Philadelphia, Bakersfield, California and Fresno are America’s most toxic cities based on a recent study that analyzed the quality of water and air in metropolitan places.

Morgan Brennan, the person who conducted the study, said Philadelphia has more than 50 Superfund sites with poor quality of water and large quantity of toxic releases.

Baton Rouge located in Louisiana and New York City completed the top five most toxic metropolitan areas in United States.

The list was compiled by American publishing company website, forbes.com. It went through 80 chief metropolitan areas in the country and analyzed the quantity of Superfund locations. These are unused areas that contain harmful materials.

It also examined the local Air Quality Index, as well as the Toxics Release Index, which is a measurement of how much dangerous material is released, managed or recycled by local industries.

The metropolitan area of Philadelphia comprises more than 50 Superfund sites. Also, California cities have especially poor quality of air. Bakersfield made 43 days to pass AQI to 100 through a 500-point scale in 2009. Zero is the best possible score in the scale.

Fresno received 29 days to pass AQI to 100 while Los Angeles got 14 days. However, majority of the cities in U.S. can go a whole year without getting the AQI pass to 100.

On the list, Los Angeles got the number 6 spot.

However, Brennan informed that the increased levels of toxicity do not essentially mean it has high health risks for local residents. He also said that several cities on the list have already taken steps to lessen the harmful effects of increased levels of toxicity.