It was the biggest media event at the Fairfax County Massey Building in recent memory-bigger, even than two displays of recycling toilets in the carpeted board room where the county Board of Supervisors makes laws.

The occasion yesterday was a press conference on gashol, the blend of 90 percent gasoline and 10 percent alchol, that its supporters say could significantly reduce America's dependence on foreign petroleum.

The arranger of yesterday's event, which attracted officials from the Department of Energy, Commerce Department, Capitol Hill and Richmond, was John F. Herrity, chairman of the Fairfax Board of Supervisors-and, incidentally, the impressario of the toilet exhibits.

With an assortment of television cameras pointed at him, Herrity presided at the head of a long table adorned with a Johnnie Walker Red Label scotch bottle. The bottle was filled with ethanol (grain alcohol) courtesy of Mo Campbell, secretary-treasurer of Mar-Cam Industries Inc., in Pennsylvania, one of the few ethanol manufacturers in the country.

It is perhaps unlikely that the Fairfax government will play a decisive role in whether Americans-or even Fairfax Countains-will shift to gasohol, but Herrity has become an unabashed enthusiast for the hybrid fuel.

"After using a couple of tanks of gasohol," he told the meeting, "I'm convinced it works. I'd like to see a product [used] that can stretch our gasoline supply."

By bringing together federal, state and congressional officials with representatives of the gasoline industry, including retailers, Herrity hopes to move toward his goal: 40 to 50 stations in the county that will offer gasohol. Now there are only two.

Leading an effort in Richmond to get favorable legislation and help arrange a meeting with Gov. John N. Dalton will be State Del. Warren E. Barry (R-Fairfax), who sat next to Herrity at yesterday's conference.

Herrity also wants the county to use whatever influence it has to help gasoline jobbers and stations cut through federal red tape and get additional allocations. At the meeting, Herrity also promised fast action on the special-exception permit that the A. Smith Bowman Distillery in Sunset Hills, outside of Reston, needs to get into ethanol production.

The distillery, whose representative was at yesterday's meeting, is considering producing several thousand gallons of ethanol daily.

While gasohol advocates see their product providing up to 10 percent of the 100 billion gallons of fuel used annually in American vehicles, so far the hybrid accounts for only a miniscule fraction of that amount and there is a shortage of plants that can produce ethanol.

After yesterday's meeting, it was unclear on how far the gasohol movement was advanced. But Herrity, who recently announced he was running for a second term as chairman, had for a second term as chairman, had obviously found an issue that would do him no harm.

"I have no regrets about getting favorable publicity about anything I do. That's part of my job."