The World’s 10 Worst Cities

Arsenic-laced drinking water, lead-contaminated soils and choking air pollution are sadly just the start in some of the world's dirtiest places

You may already know about the pollution plight of Linfen, China. But how about the heavy metals Pittsburghers breathe in on a daily basis? Or the incomparable smog Milanesi put up with? PopSci has culled an eye-opening selection of some of the world’s most problematic cities. From the painfully high cancer rates in Sumgayit, Azerbaijan to the acid rain destroying La Oroya, Peru, writer Jason Daley will walk you through the lowest of the low; and explain why, despite it all, there’s still hope for these places.

And check out PopSci‘s complete coverage of the future of the environment at

Milan, Italy

Ah, Milan, home to great shoes, high fashion and more pm10s—small pollution particles that can cause cancer and breathing problems—than any other city in Europe. In fact, according to a study by Italian environmental group Legambiente, Milan has more smog than any other city in Europe and the continent’s second-highest level of ozone. Most of the problem comes from the city’s love of driving, but that’s changing quickly: Congestion pricing in downtown Milan implemented in January has dropped traffic by 26 percent and, residents hope, will lead to drops in smog as well.

Norilsk, Russia

According to a study of the world’s most polluted places by environmental think tank the Blacksmith Institute, Norilsk, Russia—home to 134,000 residents and the world’s largest heavy-metal-smelting firm, Norilsk Nickel—makes the top 10. Norilsk’s Soviet-era plant spews tons of heavy metals like nickel and cobalt into the air, leading to severe respiratory and throat diseases in children and a life expectancy 10 years below the Russian average for plant workers. But the company says it’s taking measures to clean things up, investing in technology to sequester heavy-metal dust, and says it plans to move the smelter outside the city limits in the near future.

Pittsburgh, Pennsylvania

Pittsburgh recently wrested the title of America’s most polluted city from Los Angeles—at least when it comes to short-term particle pollution like soot, aerosols, heavy metals and exhaust. But the city of 335,000, which has transitioned from an industrial town to one of the country’s most livable cities, may not be to blame for its bad air. According to some research, much of Pittsburgh’s pollution is blown in from factories and power plants in Ohio.

Mexico City, Mexico

Mexico City is a natural pollution trap. Surrounded by mountains on three sides and located 7,400 feet above sea level, the soot and exhaust from the city’s four million mostly high-polluting cars gets trapped in a cloud over the city, which experiences 300 days a year of exceedingly high ozone levels. To fix things, the city has begun a pilot project retrofitting 25 diesel buses with particulate filters. Now, if it could only retrofit the other 2,975 buses . . .

Dakar, Senegal

Dakar is West Africa’s cosmopolitan hub, but just a stone’s throw from the city is an environmental catastrophe. The Baie de Hanne, which provides drinking and household water to two million people, contains levels of fecal streptococci more than 17 times World Health Organization standards, as well as a stew of heavy metals and tannery waste. The Blacksmith Institute is currently working with the World Bank to implement an international cleanup effort.

Sumgayit, Azerbaijan

Sumgayit used to be the New Jersey of the Soviet Union—the town was the nation’s center of chemical and pesticide production. Today, it is still feeling the aftereffects of years of untreated, mercury-contaminated waste dumped directly into streams feeding the Caspian Sea. Cancer rates in the city of 275,000 are sky-high. The World Bank has stepped into the city, which was declared an environmental disaster area, and is helping to clean up old plant sites.

Linfen, China

This city of more than four million is in the heart of Shanxi, China’s coal-production hub, and has frequently been deemed the most polluted city in the world; citizens suffer from choking clouds of coal dust as well as drinking water polluted with arsenic. But Linfen is not the only city in the country with environmental woes—the World Bank estimates that 16 of the world’s 20 most polluted cities are found in China’s industrial areas.

La Oroya, Peru

For 85 years, the citizens of La Oroya have been smelting lead, copper and zinc. Now 99 percent of the town’s children harbor levels of toxic lead that exceed acceptable limits. Acid rain has destroyed most of the surrounding vegetation, turning the region into a wasteland. So far, the Peruvian government has put the city of 35,000 on a list for environmental remediation, but activists are attempting to pressure the smelter’s owner, the Doe Run company of Missouri, to step in and begin a serious cleanup.

Cubatao Valley, Brazil

The Cubatao Valley, a region home to more than two million people, is Brazil’s industrial and chemical heart. The Cubatao River, the area’s main water source, is clogged with 1.5 million tons of raw sewage per year and more than 10,000 kilograms of toxic industrial waste per month. A study in 1980 showed that over a third of residents had tuberculosis, pneumonia, emphysema and other respiratory diseases. Since 2000, Brazil’s new water agency has made a concerted effort to clean up the Cubatao region, investing some $1.1 billion to improve the Tiete River, another major waterway in the valley.

Kabwe, Zambia

For 92 years, the lead and copper mines outside Kabwe, Zambia, ran with little or no environmental protections. It’s been more than a decade since the smelters shut down, and the lead level found in the average child, who bathes in a lead-contaminated stream and is constantly exposed to contaminated soil, is still five to 10 times the maximum allowed by the U.S. EPA. In many cases, children carry almost fatal levels of contamination. So far, the World Bank has provided $40 million to help relocate some neighborhoods in Kabwe, and several other international and local groups are implementing extensive programs to teach residents about lead poisoning.