NEW YORK — ANYONE who has ever witnessed New York City's daily gridlock of idling cars or the blasts of black diesel exhaust spewing from thousands of trucks and buses here can appreciate the severity of this city's air-pollution problem. New York ranks third in the nation in urban smog - right behind Los Angeles and Bakersfield, Calif., - according to a recent US Environmental Protection Agency survey.
Traffic exhaust is the prime culprit. Carbon-monoxide levels in the city, though improved in recent years, are still 1.5 times higher than federal standards. The city also exceeds federal health standards for ozone levels.
``Today's cars are a lot cleaner than 10 years ago, but there are more of them and people are driving them more,'' says William Baker, chief of the air programs branch of the regional office of the EPA.
In response to a growing mix of internal and external prods, city officials are taking steps to ease the problem.
Under a broad new program proposed to New York City Mayor David Dinkins last month by a special task force, the city plans by April 1992 to buy or convert 385 vehicles - from pickup trucks to garbage compactors and buses - to run on natural gas, methanol, or electricity. That first phase would cost an extra $3.2 million.
The first target figure represents 25 percent of all non-emergency city vehicles that would normally be replaced in that period. By mid-1997 the city wants alternative-fuel vehicles for 100 percent of its replacements.
The level of carbon-based soot from diesel exhaust in mid-Manhattan is also too high to meet federal health standards. New York has stepped up enforcement of a law that bars any diesel vehicles, including the more than 7,000 buses that flow in and out of the city each day, from idling motors for more than three minutes. The penalty is a $400 fine.
Private efforts to make greater use of alternative fuels are also under way. The most enthusiastic proponent locally is the Brooklyn Union Gas Company, which leases two natural-gas buses to a Brooklyn firm that uses them to carry commuters into the city. Two hundred of the 1,400 sedans and trucks in the utility's own fleet also operate on natural gas. ``They run beautifully and they don't need as much maintenance because the oil doesn't get dirty,'' says Alan Smith, a consultant to the firm and a former vice president.
New amendments to the Clean Air Act calling for tighter limits on tailpipe emissions and cleaner-burning gas are a partial spur to both the private and the municipal action. But the city insists that Congress did not go far enough.
City officials say they are acting in large part on the campaign promise of Mayor Dinkins. He pledged that by the end of his four-year term all replacement vehicles in the city fleet would run on alternative fuels. City officials also point to strong state legislation as a spur. The New York legislature last fall followed California in adopting tougher exhaust emissions standards which must be met by an earlier deadline than those passed by Congress.
`THE city is taking a more-progressive position than the federal government,'' insists Sanford Evans, spokesman for New York City's Department of Environmental Protection. ``The feeling here is that we've got to push ahead and become an example.'' The city wants to convince manufacturers that the demand for alternative fuels exists and persuade private firms to follow the city's lead with their fleets.
That mission of setting an example is also the reason Sheldon Leffler, a New York City councilman from Queens, drafted a bill that calls for a three-year conversion to alternative fuels in city replacement vehicles, including 1,200 city buses. The bill, which has been in the works for some months and would provide money for the job, also requires private companies owning 15 or more vehicles to take similar steps. Three natural-gas service stations would be built. The bill is similar to the new plan embraced by the city and is expected to pass the City Council within the next few weeks. ``If the city creates a market for nonpolluting vehicles, other cities will follow,'' insists Mr. Leffler.
``It's a very important little bill that would accelerate this whole process,'' says Eric Goldstein, a lawyer and air pollution expert with the Natural Resources Defense Council.