Lovely. I was driving down I-95 the other day, and there was a diesel truck spewing such dense, thick smoke from both smokestacks that it looked like fog settled across the eight-lane highway in its wake. I said to my friend, "Wouldn't you think someone would, oh, I don't know, enforce the law? How the hell did that truck ever pass inspection?" (He told me not to ask such silly questions.) Now it's more important than ever to enforce the air pollution laws, in light of this news:

LONDON (AP) — Diesel fumes cause cancer, the World Health Organization's cancer agency declared Tuesday, a ruling it said could make exhaust as important a public health threat as secondhand smoke.
The risk of getting cancer from diesel fumes is small, but since so many people breathe in the fumes in some way, the science panel said raising the status of diesel exhaust to carcinogen from "probable carcinogen" was an important shift.

"It's on the same order of magnitude as passive smoking," said Kurt Straif, director of the IARC department that evaluates cancer risks. "This could be another big push for countries to clean up exhaust from diesel engines."

Since so many people are exposed to exhaust, Straif said there could be many cases of lung cancer connected to the contaminant. He said the fumes affected groups including pedestrians on the street, ship passengers and crew, railroad workers, truck drivers, mechanics, miners and people operating heavy machinery.

Hah! So much for my friends who make fun of me for walking on a treadmill at the gym, instead of outside. Did you know that urban runners take in even more pollution, because they have larger lung capacity?

The new classification followed a weeklong discussion in Lyon, France, by an expert panel organized by the International Agency for Research on Cancer. The panel's decision stands as the ruling for the IARC, the cancer arm of the World Health Organization.

The last time the agency considered the status of diesel exhaust was in 1989, when it was labeled a "probable" carcinogen. Reclassifying diesel exhaust as carcinogenic puts it into the same category as other known hazards such as asbestos, alcohol and ultraviolet radiation.

The U.S. government, however, still classifies diesel exhaust as a likely carcinogen. Experts said new diesel engines spew out fewer fumes but further studies are needed to assess any potential dangers.

"We don't have enough evidence to say these new engines are zero risk, but they are certainly lower risk than before," said Vincent Cogliano of the U.S. Environmental Protection Agency. He added that the agency had not received any requests to reevaluate whether diesel definitely causes cancer but said their assessments tend to be in line with those made by IARC.