In a city that has trouble getting residents to rat on criminals, officials now want Philadelphians to tattle on a new kind of miscreant: truckers and bus drivers who leave their engines idling, spewing pollutants into the air.

Yesterday, the Clean Air Council unveiled a hotline and Web resource, www.idlefreephilly.org - yes, there's an iPhone app - where sidewalk sleuths can report where, when, and how long idling occurs.

Both city and state regulations prohibit drivers from leaving their engines idling for more than five minutes.

"It's unnecessary," said Eric Cheung, senior attorney with the Clean Air Council. "All it does is create pollution and greenhouse gases."

And health problems. An asthma sufferer himself, Cheung said he often finds himself coughing when he passes an idling truck.

The U.S. Environmental Protection Agency has said diesel exhaust is a likely carcinogen. It can prompt asthma attacks and exacerbate other respiratory diseases; it can lead to increased hospital admissions and emergency-room visits, heart attacks, and premature death.

Nan Feyler, chief of staff of the city Department of Public Health, which oversees air-pollution enforcement, said the agency endorsed the hotline effort. She said Philadelphia is fourth in the nation in the number of deaths attributed to diesel particulates. Citywide in 1999, she said, 727 deaths and 990 heart attacks were attributed to diesel particulates.

Officials, however, said the reports would not lead directly to tickets or other enforcement actions. The idea is to identify city hot spots that can be the focus of educational efforts or targeted enforcement.

Yesterday's announcement came less than a week after an EPA report showed the Delaware Valley still fails to meet air-quality standards for fine particulate matter, which is small enough to go deep into the lungs.

Idling also costs money. A typical diesel engine burns a gallon of fuel every hour that it is idling. Yesterday the fuel was nudging toward $3 a gallon at some locations.

Gerard J. Coyle, a vice president of the Evans Network of Companies, a trucking firm, said yesterday that idling-reduction programs over the last year - including computer programs that automatically turn off untended engines after five minutes - have saved the company 360,000 gallons of diesel.

But with staff and funds at low ebb, enforcement of the laws has been lax. Many drivers simply ignore it.

Although they know that transportation contributes 40 percent of the region's air pollution, officials were unable to quantify how much comes from idling.

But they identified idling as "low-hanging fruit" that could easily be avoided.

At a midday event yesterday, they passed out key-chain tags with the hotline number: 1-877-853-1552. (For now, the recording identifies itself only as "SeeClickFix," but officials promise to change it.)

The Web site has been operating in test mode, and in recent weeks, observers reported buses idling near 30th Street Station, ambulances outside a medical facility in Southwest Philadelphia, and a delivery truck outside an 18th Street drugstore.

Contact staff writer Sandy Bauers at 215-854-5147 or sbauers@phillynews.com.