Pharmacies in unincorporated areas will no longer be able to sell tobacco under a new law unanimously approved by the board of supervisors on Tuesday. Supervisor Susan Adams said she proposed the ban to address the contradiction in pharmacies selling medication for the damage smoking causes, like asthma, lung and heart disease, diabetes and addiction, alongside cigarettes themselves. “There is no safe level of smoke inhalation. It continues to be the number one cause of deaths both in the country and in Marin,” Dr. Larry Meredith, the director of the Department of Health and Human Services, told the supervisors. “With just a few exceptions, pharmacies worldwide are tobacco-free, and it is time for the United States to have pharmacies focus on health.” Inspired by a similar ordinance passed in San Francisco in 2008 and C.V.S.’s recent announcement that it would voluntarily end tobacco sales, Marin’s law will cover smokes, chewing tobacco and electronic cigarettes at four retail outlets when it takes effect in October: West Marin Pharmacy in Point Reyes, Safeway in Strawberry Village, C.V.S. in Sausalito and Walgreens in Mill Valley. Bob Curry, a coordinator for the county’s tobacco programs, said the law will benefit young consumers especially, who will no longer see cigarette ads when they purchase snacks after school or accompany their parents to pick up prescriptions. “Most importantly, they will no longer be receiving the contradictory message that tobacco use is condoned by our health care product retailers,” Mr. Curry said. The new ordinance won’t have much effect in West Marin. Zsuzsanna Biran, the local pharmacist, hasn’t sold cigarettes since she first bought the business in 2007. “It was the very first thing I did when I walked into the store. I threw the cigarettes in the trash,” she said. Joining with Smoke-Free Marin Coalition, the American Lung Association and the Marin Pharmacists Association in support, she wrote a letter calling the ban the only ethical choice for protecting her patients’ welfare. Ms. Biran used to smoke herself, but now she’s certified in smoking cessation therapy. “What a nightmare it is. I quit eight times. I don’t want to feed that addiction for anyone else,” she said. “And it’s certainly pretty hard to smoke if you don’t have cigarettes.”