Federal and regional air-pollution specialists launched a new $523,000 study yesterday to assess the risks of public exposure to carbon monoxide, one of the Washington area's most intractable pollutants.

Central to the study is a small, computerized monitoring device designed to measure carbon monoxide concentrations once every second. About 1,000 Washington-area residents will be asked to carry these gadgets for a full day as they commute to work, go shopping and engage in other ordinary activities. The $1,600 box-shaped device, worn by a shoulder strap, is about 5 1/2 inches high and weighs less than 2 pounds.

Carbon monoxide, a colorless and odorless gas, is viewed as a health hazard whose ill effects include dizziness, headaches, nausea, impaired judgment, reduced muscle coordination and, in extreme instances, death. It is produced chiefly by incomplete gasoline combustion in automobiles and is especially prevalent in winter at congested traffic intersections.

The study, financed by the federal Environmental Protection Agency, is meant to help close a significant gap in scientific understanding. "Currently, no reliable information on actual population exposure to carbon monoxide is available," Walter A. Scheiber, executive director of the Metropolitan Washington Council of Governments, said at a news conference. The council has joined with EPA to manage the study.

Most carbon monoxide monitoring in the past has been conducted by devices set up near a relatively small number of traffic intersections or on building roofs, where pollution concentrations are high. Such measurements give no indication of the amount of carbon monoxide to which most persons are normally exposed at their homes and workplaces or as they travel along roads and intersections where monitors are not hooked up.

This lack of data makes it difficult for scientists to determine whether urban areas, such as Washington, are falling short of federal antipollution goals. Federal limits set a maximum of 9 parts per million during an eight-hour period.

Federal officials said the findings from the new study, expected to be completed by next summer, may lead to changes in carbon monoxide regulation in Washington and about 90 other polluted cities.

The study will be conducted both in Washington, which was chosen as a typical "commuter city," and in Denver, where the city's high altitude results in reduced oxygen and increased carbon monoxide. The testing is scheduled to begin next month.

Officials are seeking a cross section of Washington-area residents to take part in the tests, for which each participant will be paid $15. The battery-operated devices they will carry were derived from safety monitors used by coal miners. A tiny pump sucks in air. Pollution is measured through a chemical reaction that generates an electric current whose flow is proportional to carbon monoxide levels. CAPTION: Picture, A $16,000 monitoring device that will be worn by about 1,000 Washington area residents in carbon monoxide study. By Vanessa Barnes Hillian -- The Washington Post