The U.S. Environmental Protection Agency classifies parts or all of the seven-county Pittsburgh Metropolitan Statistical Area to be in nonattainment of health-based limits for three major air pollutants it regulates: fine particulates, or PM2.5, ground-level ozone and sulfur dioxide.
Places are designated nonattainment areas for failing to meet air quality standards over a period of three consecutive years. Here’s more about the pollutants that remain a problem in the region:
PM2.5
These particles are 30 times smaller than the diameter of a human hair and can get deep into the lungs, even the blood stream. The biggest sources of PM2.5 are those that burn fossil fuels on a large scale, including power plants, steel and coke works, and mobile sources such as cars, diesel trucks and buses. Smaller sources include wood stoves and restaurant fryers.
Scientific evidence links short- and long-term PM2.5 to reduced lung function, chronic bronchitis and premature death. It also aggravates asthma and lung disease. Even short-term exposure raises the risk of heart attacks and arrhythmias among people with heart disease.
Ground-level ozone
Ground-level ozone is formed in sunlight when hydrocarbons, such as those in car exhaust, interact with nitrogen oxides. Gasoline and diesel vehicles are chief sources. A component of smog, it is most likely to reach unhealthy levels on hot sunny days in urban environments.
Breathing ozone can worsen asthma, bronchitis and emphysema, reduce lung function and inflame the lining of the lungs. Repeated exposure can permanently scar lung tissue. Even relatively low levels of ozone can cause problems. Most at risk are people with lung disease, those who are active outdoors, older adults and children, whose lungs are still developing.
Sulfur dioxide
Sulfur dioxide (SO2) is one of a group of sulfur oxide gases. The highest amounts of SO2 emissions are produced when fossil fuels are burned at power plants and other industrial facilities. These emissions pose their own health risks, but can also react with other compounds in the air to form PM2.5, one of the most dangerous and widespread air pollutants.
Short-term exposure to SO2 has been linked to a range of respiratory problems, including bronchoconstriction and increased asthma symptoms. People with asthma are at greater risk when they are breathing more heavily, such as while exercising.
Most of the seven-county Pittsburgh MSA meets federal SO2 air standards, with the exception being parts of Allegheny and Beaver counties.
This is the second installment in a three-part series. Go here to read the previous or next installments.