination of lead in gasoline
Catalytic converters clean exhaust before it leaves the vehicle
Zero-Emission Vehicle Program (California, now 10 states)
Encourage the development of zero-emission vehicles (no tailpipe emissions, no emissions from gasoline, no emission control systems which can deteriorate).
Electric cars, but also Hybrids and Fuel Cell Cars

7. Industrial Air Pollution
Many industries—power plants—burn fuel to produce energy
Fossil fuels, which produce sulfur dioxide, nitrogen oxides, and VOCs
Clean Air Act requires many industries to use scrubbers, which actually spray gases with water – how simple!
Smog – when air pollution hangs over urban areas and reduces visibility
Results from chemical reactions that involves the sun, air, exhaust, and ozone
Temperature Inversion – warm air is above the cooler air, trapping pollutants! More likely in a valley (Los Angeles)
Electrostatic precipitators use a charged champers and an induced electrical charge

8. Activity: Primary Air Pollutants
In groups of no more than 3, make a poster on one of the following air pollutants: Carbon monoxide (CO), Nitric oxides (NOx), Sulfur dioxide (SO2), Volatile organic compounds (VOCs), or Particulates (PM)
Your poster must include the following information:
A drawing of the chemical compound
A description of the pollutant
Primary sources of the pollutant
Two effects of the pollutant, at least one of which must be on humans
Use color; write your names on the back of the poster!