"Almost certainly within five years, virtually all college campuses will be smoke-free," said John Banzhaf, a professor of public interest law at George Washington University and executive director of Action on Smoking and Health, who pushed GW to ban smoking indoors. (It did but resisted his attempt in 2006 to eliminate smoking outdoors as well.)

Michael J. McFadden, a smokers' rights advocate, said he would not argue that smoking is unhealthful for the smoker. But he said the idea of cigarette smoke outside affecting others' health borders on craziness.

"Whatever exposure to 'poisons and particulates' might occur from such contact is dwarfed by the exposures to whatever pollutants waft over the campus from any of the school's parking lots or nearby roads," he wrote in an e-mail.

Some see the ban as a step too far -- a punitive and unfair restriction on something that should be a matter of personal choice. Chewing tobacco, for example, isn't a danger to anyone other than the chewer.

But Karlynn BrintzenhofeSzoc, an associate professor at Catholic University and a clinical social worker who helps people with lung, throat and mouth cancers, said: "I don't think there are any unfair restrictions on choices around tobacco use.

"We have restrictions on how our water has to be cleaned, how our meat has to processed. . . . Putting a restriction on chewing tobacco, which we know is carcinogenic and causes really bad cancers . . . I'd love to see this happen in more schools," she said.

According to the fall 2007 National College Health Assessment, about 19 percent of college students smoked a cigarette in the previous 30 days.

At Georgetown, the percentage of students who said they had smoked one or more days in the past month declined from 16 percent in 2004 to 14 percent in 2008. At the University of Virginia, the figure was about 38 percent a decade ago; this year it was under 19 percent.

At the University of Maryland, the rate is dropping, too, to about 15 percent, with the biggest changes among people who smoked daily. Students today are used to restrictions on smoking, from planes to classrooms to restaurants. And they have been hearing since childhood that their health could be affected by others' smoke.

At U-Md., Kelly Kesler, assistant director of health promotions, said she noticed a real difference in campus culture when she returned to her job after five years away: fewer people smoking outside buildings, tobacco products no longer sold in the convenience store, students more likely to ask someone not to smoke inside, and smokers more conscious that their habit might annoy others.

It was students who started the push at GW to make dorms smoke-free. And when U-Va. officials asked in a survey whether students would like smoke-free restaurants near campus, 40 percent of the smokers supported the idea; less than 20 percent strongly disagreed.