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Vehicular Air Pollution: What Is It and Where Does It Come From?
Motor vehicles play a major role in air pollution. They are the single largest contributor of the precursors of ground-level ozone, which is a major urban pollutant. Motor vehicles also contribute significantly to particulate matter (PM) pollution. Both kinds of pollution stem from burning fossil fuels and vehicle use, and both contribute to cardiovascular and respiratory problems.
Here's the Science
Motor vehicles generate three major pollutants: hydrocarbons, nitrogen oxides and carbon monoxide. Hydrocarbons react with nitrogen oxides in the presence of sunlight (ultraviolet radiation) to form ground-level ozone. Elevated ozone levels mainly occur during the months of May through September. Nitrogen oxides also help form acid rain. Carbon monoxide, a colorless, odorless, deadly gas, can impair mental and visual functions and have other negative effects at high levels of exposure.
Pollutants are released as a result of vehicle use when:
- Fuel is burned in the internal combustion engine and the combustion products are emitted through the tailpipe.
- Heat causes fuel to evaporate from under the hood and throughout the fuel system. Hot, sunny days and engines warmed by running provide heat to vaporize fuel into the air.
- Refueling at service stations, where gasoline vapors escape into the air.
Air Pollution in the Big Apple
New York pizza, high fashion, Broadway shows—these are all things that New York does well. Unfortunately, however, another thing we're doing well is polluting the air. Metro New York has some of the most polluted air in the United States and much of it comes from our cars. The U.S. Environmental Protection Agency (EPA) has rated the New York metro area as not meeting federal guidelines for ground-level ozone and particulate matter pollution.
Ozone Pollution, Ozone Layer—What's the Difference?
Ozone pollution and the ozone layer are two different things. The naturally occurring "ozone layer" in the upper atmosphere is good—it protects life on Earth by filtering out ultraviolet radiation from the sun. Ground-level ozone pollution is bad. Ozone pollution damages lung tissue, worsens respiratory disease and can make people more susceptible to respiratory infections. Adults with existing cardiovascular problems, the elderly and children are especially vulnerable to ozone pollution.1
Short-term exposure to elevated levels of ozone can cause eye, nose and throat irritation, respiratory symptoms and decreases in lung function. The respiratory symptoms can include shortness of breath, chest pain and coughing. Days with high outdoor ozone levels tend to have increased hospitalizations for respiratory conditions and increased daily mortality rates. More limited evidence suggests that short-term exposure to elevated ozone levels also might aggravate heart symptoms in people with pre-existing heart disease or high blood pressure.
Some studies suggest that long-term exposure to elevated ozone levels may be associated with permanent changes in airway structure and reductions in lung function. An increased risk of developing asthma has been found among students who were likely to have experienced long-term elevated ozone exposure because they participated in athletic programs in areas with high average ozone levels.
Particulate Matter Pollution
Clean Air NY is concerned with a kind of particulate matter known as PM2.5 or fine particulate matter. Fine particulate matter is a mix of tiny solids and droplets that are invisible to the human eye. This is because they are 2.5 microns or less in width-2.5 microns is about one-thirtieth the width of a human hair.2
Like ground-level ozone, PM can worsen pre-existing cardiovascular and respiratory conditions. Your efforts to reduce driving will especially help the ill, elderly and children who are most at risk. In particular, we want to help:
- The estimated 1.4 million people with cardiovascular disease in the five boroughs
- The 460,000 adults and 160,000 children with asthma in New York City
Want the Scoop on Today's Air?
The Air-Quality Index (AQI) is a method devised by the EPA for reporting each day's air quality.
To be more specific, the AQI indicates how dirty the air is. The AQI numbers are associated with a color, a level of health concern and what measures people should take to reduce their exposure to pollutants. Several pollutants are measured by the AQI, including ground-level ozone and PM. Pollution levels are measured on a scale of 0 to 500. A 50 is considered good air quality with low risk of health effects. Anything more than 100 is considered unhealthy for sensitive groups, values above 150 are considered unhealthy for everyone and levels of more than 300 are very rare.3 To see today's air quality, visit the Local Air Quality Info section of this site.
Sign up now to become part of Clean Air NY.
1 U.S. Environmental Protection Agency. 2007. Ground-level Ozone: Health and Environment. http://www.epa.gov/air/ozonepollution/health.html (accessed March 16, 2007).
2 New York State Department of Health. 2003. Fine Particles (PM2.5) Questions and Answers. http://www.health.state.ny.us/nysdoh/indoor/pmq_a.htm (accessed March 16, 2007).
3 AIRNow. 2007. Air-Quality Index: A Guide to Air Quality and Your Health.
http://airnow.gov/index.cfm?action=aqibroch.aqi#2 (accessed March 16, 2007). |
