Their Smoke, Our Smog: Meet These Midwestern Power Plants

Just under 90,000 people live in Indiana County, Penn., home of the Homer City Generating Station. They, experts say, are the ones who are most directly affected by the thousands of tons of pollutants that the coal-fired plant's three generation units release into the air each year.

But the effects of the plant, and facilities like it, are not limited to Indiana County or the Midwestern locales where many of the country's other biggest coal plants operate. They are on display in New York City, too—like on July 23, when the state Department of Environmental Conservation (DEC) warned residents they would be better off staying indoors because of high ozone levels. A similar warning was issued in the city for the day before and the day before that, and for four other days in July alone.

Ground-level ozone, a primary component of smog, is formed through a series of complex chemical reactions involving heat, sunlight and chemicals including nitrogen oxides. The latter, known as NOx, are a byproduct of combustion—like the burning of fossil fuels. Along with sulfur dioxide, a contributor to acid rain, and particulate matter, more commonly known as soot, the chemicals can travel hundreds of miles downwind—from Homer City, in other words, to the New York metro area's millions of residents just 330 miles away.

The DEC, in fact, lists out-of-state emissions sources as a primary cause of ground-level ozone and one of the Northeast's most serious air pollution problems—along with local automobile exhaust. The scale of the problem is wide; there are hundreds of coal plants in the country, and Michael Seilback, a spokesman for the American Lung Association, says local air can be influenced by facilities worldwide, as far away as China. Still, some plants are bigger than others, some more directly upwind, and some, critically, employ pollution controls that others do not.

Coal is still the most popular energy source in the United States, accounting for about 45 percent of net power production. Mayor Bloomberg, who has called for that number to shrink, this month donated $50 million from his philanthropic fund to the Sierra Club's anti-coal efforts. Still, with public skepticism over nuclear power and the technical hurdles that alternate energy sources face, coal is here to stay for a while – and the plants, sometimes decades old, that generate power from it.

Below, a look at a few of the Midwestern power plants that affect New York, using newly released EPA data on emissions of hazardous air pollutants in 2010, and state-level data on NOx and sulfur dioxide from 2009 – the most current numbers available. As an analysis, it is necessarily incomplete—it does not, for example, include emissions of mercury, which finds its way from distant smokestacks into the local waters and fish, or carbon dioxide, a major coal-plant emission that contributes to global warming. Nor does it focus on smaller, closer facilities that are made more dangerous to New York by their proximity to the city. Even so, it is a list of power plants New Yorkers can remember the next time health officials say not to go outside.

Homer City Generating Station

Homer City, an 1,884-megawatt plant with a chimney nearly as tall as the Empire State Building (it is the tallest in the country), has become something of a poster child for coal-plant emissions.