Despite an urgent appeal last week to the public for more blood donations, Red Cross officials said yesterday that Washington area blood supplies remain critically low, particularly for blood types in heaviest demand.

Dr. Paul R. McCurdy, director of blood bank services for the Red Cross's Washington chapter, said that local donation centers are collecting fewer than 500 pints of blood per day, although the Red Cross requires more than 600 pints per day to meet the needs of the region's 67 hospitals. The Washington chapter is borrowing from other chapters to close the gap.

"I"ve been here for five years and every summer we have the same problem," said McCurdy. "Eighty-five percent of our donations are collected at work. Then people go on vacation, and the problem is compounded because we tend to have more big users [in the summer] who can use upwards of 50 pints of the same type each."

For example, as of yesterday morning the Red Cross's facility at 2025 E St. NW had on hand 275 pints of Type "O" Postive blood -- the most common type and the most frequently needed. That was about 100 pints short of what the bank needed to send to hospitals. About 1,000 pints were sent in from Red Cross Centers across the country last week to meet the local shortage.

Public response in the past week has helped to ease the shortage for some blood types, said Red Cross spokesman James M. MacLeod. "We have enough Type A, for example. Last week they [the types] were all down to emergency levels. But we have to supply everywhere from Charlottesville to Hagertown, Md. as well as D.C. We are still in need of donors or we'll be in shortage until halfway through September."

According to MacLeod, blood shortages can result in higher costs for patients, and sometimes, resheduled surgery. Surgery is often postponed in the summer, "but at the beginning of September [the number of operations] goes right through the roof, and with it the need for blood," MacLeod said.

Persons wishing to donate blood are urged to go to the Red Cross facility on E Street, which is open seven days a week, 24 hours a day. Donors must weigh at least 110 pounds, be in good health, and be between the ages of 17 and 66. Seventeen-year-old donors from the District and Northern Virginia must have parental consent.