Air pollution is killing 3.3 million people a year worldwide, according to a new study that includes this surprise: Farming plays a large role in smog and soot deaths in industrial nations.
Scientists in Germany, Cyprus, Saudi Arabia and Harvard University calculated the most detailed estimates yet of the toll of air pollution, looking at what caused it. The study also projects that if trends don't change, the yearly death total will double to about 6.6 million a year by 2050.
The study, published Wednesday in the journal Nature, used health statistics and computer models. About three quarters of the deaths are from strokes and heart attacks, said lead author Jos Lelieveld at the Max Planck Institute for Chemistry in Germany.
The findings are similar to other less detailed pollution death estimates, outside experts said.