A number of California’s big cities were named as one of the “Most Toxic Cities,” according to a recently released list by Forbes.

The Forbes ranking was based on poor air quality, lack of clean water and a high rate of superfund sites make these metros most contaminated.

See the full list of toxic city rankings, by clicking here.

The list was comprised of the country’s 40 largest metropolitan statistical areas; it ranked the number of superfund sites in the city, number of facilities releasing toxic chemicals, pounds of toxic chemicals released in area and air quality ranking.

Los Angeles topped the list as one of America’s most toxic cities.

“Los Angeles is in a geographic basin surrounded by mountains,” says Brian Turnbaugh, policy analyst for the Environmental Right to Know project at OMB Watch, a government watchdog organization, according to Forbes. “The pollution doesn’t go away; it kind of just sits there, creating these horrible smog days.”

Atlanta took honors as the most toxic city.

Earlier this week, PublicCEO reported rankings on the dirtiest air cities done by the American Lung Association. The list ranked Los Angeles as the worst city by ozone pollution in California.