Air pollution is primarily caused by human activity. Fossil fuel emissions and industry are the main culprits. A Worldwatch State of the World Report states that air pollution costs the U.S. up to $40 billion annually. In addition to the economic losses, air pollution causes irreparable harm to the environment and its plants and wildlife. The statistics are sobering as are the effects both short term and long term.
The effects of air pollution on humans is well documented. A report by Cornell University estimates that 40 percent of human deaths worldwide are due to pollution. Specifically, air pollution is primary caused by automobiles and industry. Automobile emissions are estimated to be responsible for 60 percent of air pollution in most American cities. The effects of air pollution, however, reach well beyond the cities where the sources of pollution are concentrated.
When contaminants combine with moisture in the air, the result is acidic precipitation, also called acid rain. Acid rain can contaminate or kill plants, which in turn may be ingested by wildlife. It can also have more dangerous and long term effects. Acid rain leaching into soils can alter the pH levels, making life unsustainable. Likewise, changes in acidity in water resources can cause fish kill. In the U.S., over 46 percent of lakes are unable to support life.
Direct evidence of animal deaths was documented following an air pollution event in Donora, Pennsylvania in 1948, when severe smog was caused by a mixture of industrial pollutants and weather conditions. Dogs were found to be most susceptible to the effects of air pollution, with over 15 percent of local pets dying after the incident. Pet deaths have also been documented in Japan, where the average lifespan of dogs is reported as seven to eight years versus the average lifespan of U.S. pets at over 10 years or more.
Air pollution affects wildlife in other ways. Tropospheric ozone near the Earth's surface can damage to lung tissue in wildlife, making them more susceptible to disease. Tropospheric ozone is a secondary ozone layer produced from chemical emissions and pollutants, combined with sunlight. As the protective stratospheric ozone layer degrades due to pollution, an increase in ultraviolet radiation can increase wildlife deaths due to cancer.
Air pollution causes imbalance in the cycle of life. It affects plant life by weakening or killing plant species. In turn, the wildlife that depends upon these species is impacted by dwindling food resources. According to ScienceDaily.com, bird species are becoming extinct at a rate 100 times faster than normal. Dramatic declines in amphibian species since the 1980s have also been reported. Global warming due to pollution was cited as one of the primary causes. Through each link of an ecosystem's food chain, the effects become more dire. Unless air pollution can be controlled, life on the planet is threatened.