Denver's new antismog program works well enough to try again

Would you leave your car home one day a week if it meant breathable air? Denver-area residents were asked to do just that to combat some of the worst air pollution in the country.

The first part of the only voluntary program in the United States to reduce air pollution -- called the Better Air Campaign -- was not a resounding success, but local officials say it showed promise for bringing Denver into compliance with the air standards of the US Environmental Protection Agency (EPA).

Results of the first stage, during the just-ended 1984-85 pollution season here, are being studied by the EPA as well as by state and city officials elsewhere as a possible strategy in battling the stubborn urban problem of dirty air.

The specific goal here is to reduce carbon-monoxide levels. Denver-area drivers were asked to leave their cars at home on a day of the week corresponding with the last number on their license plates. On days when air pollution was especially high, they were asked to curtail all unnecessary trips.

The campaign's goal for the season just past was a 5 percent traffic reduction. Goals for the next two seasons are 10 and 15 percent reductions. This first time out, metro-area drivers cut traffic back by only 3 percent, according to preliminary estimates.

``I would call it a moderate success,'' says James Lents, division director of pollution control at the state Department of Health. ``The big question is, what can we achieve in future years? Present projections are that we will exceed [EPA] standards by about 12 percent in 1987. If we can get just half of that, then it's still worthwhile.''

Denver faces a somewhat unusual pollution problem in that its really dirty air is produced for a short period in the winter. For most of the year, the city's carbon-monoxide level falls below the federally allowable level of nine parts per million (nine parts of carbon monoxide for every million parts of air.)

But for roughly two months, as fall ends and winters settles in, Denver CO levels soar to more than double what the EPA calls legal. From Nov. 15, 1984, to Jan. 15, 1985, carbon monoxide levels hit 19 parts per million.

``That eight-week period is the only time when we have excessively high levels of carbon monoxide,'' says Ann Grady of the health department. But it's enough to put Denver smack at the top of the worst-air-in-the-US list for carbon monoxide.

Denver drivers at present put in 24 million miles a day around the city and will add another 8 million miles to the figure by 1987.

Other cities have different air pollution problems. Los Angeles's infamous ``smog,'' for example, consists of a pollutant called ozone, a sun-fused combination of hydrocarbons and carbon monoxide.

Denver has still another, insidiously visible air pollution blight, known locally as the ``brown cloud.'' It consists of particulate emissions, largely from fireplaces and diesel vehicles.

The US Clean Air Act requires cities that failed to meet air standards by 1982 to do so by 1987. Denver and 44 other cities missed the 1982 mark. To meet the 1987 extension, those cities rely largely on emission equipment installed on new cars. In Denver's case, that equipment has reduced carbon monoxide emissions from 2,600 tons a day in 1978 to 1,600 tons a day now.

A required annual maintenance check knocks another 300 tons a day off the count, and Colorado officials hope the Better Air Campaign will plug another 150 tons, bringing the city in line with EPA standards. If not, EPA may impose its own program.

Dr. Lents wants to try the same basic program again next season, but with some new wrinkles. ``We want to do more with employers, trying to set up flexible hours for employees, giving subsidies to car pools. . . . We want to concentrate on the people who are willing to make changes,'' he says.