The World Health Organization's cancer agency has determined that air pollution causes lung cancer.
The International Agency for Research on Cancer (IARC) said that in 2010, air pollution-related lung cancer killed 223,000 people worldwide. More than half those deaths occurred in China and East Asian countries.
More from GlobalPost: How China chokes its neighbors
The IARC said that air pollution also increases the risk of bladder cancer.
Previously, some compounds found in dirty air, like diesel exhaust, were declared to be cancer-causing. This is the first study that points the finger at polluted air in general.
“Classifying outdoor air pollution as carcinogenic to humans is an important step,” IARC Director Dr. Christopher Wild said in a statement. “There are effective ways to reduce air pollution and, given the scale of the exposure affecting people worldwide, this report should send a strong signal to the international community to take action without further delay.”