Minutes after the 2:15 bell had rung, Montgomery Blair High School sophomore Gene Townsend, standing on the school's front porch, pulled the two remaining cigarettes from his pack, lit one and passed the other to a friend.

"It's just stupid," Townsend said of a recent ban on smoking in all county high schools by the Montgomery County school board. That ban is scheduled to go into effect in September. Townsend and a friend are circulating a petition opposing the restriction.

"We're just going to smoke anyway," he said. "The school board should waste its time on better things . . . . If you asked anyone in this school, nearly everyone would say the same thing."

From principals to students to health instructors, the word on the school board's reversal two weeks ago of a 15-year-old policy -- one that permitted high school students to smoke if they have written permission from their parents -- is that while it may be good in its intent it probably will come up short in its enforcement.

The new policy would permit principals to begin enforcing the ban as early as February, but instead of gearing up for a crackdown, many principals said they are waiting to see what the new school board will do once it takes office Dec. 1.

The four new board members campaigned on a platform that supported continuing the current policy.

"We will enforce it if we have to, but that won't make it universally adhered to," said Blair principal Joe Villani, echoing a sentiment voiced by a number of his colleagues.

"Most people would say that it is not a good idea that kids are smoking," Villani said. "But to police it will take a lot of energy and tie up a lot of people over something that is questionable whether it is our first priority."

If the restriction takes effect, Montgomery will become the second school system in the area to ban smoking on all school property. The District already has such a ban. Arlington County, Alexandria and Prince George's County high schools allow smoking in designated areas. In Fairfax County, each school determines its own smoking policy.

Montgomery's school superintendent, Edward A. Andrews, who supported the ban idea, estimates that it will cost $330,000 a year to employ building monitors to enforce it.

Many students who smoke now, however, say that, if the ban is enforced, instead of smoking on school grounds they'll just slip across the street or into a restroom.

"Eventually it will be just like junior high school, where everyone used to go into the bathrooms to smoke or cut classes," Blair junior Marie Tighe said this week. "If we're old enough to buy the cigarettes we should be old enough to make the decision to smoke them."

A number of nonsmokers agreed.

"It's not going to make a difference to the people who smoke now whether they smoke outside or in a bathroom, but it will make a difference to nonsmokers," said Alison Checker, a student at Churchill High School in Potomac. "We won't be able to get near a bathroom. They'll be full of smoke."

Not all students find the new restriction unpalatable, however.

"There are just too many people in this school who smoke," said Blair senior Richard Peck, a member of the school's varsity golf team. "The minute class is over, everyone has their cigarettes ready." At Blair, as at most county high schools, students can smoke outside during the 10-minute breaks between classes.

Andrews and board members who supported the ban have contended that it was not the business of the public school system to make it easier for students to use a proven health hazard and have noted that other school systems have restricted smoking with some success. In particular, Andrews pointed to South Lakes High School in Fairfax County where an experimental smoking ban has been implemented.

South Lakes school officials said there is still some smoking by students there, however.

Few school officials argue with the need to reduce smoking among high school students. Nationwide, the most recent American Cancer Society surveys show that 27 percent of all teen-age girls smoke, an increase over previous years, and that 30 percent of all teen-age boys do. Instead, what most seem to question is the expenditure of enforcement money at a time when funding for public education is being reduced.

Before the Montgomery board approved the measure, the county's council of principals and student representatives both opposed the ban.

"As a taxpayer, I'd just like to see the money spent on something else," said Helen Ryan, a public health instructor at Blair, who last week directed an antismoking movement at the school. Education, rather than policing, is the way to reduce smoking, she said.

However, though most school officials interviewed seemed to agree that there would not be a large-scale decline in the number of secondary school students smoking, some indicated they felt that peer-pressure smoking would be reduced.

"There's no doubt that the number of kids who feel they have to smoke because there was a place to smoke and all their friends were will probably drop," said Villani.

Another school principal, Thomas Marshall of Springbrook, said the rate of success of the new policy will depend on the toughness of the punishment. The majority of principals interviewed said the current policy of not allowing students to smoke unless they have a smoker's card signed by their parents was not enforced.

"At some point it is going to require expulsion," said Marshall. Andrews has recommended that, once the new rule is in place, students who are caught smoking be required to view a cancer film. Other penalties have yet to be determined.