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. Related stories: 3 major cities declared pollution-stricken Norway boasts world's largest CO2 lab OECD's global environment outlook grim "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. (Photo: Ofer Amram) 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. 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 US 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 US 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. Follow Ynetnews on Facebook and Twitter