More likely than not, getting a vehicle from point "A" to point "B" involves combustion of a fossil fuel, a process that emits gasses and affects the environment. In December 1970, the U.S. Department of Transportation reported over 89.9 billion vehicle miles traveled, or VMT. (See Reference 4) That number nearly tripled to over 246.3 trillion VMT in December 2011. (See Reference 3) Such a sharp incline in traffic volume begs the question: how does car pollution affect the environment and the ozone layer? According to the U.S. Environmental Protection Agency, more than half of the air pollution in the nation is caused by mobile sources, primarily automobiles. (See Reference 6) Further contributing to the pollution potential of cars is the fact that they are filled with numerous fluids, which can harm the environment in the cases of leakage or improper disposal.
Vehicle Emissions and Air Quality
When a car’s engine is running, several different types of gasses and particles are emitted that can have detrimental effects on the environment. Of particular concern to the environment are carbon dioxide, a greenhouse gas; hydrocarbons -- any of more than a dozen volatile organic compounds, some of which are known carcinogens; nitrogen oxides; sulfur oxides; and particulate matter, tiny particles of solids, such as metal and soot. Other emissions that affect human health and create smog include ozone and carbon monoxide. (See Reference 1) The good news is that despite the increase of vehicles on the road, air quality today is actually better than it was in the 1970s, thanks to the 1970 Clean Air Act. In fact, lead emissions from cars have been almost completely eradicated because of the phasing out of leaded gasoline. (See Reference 2, page 2)
Effects on the Environment
Vehicle emissions can affect the environment in several ways. Cars emit greenhouse gasses, such as carbon dioxide, which contribute to global warming. (See Reference 2, page 13) Some air pollutants and particulate matter from cars can be deposited on soil and surface waters where they enter the food chain; these substances can affect the reproductive, respiratory, immune and neurological systems of animals. (See Reference 5) Nitrogen oxides and sulfur oxides are major contributors to acid rain, which changes the pH of waterways and soils and can harm the organisms that rely on these resources. (See Reference 9)
Effects on the Ozone Layer
The ozone layer helps to protect life on earth from the sun’s ultraviolet rays, but human activities have contributed to the accelerated depletion of this protective shield. (See Reference 7) Substances that contribute to ozone depletion usually have high concentrations of chlorine or bromine atoms and include chlorofluorocarbons, or CFCs, halons, methyl bromide, carbon tetrachloride and methyl chloroform. Vehicle emissions contain few chlorine- or bromine-heavy substances, and therefore have little effect on ozone depletion. Even though they are not good for human health, hydrocarbons are recognized by the EPA as having no ozone depletion potential. (See Reference 8)
Vehicles contain many different fluids, including motor oil, antifreeze, gasoline, air-conditioning refrigerants, and brake, transmission, hydraulic and windshield-wiper fluids. In most cases, these fluids are toxic to humans and animals, and can pollute waterways if they leak from a vehicle or are disposed of incorrectly. Many vehicle fluids are exposed to heat and oxygen while an engine is running, and undergo chemical changes. These fluids also pick up heavy metals from engine wear and tear, making them even more toxic to the environment. (See Reference 10) Most vehicles manufactured before 1994 use CFC-12 as a coolant; CFC-12 is no longer produced in the U.S. because of its detrimental effect on the ozone layer. Alternative refrigerants are available, but some still have an impact on the ozone layer if they escape your car’s air-conditioning system. (See Reference 8)
- Yale National Initiative: The Effect of Vehicular Emissions on Human Health
- DOT: Transportation Air Quality Facts and Figures January 2006
- DOT: Travel Trends (December 2011)
- DOT: Historical Monthly VMT Report
- EPA: About Air Toxics
- EPA: Sources of Pollutants in the Ambient Air -- Mobile Sources
- EPA: Ozone Science -- The Facts Behind the Phaseout
- EPA: Ozone Layer Protection Glossary
- EPA: What is Acid Rain?
- EPA: Common Wastes & Materials -- Used Oil and Antifreeze
Jennifer King has written and edited since 1994, and now works as a business technical writer. Her articles appear on GardenGuides, eHow and LIVESTRONG.COM. King has a Bachelor of Arts in English, a minor in Latin American and Caribbean studies, coursework in yoga and certifications in nutrition and childhood development.
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