The number of Arlington restaurants with no-smoking sections is expected to increase soon as a result of the County Board's unanimous decision last week to urge restaurant owners to set aside such areas on a voluntary basis.

Although nearly half of Arlington's 500 restaurants and fast food outlets have such sections, board members passed a resolution requesting that others with 75 seats or more set aside at least 25 percent of the dining rooms for nonsmokers.

Several board members have said they would have preferred mandating no-smoking sections, but the Virginia Supreme Court has ruled such action unconstitutional. The extent of the voluntary compliance is to be reviewed in nine months, at which time, board members said, they will decide whether to seek some other enforcement tools.

Martin P. Wasserman, director of the county's Department of Human Services, had urged the board's action, saying there is "incontrovertible evidence" of the dangers of passive smoking -- smoke inhaled by nonsmokers in a room.

Wasserman said his department is consulting with various health agencies representing cancer, lung and heart associations about the possibility of giving certificates of appreciation to restaurants that comply with the recommendation for nonsmoking sections, so owners can place them prominently in the establishment.

"The more we can make people think before we light up, the more we may be able to get people to stop," Wasserman said.

The voluntary-compliance approach has been endorsed by the Restaurant Association of Metropolitan Washington.