Air pollution has long been linked to a number of health problems, including respiratory and heart diseases.  Now, it has been shown to cause cancer.

The International Agency for Research on Cancer, a division of the World Health Organization, released a report on Thursday which concludes prolonged exposure to air pollution and particulate matter can cause lung cancer and increase the risk of bladder cancer.  Unlike some other environmental carcinogens, air pollution is nearly impossible to avoid, as we all need to breathe. Caused by vehicle exhaust, power generation, industrial emissions, and residential heating, its sources are ubiquitous.

While the report did not quantify risk by country, some places are more polluted than others. Here in the United States, the Clean Air Act has helped improve air quality in recent years. Nonetheless, pollution continues to cause health problems for many people across the country.

Globally, according to the IARC, air pollution contributed to 3.2 million pre-mature deaths in 2010 alone.  More than 200,000 of those were from lung cancer.