Air pollution can come from many sources. Industry, power plants, cars, and trucks, as well as many consumer products, all contribute to poor air quality. This means that everyone—businesses and consumers—contribute to the problem. Since air currents can carry pollutants great distances, millions of people are impacted by air pollution, making it our region’s largest environmental health risk.
The U.S. Environmental Protection Agency (EPA) monitors and sets national health standards for six common air pollutants (ozone, particulate matter, carbon monoxide, nitrogen oxides, sulfur dioxide, and lead). The Delaware Valley does not meet the standards for two of these pollutants—ground-level ozone and fine particulate matter (PM2.5). The EPA has designated the Greater Philadelphia Region as air quality "nonattainment areas" for these pollutants. Each nonattainment area encompasses different counties in the region.
The Philadelphia - Atlantic-City – Wilmington Ozone Nonattainment Area [0.6 MB pdf] includes 18 counties in New Jersey, Pennsylvania, Delaware, and Maryland.
The Philadelphia – Wilmington PM2.5 Nonattainment Area [0.6 MB pdf] includes eight DVRPC counties and New Castle County, Delaware. Mercer County, New Jersey, is in the New York - Northern New Jersey - Connecticut PM2.5 Nonattainment Area. [0.6 MB pdf]
Because of air pollution chemistry, high levels of ground-level ozone commonly occur during the summer months. High levels of particle pollution can occur at any time of the year, but are most common during the summer months.
Ozone in the upper atmosphere protects us from the sun’s harmful rays. There, ozone plays an important role protecting life on earth (good ozone). At ground level, where people breathe, ozone can be harmful to lungs and the environment. In the summer, sunlight and heat can “bake” pollutants to form ground-level ozone, also known as smog (bad ozone). One way to remember the difference between good and bad ozone is the phrase "Ozone is good up high and bad nearby."
Fine Particle Pollution or PM2.5
Particle pollution is the term for tiny drops of liquid or small bits of dust, metals, or other materials (smaller than 2.5 microns in size) that float in the air. Some particles, such as soot or smoke, are large enough to see. Other particles are so small that they can only be seen with an electron microscope. Particle pollution comes from a variety of natural and manmade sources, such as cars, power plants, and forest fires.