Gretchen C. Genrich, age 9, is chairman of BELTS (Buckle Every Life Tight for Safety), a group that advocates use of seat belts on school buses. Her first name was stated incorrectly in yesterday's Metro section.

The Fairfax County Board of Supervisors voted yesterday to allocate up to $100,000 to install seat belts in as many as 87 new county school buses, while school officials in Montgomery County decided to study whether to equip some new school buses with the devices.

The buses Fairfax County plans to equip with belts are scheduled for delivery this spring. The installation was characterized as a trial by Supervisor Thomas M. Davis III (R-Mason), who introduced the measure.

"It's a wonderful first step," said Karen Genrich, mother of Karen Genrich, 9, and chairman of a group called BELTS (Buckle Every Life Tight for Safety). "I think this will help the rest of the country move in this direction" of having seat belts in school buses.

Last night the Montgomery County Board of Education agreed to study whether 53 new buses scheduled to go on line this fall should have seat belts. The board agreed to ask the County Council to reserve $74,000 in the board's request for an operating budget to supply the new buses with belts if such action is deemed desirable.

The decision came after discussion in which several board members said they were in favor of the protective devices but wanted more information about safety and enforcement.