The Allegheny County Health Department is considering a proposal to limit idling by diesel-powered vehicles in an effort to reduce harmful diesel fumes.

Diesel exhaust contains toxic chemicals and soot that has been linked to cancer and can cause or worsen asthma attacks.

The county health board agreed yesterday to open a 30-day public comment period and hold a public hearing on the proposed regulation before its next meeting March 2.

The regulation is similar to one enacted by Allegheny County Council last year limiting school bus idling to five minutes. Violators would be issued a warning for a first offense, and be subject to a $100 fine for a second offense and a $500 penalty for subsequent offenses.

Guillermo Cole, health department spokesman, said the hearing date and 30-day comment period have not been set but would be announced soon.

The proposal would affect commercial trucks, buses, construction vehicles, locomotives and marine vehicles.