One-third of the 3,050 fulltime firefighters in the Washington area should be removed from active duty because they are physically unfit to do their jobs, according to a University of Maryland study presented at a meeting of the International Association of Firefighters yesterday.

The average firefighter here is overweight, has a low endurance level and has poor muscle flexibility, according to test results on 100 randomly selected firefighters.

"They are the mirror image of society . . . which is poor" when it comes to physical fitness, said Charles Dotson, research director of the sports medicine and physical fitness center at the university, "but these individuals in particular should have a higher than average level but they don't."

The report was delivered during the first day of a two-day symposium at the Shoreham Americans Hotel on occupational health and hazards of fire service. The symposium is being sponsored by the firefighters association.

The association found in its own separate survey that almost half of the 100 firefighters who died last year at the scene of fires died of heart attacks.

Of the remaining deaths, five occurred in traffic accidents involving firefighters on their way to fires while the rest died from such things as collapsing walls, burns and smoke inhalation.

Although the job of the firefighters has become more demanding in terms of physical stress, few firefighters and few of the cities they work for emphasize the importance of keeping firefighters physically fit, said association president W. Howard McClennan.

According to Dotson, the University of Maryland tests also revealed "a direct correlation between ability to perform tasks and weight" - the more overweight a firefighter, the poorer he scored on the tests.

Also, Dotson said, it appeared "from casual observation" that firefighters who smoke tended to score lower than nonsmokers.

The 100 local firefighters selected for the Maryland study were tested for their ability in five basic firefighting tasks. One-third scored in the "excellent" or "good" category and one-third were rated "average." The remaining third scored in the "fair" or "poor" range and were thus considered unfit for their jobs, according to Dotson.

The five tasks performed by the firefighters included extending a ladder, carrying a 72-pound section of hose up five stories, pulling a hose from the ground floor to the fifth floor, chopping a door down and dragging or carrying a 117-pound dummy from the fifth floor of a building.

These tests were performed while the firefighters were dressed in full firefighters gear including a face mask. The gear weighed 52 pounds for each firefighter. The tasks were not conducted in an actual fire, and there was thus no heat or smoke factor.

The tests, Dotson said, will help in designing a new physical performance examination to measure the ability of prospective firefighters and also keep veteran firefighters in shape.

A new test is needed, Dotson said, because recent court decisions have invalidated physical examinations used in several jurisdictions on the grounds that they were not sufficiently related to the job of firefighting and discriminated against women.

Dotson said he and his colleagues, Paul Davis and Laine Santa Maria have taken the abilities required for the five firefighting tasks and translated them into tests involving pushups, long jumps and grip strength that could be used in evaluating job applicants. The new tests discriminate only against the unfit, Dotson said, not women or minorities.

Some firefighters listening to Dotson yesterday said they fear the imposition of physical fitness requirements may be used to fire unfit firemen. "We now hide these people in fire prevention," said one firefighter, "We hide most of them, except for the chiefs."