The Most Hazardous Contaminated Places and Where They Are

Methodology

24/7 Tempo reviewed the 23 Superfund sites determined to be the most hazardous, based on the site’s assigned Hazardous Ranking System (HRS) score determined by the Environmental Protection Agency. Any score higher than 28.5 is deemed a serious enough hazard by the EPA to merit Superfund spending. 

The EPA determines the HRS of a site based on three main categories of risk: The likelihood that a site is releasing — or has the potential to release — hazardous substances into the environment; the toxicity of the waste and how much of it there is; and the proximity of the waste to people. It is important to note that these sites are being cleaned, and some have had their contaminants removed since the HRS assessment grade listed was made.