Fairfax County Board Chairman John F. Herrity was photographed last month when he received an award for being an outstanding publicity seeker, but his aide didn't get the picture.

Several days after the Republican officeholder good-naturedly accepted a Democratic supervisor's award as the "1983 Grandstander of the Year" and posed for the picture, Herrity aide Robert Foreman visited the county information director and asked her please to destroy the negatives. Herrity himself began telling people that he had had the negative destroyed.

Yesterday Herrity said the episode was a joke. "I thought it was funny," he said. "I told some jokes about it--you know, shredding. I guess people took it seriously. That's their prerogative."

The award to Herrity was made by Democratic Supervisor Sandra L. Duckworth, who represents the Mount Vernon District.

County information director Jean Van Devanter apparently was unsure how seriously to take Foreman's efforts. Van Devanter, who declined to discuss the events, went to County Executive J. Hamilton Lambert for advice, according to county officials.

Lambert told Van Devanter to refuse any such requests and said he would talk to Herrity if necessary. "I mentioned it to him later," Lambert said.

"She did the right thing," said Lambert, who noted that the negatives are still intact and the photos available for anyone to see. "We don't do those things here."

Foreman yesterday acknowledged that he had a discussion with Van Devanter, but declined to describe the conversation.

County officials who had heard of the incident said it did not surprise them. "A lot of aides get overexcited in election years," one said.