George Lowe, 49, of Oxon Hill, was among the first to arrive at the 29th annual Vassar College Book Sale which began at 10 a.M. yesterday. By noon, Lowe - an avid collector of natural history books - had spent $70.05, including his bus fare and lunch money. Then he withdrew an additional $30 from his credit union.

"This is my fourth trip here today," Lowe said, as he rummaged through old books on a table marked "nature." "I've sneaked off from my office. My boss doesn't know where I am. But when the Vassar sale starts I just can't help myself."

Lowe was among the hundreds of book hunters who crowded into a vacant section of the U.S. Department of Transportation building at Seventh and D streets SW in search of Vassar book sale bargains.

Michael Britt and Wayne Morgan, who operate Everyman's Book Store at 3614 12th St. NE. emerged from the crowd with broad smiles and two cardboard boxes crammed with books.

"There are two sales a year worth coming to. That's the Goodwill Industries sale and the Vassar Book Sale," said Britt, as beads of sweat trickled down his face. "We are going to keep a couple of these for our own collection. We'll sell the rest at the store for a handsome profit."

The five-day Vassar College Book Sale, run by volunteer alumni to raise scholarship funds for Washington area students who wish to attend Vassar, is a major annual event for book collectors throughout the East Coast - and beyond.

This year's sale of an estimated 100,000 books is being staged in a 13.000-square-foot section of the federal transportation building, where federal employes by the hundreds and other supporters of the sale quickly packed the room.

At one point, an annoymous complaint that the overcrowding was creating a fire hazard brought D.C. fire inspector M. W. Pitts to the scene. Pitts ordered blocked exits to be cleared, said aisle spaced should be maintained between the book-ladened display tables and limited the number of people who could enter the room at any one time.

Sally Roman (65), this year's chairman of the fund raiser, said early indications are that the sale will attract more people and achieve higher sales than the 1977 event, in which about $45,000 was raised to provide scholarships for 16 Vassar students.

In the 1977-78 academic school year, it cost Vassar students $6,306 to attend the Poughkeepsie, N.Y., institution.

Mrs. Roman said the 1,800 card-board cartoons of books donated for the sale by "all kinds of people all over the area" were delivered to the sale site in two tractor-trailer trucks and a van last week. The books are priced from 50 cents to $1.50.

Evan Vlachos, a Colorado State University professor on a temporary assignment in Washington, collects books on cartoons and political humor. In a few minutes he found 40 of his favorites, which he bought for $33.65.

"I'm a bibliophile. I have about 12,000 books at home," said Vlachos, who lives in Fort Collins, Colo. "My friends had been telling me about the annual Washington ritual - the Vassar book sale. "Now I've seen it for myself. It's paradise."

Before the Vassar book sale ends next Tuesday, George Lowe said he will have spent about $150, the splurge he said his wife allows him during the occasion.