Norilsk, Russia

Number of people potentially affected: 134,000
Type of pollutant: Air pollution — particulates, sulfur dioxide, heavy metals, phenols
Source of pollution: Major nickel and metal mining and processing

Norilsk was founded in 1935 as a Siberian slave labor camp, and life there has pretty much gone downhill since. Home to the world's largest heavy metal smelting complex, more than 4 million tons of cadmium, copper, lead, nickel, arsenic, selenium and zinc are released into the air every year. Air samples exceed the maximum allowance for both copper and nickel, and mortality from respiratory diseases is much higher than in Russia as a whole. "Within 30 miles (48 km) of the nickel smelter there's not a single living tree," says Fuller. "It's just a wasteland."

— by Bryan Walsh