By Karen Klinger

Environmentalist and Cambridge resident John Moore is out to change the image of taxicabs as a significant contributor to air pollution.

So far, he's off to a good start.

With Moore's encouragement and the support of Cambridge's Clean Air Cab program and the Whole Foods Market chain, six new hybrid Toyota Camry taxis now are plying the streets of the city. A study suggests that will mean an annual reduction of at least 20 tons of carbon dioxide emissions per cab from the Crown Victoria vehicles the new taxis replace.

It's also good news for the drivers of the hybrid taxis: at $3 for a gallon of gas, they should save up to $21 in fuel costs per shift, during which cabs in the city typically travel about 100 miles.

Moore is an architect and a founder of Boston Clean Air Cabs, which works to create incentives for taxi owners to convert their older cabs to hybrids or alternative fuel vehicles. In Boston, the program has resulted in the conversion of 34 cabs to date, with a goal of turning at least 10 percent of the city's 1,800 taxis "green" by the end of the year.

Last spring, Moore's suggestion that Cambridge get involved in the conversion program got an enthusiastic response from Richard Scali, chairman of the city's license commission, which regulates taxicabs. Moore also met with Lee Kane, an environmental specialist, or "eco czar," at Whole Foods, which agreed to help with underwriting.

As a result, the city provided $10,000 and Whole Foods $5,000 toward the purchase of each of the new hybrid taxis. In return for the food chain's contributions, the cabs will sport Whole Foods logos for three years. Five of the taxis are operated by Ambassador Brattle Cab and the sixth by Classic Cab.

At a news conference in front of city hall, with the spiffy white-and-green hybrid cabs parked nearby, City Councilor Henrietta Davis praised Moore for his work, saying "He's the man." She noted that while many private cars are on the road no more than an hour a day, taxicabs often operate around the clock, so "they have 24 times more impact on greenhouse gas" emissions.

Moore said a study he conducted along with Boston Cab and the Boston Public Health Commission found that in city driving conditions, hybrid cabs got at least 60 percent better mileage than Crown Victoria taxis that were at least three years old.

A report by the Natural Resources Defense Council also says that hybrid vehicles reduce emissions of nitrogen oxides, which are important contributors to ground-level smog, by between 73 percent and 89 percent compared to Crown Victoria models.

Scali said there are 251 licensed taxis operating in Cambridge in addition to the new hybrids, all but nine of them sedans. Cab companies willing to replace their existing vehicles with hybrids will receive $10,000 from the city toward the purchase of each car, with the money coming from the sale of two taxicab medallions.

The most recent medallion was sold for $385,000. Scali said revenue from medallion sales also will be used to fund programs including the Cambridge Taxicab School and the management of accessible taxi vans for the disabled.

Moore predicts that hybrid taxi iniatives will proliferate as the vehicles prove their worth on both an environmental and economic basis. In addition to Boston, Chicago and New York have hybrid cab programs, plus some smaller cities.