March 19, 2014, 6am PDT
Unlike the U.S., most passenger vehicles in Europe run on diesel fuel, not gasoline, and from a public health perspective, diesel emissions can severely exacerbate particle pollution during weather inversions like the one Paris is now experiencing.
December 12, 2011, 10am PST
With pollution levels becoming dangerous in Rome, Italy, the government is taking a hard line on driving. In late November, only cars with even-numbered license plates were allowed to drive in the city, with odd plates the next.