Air Pollution in US Cities Quiz
Smog, industrial pollution (10 questions).
Air Pollution in US Cities Quiz: Quick Study Notes
Air pollution remains a significant environmental health risk in the United States. While the Clean Air Act has improved conditions since the 1970s, factors like vehicle emissions, industrial activity, and geography (such as valleys trapping smog) continue to challenge air quality in major metropolitan areas.
Ground-level ozone (smog) forms from sunlight and emissions, while particulate matter (PM2.5) consists of tiny inhalable particles.
A meteorological phenomenon where a layer of warm air traps cold, stagnant, and polluted air near the surface, common in winter.
Landmark 1970 legislation that authorized the EPA to establish National Ambient Air Quality Standards (NAAQS).
Cities in basins or valleys (e.g., LA, Salt Lake City) often suffer worse air quality because mountains block air circulation.
Key Takeaways
- Los Angeles is historically synonymous with photochemical smog due to cars and sunlight.
- Donora, PA, experienced a deadly smog event in 1948 that spurred regulation.
- Vehicle emissions are the leading cause of ground-level ozone in US cities.
- Thermal inversions trap pollution in valley cities like Salt Lake City.
- The EPA sets limits on six “criteria” air pollutants, including lead and sulfur dioxide.
- Wildfire smoke is an increasing source of PM2.5 pollution for East Coast and Western cities.
Frequently Asked Questions
What is the difference between smog and fog?
Fog is a cloud of water droplets near the ground. Smog (smoke + fog) is a type of intense air pollution involving emissions reacting with sunlight or accumulating in stagnant air.
Which US city historically has the worst ozone pollution?
According to the American Lung Association, the Los Angeles-Long Beach region consistently ranks highest for ozone pollution due to traffic density and sunny weather.
What causes thermal inversions?
Thermal inversions occur when a layer of warm air sits on top of a layer of cold air near the ground. This “lid” prevents pollutants from rising and dispersing.
What are “Criteria Pollutants”?
These are the six pollutants regulated by the EPA under the Clean Air Act: Ground-level Ozone, Particulate Matter, Carbon Monoxide, Lead, Sulfur Dioxide, and Nitrogen Dioxide.
How does geography affect pollution?
Physical features like mountains can block wind flow, trapping pollutants in valleys or basins. Coastal cities may also experience land-sea breezes that recirculate polluted air.
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