A branch of the United Auto Workers (UAW) unrecognized by Harvard yesterday charged Harvard with endangering the health of workers in three Medical Area buildings.

UAW members said they will deliver a letter to the office of Medical School Dean Daniel C. Tosteson '44 this morning, demanding that the University investigate the ventilation which they claim poses a safety hazard.

Tosteson could not be reached for comment last night, but other University officials said they are investigating workers' complaints.

"Some repairs have to be made," said Mortimer Litt, the Med School's associate dean for educational programs, who is in charge of health and safety in the area.

Med School researchers and members of the UAW Health and Safety Committee said yesterday the delivery of the letter marks a peak in two years of ongoing safety problems in the Medical Area.

Employees said the combination of chemical fumes and faulty ventilation in the Med School's building C gave workers headaches, stomach-aches, and nosebleeds.

Several employees contracted chemically-induced conjunctivitis after complaining in October to the University of headaches and eye irritations they suffered while working in the building, union members said.

UAW officials said the University delayed responding to the complaints until late December, when the toxic chemicals were not being produced.

But Litt said that replies to the complaints were "essentially instantaneous."

UAW officials said their ability to elicit a quick response from the University could help them win recognition to represent all Medical Area clerical workers in an upcoming election.

An election will be held if the National Labor Relations Board, which is currently hearing the UAW's case against Harvard concerning unfair practices, decides in favor of the union.