A new study in the journal Geophysical Research Letters pins the blame for L.A.'s foul air on our four-stomached friends.
"You might not think of Los Angeles as a cow town. But there are nearly 300,000 cattle in the region, according to the U.S. Department of Agriculture. And now flights to measure local air pollution have revealed that the cows may be a bigger factor in dangerous air pollution than the cars are," writes Biello.
"The good news: it's a lot easier to control emissions from a few big dairy farms than 10 million vehicles. So an effort to reduce the pollution from cows and their bacteria could have a bigger impact on Los Angelenos air than further emission cuts from cars."