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Questions | Answers

1. 78% N2, 21% O2, 0.9% Argon, 0.035% CO2

2. Stationary: sources of air pollution other than transportation (e.g., power plants)
Mobile: air pollution from transportation

3. Primary pollutants enter the air directly as the pollutant
Secondary pollutants are formed in the air through chemical reactions between primary pollutant(s) and one or more air components, often in sunlight (photochemical smog).

4. Acute effects are caused by short duration exposure and/or have immediate effects
Chronic effects are caused by long duration exposure and/or have long term effects.

5. Chemical nature: how active and harmful the pollutant is.
Concentration: amount of pollutant per volume.
Persistence: how long the pollutant stays around before breaking down.

6. The Clean Air Act

Sulfur Dioxide: mostly stationary fuel combustion; acid deposition and direct damage to animals, humans, structures
Particulate Matter: mostly fuel combustion and industry; depends on pollutants, but most affect respiratory system.
Lead: now mostly smelting plants and paints; affects nervous system development
Ozone: mostly fuel combustion; affects eyes, respiratory system, vegetation, structures
Nitrogen Dioxide: mostly fuel combustion; acid deposition, photochemical smog, respiratory system
Carbon Monoxide: mostly mobile fuel combustion (transportation); reduces blood's capacity to carry oxygen (headaches), forms O3.

8. Criteria air pollutants have maximum national ambient air quality standards (NAAQS) -- maximum concentration in air.
Noncriteria air pollutants have emission standards -- maximum that can come out of a smokestack.

9. When the temperature of the air at ground level is cooler than the air just above it, then a temperature inversion occurs.

10. Temperature inversions occur when cool air is created under or slips under relatively warmer air at ground level.

11. Because the cool air just sits on the ground and does not mix, air pollutants become more concentrated in this cooler layer at the ground level where we breathe.