A Clean Air Act ‘Success Story’: Carbon Monoxide

While government officials, environmentalists and public health advocates were grousing about smog and soot, the Clean Air Act quietly all but won the war against carbon monoxide, according to a prestigious panel of the National Academy of Sciences.

When federal standards were set for carbon monoxide, one of the most dangerous air pollutants, in 1971, 90% of the monitors around the country registered violations.

Today, air monitors in only a few places still show violations. And even in those hot spots, the period when the standard is exceeded has shrunk to only a day or two a year, according to the report released Wednesday by the academy’s National Research Council.

Carbon monoxide “regulation has been one of the greatest success stories in air-pollution control, reducing the problem, once widespread, to a few difficult areas,” the report states.

Controls have greatly diminished carbon monoxide’s negative health effects, such as early deaths for people with heart disease and accidental carbon monoxide poisoning, according to the report.

Regulations requiring auto manufacturers to reduce emissions and forcing refineries to clean up fuels have been key to the success.

“It’s certainly a clean-air success story,” said Donald Zinger, assistant director of the Environmental Protection Agency’s office of transportation and air quality. “The tailpipe standards this country has put in place, in addition to the clean-fuel programs, are a big part of that success.”

Carbon monoxide emissions are expected to decrease even more as older cars without emission controls are retired and replaced by new cars, which will be even cleaner, starting in the 2004 model year, officials said.

But the report said that despite the progress, more attention is needed where carbon monoxide persists -- in communities such as Anchorage, and Lynwood and Calexico, Calif.

In these areas, weather, topography and sometimes geography have conspired to hamper pollution control.

They experience severe atmospheric inversions in the winter, with cooler, polluted air close to the ground, trapped by warm air above.

Calexico, which had the second-highest number of days in violation between 1995 and 2001, is across the border from Mexicali, Mexico, which does not control vehicle emissions. Many vehicles in Mexicali are older and lack emission controls.

Most of the carbon monoxide in Calexico’s air drifts in from across the border, especially in winter when wind speeds are low and the inversions are strongest. The situation is worsened by the fact that Calexico is in a valley.

Fairbanks, Alaska, faces the toughest meteorological challenges, according to the report. Low winter temperatures combine with unusually strong inversions and low wind speeds, greatly limiting the air available to dilute and disperse carbon monoxide and other pollutants. The city is sheltered on three sides by hills.

But during the panel’s study, the city had not one day in violation. That was down from eight days in violation of the carbon monoxide standard in 1995 and well over 100 days a year in the early 1970s.

Lynwood, a community of 64,000 south of downtown Los Angeles, has borne the brunt of the metropolitan area’s carbon monoxide emissions for many years. It is less hilly than adjacent areas, its night air is more still and the area’s typical evening temperature inversions are stronger there, the report said.

But for the last two years, Lynwood has not exceeded the carbon monoxide standard for a single day, EPA officials said.

Armistead G. Russell, the environmental engineer at Georgia Institute of Technology who was chairman of the panel, also pointed to recent studies which found that carbon monoxide levels below the current standard may be harmful to the elderly, infants and fetuses.

Carbon monoxide impairs blood’s ability to carry oxygen. Many studies have confirmed the link between high carbon monoxide concentrations in the air and increased hospital admissions and early deaths from heart and lung diseases.

Russell said carbon monoxide’s regulatory success has not received much attention because the change took place slowly. Blake Early, a consultant for the American Lung Assn., agreed that the carbon monoxide-reduction success story had been “under the radar.”

Early said he hopes the lessons from it help opponents in the debate over the Bush administration’s plan to replace some provisions of the 1970 Clean Air Act with a program to allow power plants to buy and sell government-issued credits allowing them to generate certain amounts of pollution.

“This is strong evidence that the Clean Air Act is working and not broken,” Early said.