The BP oil spill brought attention to one of the worst environmental disasters of the year, and while a cap has contained it so far, the Gulf of Mexico will undoubtedly take years to clean up.

With the world population soaring to nearly seven billion, it's becoming more difficult to find areas that have not been polluted by human development, including right in our own back yard. A recent study published in the National Academy of Sciences shows that the Alberta tar sands are releasing hazardous levels of heavy metals such as lead and mercury into the province's air and water. Of course, the BP oil spill and Alberta tar sands are just a couple more things to throw into the growing list of the world's polluted places.

According to a report on nuclear waste from the Worldwatch Institute, a Washington-based global environmental organization, Lake Karachay in Russia is the most polluted spot on the planet. Originally a weapons production site turned dumping ground for radioactive waste, the legacy of the Cold War weapons program has left the region pock-marked.

The radiation level there is so high it's enough to give a human a lethal dose after one hour of exposure .

The Natural Resources Defense Council has said Karachay is equal to dumping all of the waste tanks at Washington's Hanford Reservation into a 30-acre lake.

The lake has been drying out since the 1960s, allowing radioactive dust to be blown away and irradiating half a million people nearby. To counter this, authorities have filled the lake with concrete to prevent the sediments from shifting, but it's still unknown whether clean up of the contaminated area is possible.

Predictably, the radiation has leaked into the region's ground water supply, and some experts even fear the radioactivity could reach the Tetscha river and then onward to the Atlantic Ocean, which would mean a worldwide contamination.

Claiming the crown for the world's most air-polluted city is Linfen, China. Located in the Shanxi province, Linfen sits in the heart of China's coal belt. The hills in the surrounding area are lined with mines, injecting burning coal, soot and toxic ash into the blue-black hazy air.

According to a Time article, hanging laundry in the city turns black before it dries completely. Dubbed "Hell on Earth" by a British journalist, spending a day in the city is equivalent to smoking three packs of cigarettes.

Around 30 million people rely on the Citarum River as a water source in Bandung, Indonesia, yet industrial waste from textile factories spew into the world's most polluted river daily. Often the only filtration system available for the village of Sukamaju is a towel or sock over a waterspout. Drinking water is boiled, which kills bacteria but it won't get rid of the chemicals and heavy metals.

Aside from factories dumping its waste into the river, locals use it as an open sewer system. Full of garbage and fecal matter, children play and bathe in the black water, and crops are grown beside the "sick" river.

In North America, the City of Angels nabs the title of U.S. city with the most polluted ozone according to the American Lung Association .

L.A., the second most populous city in the U.S. boasts a lethal combination of heavy traffic, sunshine and scorching heat, which all contribute to 18,000 premature deaths a year from particle pollution.

Named the most chemically polluted city in the world by The Guinness Book of World Records , Dzerzhinsk in Russia, has been a toxic dumping ground for decades.

Between 1930 and 1998, estimates of 300,000 tons of chemical waste were improperly disposed in the area. The impact has been huge, and in 2003, Dzerzhinsk's death rate exceeded its birth rate by 260 per cent .

Efforts are being made to clean up these "sick" areas but the battle is still uphill, often with environmental concerns clashing with business interests.

Are we headed towards a future of living in a toxic waste dump?

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