For the past three and a half years, the nonprofit group has conducted a petition drive for a car-free park, and yesterday many of them came here with 100,000-plus signatures they gathered, shouting for a "smog-free" and "particulate matter free" Central Park.

"Central Park is the lung of New York City," said Paul Steely White, Transportation Alternative's executive director. "For three hours in the morning and four hours in the afternoon, the solitude and refuge and, really, the livability of the park is compromised by traffic. These are the prime times for people who want to exercise and for kids who want to recreate there after school."

He cited an American Lung Association report claiming that car pollutants are particularly dangerous when people are exercising because people breathe them in deeper into their lungs and last week's report that said New York's air as the most polluted in the nation. "The air here is so bad that people are at greater risk for cancer, respiratory illnesses and premature death," White said.

Though his nonprofit group would like to see cars prohibited permanently from the park, right now, they are calling only for a summer ban "when traffic is at its low and use of the park at its highest," White said.

Wendy Brawer, who designed a Green Map for the city's renewable energy sources, said other nations have been more active to limit cars in cities.

"We realize the need to be healthier; we recognize the problems with asthma and obesity," Brawer said. "All of us feel the weight of a car-centered society."

Manhattan Borough President Scott Stringer and elected officials who represent neighborhoods encircling the park support the summer ban, and City Councilwoman Gale Brewer, D-Upper West Side, is introducing a resolution for a car-free park.

"What a great opportunity for us now to restore Central Park as a place people can go to get away from the cars and the traffic and the everyday lifestyle," Stringer said. "We're asking the administration and the mayor just to try it."

In response, the Dept. of Transportation and the Parks Dept. issued a joint statement saying the agencies "are currently working with the police dept. to assess the feasibility of the proposal."

Closing the loop

According to 2004 study by Transportation Alternatives and the Regional Plan Association:

• The report estimated that up to 60 percent of the traffic using the loop would disappear.
• If drivers were diverted to parallel streets, the report concluded the impact would be small, with fewer vehicles at key locations such as the Fifth Avenue and Central Park West intersection.