What is air pollution and what is its global impact?
Interactive Study Guide
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Guiding Question 21.2
What are the main types and sources of outdoor air pollution? What are the common types of air pollutants regulated by the EPA?
Why You Should Care
Air pollution comes in many forms: gases like carbon monoxide (CO), liquids like sulfur dioxide droplets (SO2), and solids like particulates (PM). Most of these air pollutants are chemically reactive and create or speed reactions with other pollutants to create new types of pollutants (called secondary air pollutants). Also, most of these air pollutants can be produced by either natural or anthropogenic sources. Today, most of the air pollution comes from anthropogenic sources and concentrates in areas with significant agriculture, industry, or transportation.
In the United States, the Environmental Protection Agency (EPA) is the branch of the federal government that regulates air pollution levels. Using laws like the Clean Air Act of 1970 and its later amendments, the EPA monitors levels of criteria air pollutants that affect humans and ecosystems and other pollutants that have long-term effects (like mercury from burning coal).
Test Your Vocabulary
Choose the correct term for each of the following definitions:
Term
Definition
Particles or droplets small enough to remain aloft in the air for long periods of time.
Pollution that enters the air from dispersed or mobile sources.
Hazy air pollution that contains a variety of pollutants including sulfur dioxide, nitrogen oxides, tropospheric ozone, and particulates.
Pollution that enters the air from a readily identifiable source such as a smokestack.
Air pollutants released directly from both mobile sources (such as cars) and stationary sources (such as industrial and power plants).
A secondary pollutant that forms when some of the pollutants released during fossil fuel combustion react with atmospheric oxygen in the presence of sunlight.
Air pollutants formed when primary air pollutants react with one another or with other chemicals in the air.
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1.
Which of the following air pollutants is NOT a primary air pollutant?
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2.
Which of the following human and natural sources produce secondary air pollutants?
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3.
Which of these PM sizes are small enough to affect humans?
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4.
Why do primary and secondary air pollutants not reach the stratosphere?
The prevailing winds can spread the pollutants, but they are mostly produced and react in the troposphere. Few of them make it high enough to reach the stratosphere.
5.
Which of these is NOT a criteria air pollutant (CAP)?
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Which of the following CAPs harm the blood directly?
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Which of the following CAPs affect producers?
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8.
Which of these is NOT released by vehicles burning fossil fuels?
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Thought Question: Most of this table is made up of reactive chemicals that in turn react with other chemicals or living things to damage them. Why is unreactive carbon dioxide (CO2) on this list?
Carbon dioxide may not react to damage humans, animals, or plants, but it is a greenhouse gas that increases the temperature of the lowest part of the atmosphere (the troposphere). The increased levels of CO2 are suspected of causing the increasing global temperatures that scientists call climate change.
