The Washington area's Council of Governments has begun a new procedure that should substantially reduce the number of air pollution alerts here this summer without reducing auto emissions or exhausts.

The procedure, which follows federal guildelines, does not affect the air but changes the standards and terms used to describe it.

For the past two years, pollution index readings above 100 meant the air was officially designated as "very unhealthy." Such readings triggered an air pollution alert.

Under the new reporting system, which went into effect during weekend, readings above the 100 mark are labeled merely "unhealthful." The new system was adopted to conform with the federal requirements calling for nationwide standardization of pollution reporting.

Under the new system, when pollution readings reach the 100 mark, COG will issue a "health advisory," but not an alert.

On Jan. 26, the federal Environmental Protection Agency relaxed the nation's smog standard. Under the old system, COG reported a reading of 100 and called an "alert" when the level of ozone - Washington's major pollutant - reached 0.1 parts per million.

Based on the EPA ruling, the new threshold - not for an "alert," but for a "health advisory" - is 0.12 parts of ozone per million parts of air, which is 20 percent higher.

The term air pollution "alert"will remain in the local texicon, however. Alerts are to be imposed under the new system when the new index rises above the 200 mark.

That mark corresponds to 0.2 parts of ozone per million parts of air, or to an ozone level twice as high as that which triggered the old-style "alert."

The new alert will now have a different meaning. It will signify air that is regarded as "very unhealthy." According to COG, it will signal the need for specific actions to reduce pollutant emissions.

Ozone, which in sufficient concentrations has been associated with headaches and respiratory distress, is produced by the action of sunlight on motor vehicle exhausts.

According to the federal guidelines, readings above 100, signifying "unhealthful air," mean that persons with existing heart or respiratory ailments should reduce physical exertion and outdoor activity.

The "health advisories" that COG will issue in place of the old alert will warn those sensitive to pollution that levels have been reached that might affect their health.

Although the threshold for the new "alert" is twice as high as for the old one, it has been attained here in the past. Readings ashigh as .225 parts per million - 12.5 per cent above the threshold - have been recorded.