Raleigh among America's cleanest cities

Raleigh has been ranked No. 3 among America's Cleanest Cities. The City of Oaks edged Orlando and Las Vegas, but was just nudged out by McAllen, Texas (No. 1) and Little Rock Arkansas (No. 2).

The Environmental Protection Agency (EPA) defines toxic substances as "chemicals or compounds that may present an unreasonable threat to human health and the environment." In terms of toxicity, the EPA's goal is to "identify and reduce the risks from toxic substances," collecting a plethora of toxicity-related data as it relates to land, water and air.

For our Cleanest and Least Cleanest Cities lists, we started with the 80 largest MSAs for which toxicity data is available. These include namesake cities as well as the counties neighboring them, as defined by the U.S. government's Office of Management and Budget. We then ranked these geographic areas based on five equally weighted measures of pollution and toxicity.

Here are Raleigh's numbers:

No. 3: Raleigh, N.C.
MSA: Raleigh-Cary, N.C.
Air quality rank: 41
Water quality rank: 1
Superfund rank: 24
Pounds of on-site toxic releases (2009): 492,000