(NEXSTAR) – More than 1,100 sites around the country are suspected of being so contaminated, hazardous or polluted – or are at risk of becoming so polluted – that they have been deemed a national cleanup priority.

The Environmental Protection Agency (EPA) identifies places around the country that pose a risk to people’s health because they have been contaminated by hazardous waste.

Since 1980, the agency has taken charge of cleaning up those sites under a law with the nickname “Superfund.” (Its full name is The Comprehensive Environmental Response, Compensation, and Liability Act, or CERCLA.)

Superfund sites include poorly managed landfills, mining areas or industrial facilities.

As of Sept. 7, when the National Priorities List was last updated, there were 1,178 sites, plus an additional 39 sites that were proposed as new additions. “It is a list of the worst hazardous waste sites identified by Superfund,” the EPA explains.

Ohio is home to 37 Superfund sites, while Pennsylvania alone has 90.

As part of its effort to inform the public about potential threats and hazards in their area, the EPA maps out every site on an interactive map. Zooming in on the map (below) allows you to see more information about the Superfund sites in your neighborhood, city or state.

Clicking on a site’s name gives you more information on why a site ended up on the National Priorities List. For example, clicking around Youngstown shows several problem areas on the Ohio-Pennsylvania border.

There’s the Westinghouse Electric Transformer Plant near Sharon, Pennsylvania, which between 1936 and 1976 leaked harmful chemicals into the groundwater and Shenango River.

Not far from there, is the location of the Sharon Steel Plant. It opened in 1900 and was ordered to stop operations in 1992. But by then, extensive damage had been done. “Throughout its operating history, waste and byproducts of the manufacturing process were transported on rail cars across the Shenango River and discarded down embankments. Waste and byproducts were also piled into large mounds in several areas on the site until 1992,” the EPA writes.

On the Ohio side of the border, near Salem, is another Superfund site at a former Nease Chemical plant. In the ’60s and ’70s, the plant manufactured cleaning products, fire retardants and pesticides – including mirex, an insecticide that was later banned. But while it was still open, some of those chemicals contaminated soil and ran off into Middle Fork of Little Beaver Creek.

There’s also a former coal strip mine near Deerfield Township, where waste stored underground and in open pits contaminated the surrounding area.

Take a closer look at Superfund sites in your area on the map below:

Clicking on a site opens a pop-up window with more information, including the site’s Hazard Ranking System score. That score represents how likely a site is to release harmful substances into the surrounding environment, how toxic the waste on site is, and how many people are (or could be) impacted by the pollution, among other factors. The highest possible score is 100.

You can also view a full list of sites and explore the map on the EPA’s website.

Once a site is put on the National Priorities List, the EPA investigates the dangers posed to human health and pursues the best way of cleaning up the problem. The EPA may force the person or company responsible for the pollution to finance the cleanup, or it may take charge of cleanup if no party can be found responsible.

Once a site is fully cleaned up and the EPA determines there’s no further risk to people’s health or the surrounding environment, it can be deleted from the list. The site can then be redeveloped into something new.