Summary

Air pollution can be thought of as gaseous and particulate contaminants that are present in the earth’s atmosphere. Chemicals discharged into the air that have a direct impact on the environment are called primary pollutants. These primary pollutants sometimes react with other chemicals in the air to produce secondary pollutants. The commonly found air pollutants, known as criteria pollutants, are particle pollution, ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides, and lead. These pollutants can harm health and the environment, and cause property damage. The historical record shows that the climate system varies naturally over a wide range of time scales. In general, climate changes prior to the Industrial Revolution in the 1700s can be explained by natural causes, such as changes in solar energy, volcanic eruptions, and natural changes in greenhouse gas concentrations. Recent climate changes, however, cannot be explained by natural causes alone. Natural causes are very unlikely to explain most observed warming, especially warming since the mid-20th century. Rather, human activities can explain most of that warming.

The primary human activity affecting the amount and rate of climate change is greenhouse gas emissions from the burning of fossil fuels. Greenhouse gas concentrations in the atmosphere will continue to increase unless the billions of tons of our annual emissions decrease substantially. Increased concentrations are expected to increase Earth’s average temperature, influence the patterns and amounts of precipitation, reduce ice and snow cover, as well as permafrost, raise sea level and increase the acidity of the oceans. These changes will impact our food supply, water resources, infrastructure, ecosystems, and even our own health. Acid rain is a term referring to a mixture of wet and dry deposition from the atmosphere containing higher than normal amounts of nitric and sulfuric acids. The precursors of acid rain formation result from both natural sources, such as volcanoes and decaying vegetation, and man-made sources, primarily emissions of sulfur dioxide (SO₂) and nitrogen oxides (NOx) resulting from fossil fuel combustion. Acid rain causes acidification of lakes and streams, contributes to the damage of trees and many sensitive forest soils. In addition, acid rain accelerates the decay of building materials and paints, contributes to the corrosion of metals and damages human health. The ozone depletion process begins when CFCs and other ozone-depleting substances (ODS) are emitted into the atmosphere. Reductions in stratospheric ozone levels lead to higher levels of UVB reaching the Earth’s surface. The sun’s output of UVB does not change; rather, less ozone means less protection, and hence more UVB reaches the Earth. Ozone layer depletion increases the amount of UVB tat lead to negative health and environmental effects.

Review Questions

1. What are the major air pollution sources?
2. What are the causes of sick building syndrome?
3. Why is secondhand smoke dangerous?
4. Why is EPA is concerned about particles that are 10 micrometers in diameter or smaller?
5. What are some possible effects of climate change?
6. What are the major kinds of ozone depleting substances?

Attributions

CK12. (2015). Reducing ozone destruction. Accessed August 31, 2015 at http://www.ck12.org/book/CK-12-Earth-Science-Concepts-For-High-School/section/13.32/. Available under Creative Commons Attribution License 3.0 (CC BY 3.0). Modified from Original.

EPA. (n.d.). Climate change. Accessed August 31, 2015 at http://www.epa.gov/climatechange/. Modified from original.

University of California College Prep. (2012). AP environmental science. Retrieved from http://cnx.org/content/col10548/1.2/. Available under Creative Commons Attribution 4.0 International License. (CC BY 4.0). Modified from original.

Essentials of Environmental Science by Kamala Doršner is licensed under CC BY 4.0. Modified from the original.