HARRISBURG The Pennsylvania Environmental Quality Board has proposed a regulation that would limit the amount of time a diesel-powered commercial motor vehicle can idle to no more than five minutes in a 60-minute period.

However, the rule includes exemptions for passenger loading and unloading.

The emissions-reduction proposal is primarily aimed at long-haul truckers, but it also will impact motorcoaches, school and transit buses, and many delivery trucks.

The regulation must now be opened to public comment and be discussed at public hearings before final consideration by the Environmental Quality Board. Then, it must be approved by the Independent Regulatory Review Commission, which reviews all proposed state regulations and, finally, the state attorney general.

The state Department of Environmental Protection says the regulation - once fully enacted in 2010 - will reduce annual emissions of nitrogen oxide, volatile organic compounds and particulate matter, as well as help reduce carbon dioxide.

Several exemptions are included in the measure, including idling for:

Active loading or unloading of passengers or property

Operating work-related mechanical or electrical operations other than propulsion

Maintenance, repairs and inspections for safety-related purposes

Passenger and school buses may idle for up to 15 minutes during a 60-minute period to provide heating or cooling when non-driver passengers are on board.

Pennsylvania joins other East Coast states, including Delaware, Maryland, New Jersey and New York, in adopting anti-idling measures.

The Environmental Quality Board will accept public comment on the regulation for 60 days following its publication in the Pennsylvania Bulletin. It also will hold three public hearings on the regulation.

For more information, go to www.depweb.state.pa.us, keyword: Diesel Idling.