A new study shows that diesel exhaust is the most dangerous cancer-causing toxin in the Los Angeles area reports the Orange County Register.

The findings of the two-year study, released Friday by the South Coast Air Quality Management District, were disputed by the California Trucking Assn. The $750,000 study measured concentrations of 31 different contaminants.
The study includes a cancer-risk map that shows high pollution contamination over the area's freeways. It says that diesel exhaust accounts for 71% of cancer risk from air contaminants in the LA basin.
The study has local officials calling for new, tougher regulations for diesel fleets. A spokesman for the South Coast Air Quality Management District said they would try to expand their ability to regulate diesel emissions. Right now, they are working on a rule that would target school buses, transit buses and garbage trucks in fleets of 15 or more.
The California Trucking Assn. says the study is "sensationalizing."
"All it's going to do is displace the trucking companies and put them out of business," CTA's Stephanie Williams told the paper.
The study will be available at the air district's web site, http://www.aqmd.gov.