In what is believed to be the largest asthma study ever undertaken, a team of New York City doctors has found that the main culprits for asthma-related visits to the city’s emergency room are soot, smog and auto emissions — problems they say require greater government clean-air regulation.

The study, which examined the case files of 6 million emergency room patients at 11 municipal hospitals between 1989 and 1995, also found that cold temperatures were a major contributor to attacks. But the authors concluded that man-made environmental conditions–especially pollution-spiked ozone levels during warm-weather months–contributed greatly to the acute breathing difficulties suffered by poor patients who visit city-owned hospitals.

In all, asthma attacks accounted for 6.8 percent of all emergency room visits, a total of nearly 420,000 over the years studied.

“We were surprised by what we found,” says Dr. Richard Sinert, an ER physician at Kings County Hospital. “People had thought that allergies were very important in the incidence of asthma in New York City. We found that pollution was a much more significant factor.”

The paper, which Sinert says will be published in the Journal of the American Medical Association later this year, calls for a tougher air quality laws and stronger enforcement of the federal Clean Air Act. Other recent studies have shown that particulate pollution-especially emissions from the city’s fleet of diesel buses and coal-burning boilers at city schools-contribute to asthma rates in the city’s poorest neighborhoods.

“This report should be a wake-up call for all the officials in New York State who have dragged their feet on air quality,” says Peter Iwanowicz, a lobbyist with Environmental Advocates, an Albany-based anti-pollution group. “For years, everyone’s known that we needed to do something about it. Maybe now some positive change will happen.”

New York City has long been in non-compliance with federal requirements for ozone, particulate and carbon monoxide emissions. In September 1995, the Pataki administration submitted a remediation plan deemed inadequate by environmentalists. Officials from the federal Environmental Protection Agency are still reviewing it.

But in November, EPA head Carol Browner proposed tough new clean air standards for most urban areas. The plan is expected to face tough opposition from congress members who fear the higher standards will cost companies billions of dollars to install anti- pollution devices.

“It’s going to be the number one congressional issue for the first six months of the year,” Iwanowicz predicts.