Switzerland -- Diesel fumes cause cancer, according to the World Health Organization.
The ruling could make exhaust as important a public health threat as secondhand smoke.
The risk of getting cancer from diesel fumes was tiny, but the panel ruled that since so many people breath in fumes in some way, the status of diesel exhaust was changed from "probable carcinogen" to "carcinogen".
"The number one finding is that diesel exhaust exposures are carcinogenic to humans, a group one carcinogenic, the highest level you can possibly have," said
Christopher Portier, Chairman International Agency for Research on Cancer. "Also associated with diesel exhaust is linkage to bladder cancer, but that's a less, that's a much lower linkage."
A WHO panel discussed the issue for a week in France before the ruling was issued.