Cars, once again, are killing us. They're killing us in crashes and accidents, yes, and they're encouraging us to grow obese and then killing us a little more slowly. But, more than ever before, they're killing us with their pollution. Particulate air pollution, along with obesity, is now the two fastest-growing causes of death in the world, according to a new study published in the Lancet. The study found that in 2010, 3.2 million people died prematurely from the air pollution – particularly the sooty kind that spews from the exhaust pipes of cars and trucks. And of those untimely deaths, 2.1 million were in Asia, where a boom in car use has choked the streets of India and China's fast-expanding cities with smog.""