Since approving an ordinance last April that bans selling cigarettes and other tobacco products in Princeton to anyone under age 21, the town’s Board of Health has been making an effort to enforce the law. The department recently went undercover, with the aid of a teenaged intern, to make sure none of the 16 area vendors that carry these products is violating the new ordinance.

In just two days, the high school student visited each of the retailers, including McCaffrey’s, Molisana, and Wawa markets, Rite Aid, the Exxon station, and several others, and attempted to purchase cigarettes. Health officials were pleasantly surprised to learn that none of the retailers agreed to sell tobacco products to the underage teen.

“I thought we’d be right around the state average, which is 88 percent. But being at 100 percent shows that our inspectors were doing their job educating everybody about the new ordinance,” said Princeton Health Officer Jeffrey Grosser, who reported the good news to Princeton Council on August 10. “We want to reduce tobacco sales to minors and that is what this ordinance does.”

Princeton was the fifth town in New Jersey to enact the law. The legal age to buy cigarettes in New Jersey is 19, but municipalities can adopt their own ordinances to change that age. The fine for violation is $250 for the first offense, $500 for the second offense, and $1,000 for subsequent offenses.

The student who went undercover followed a script when he attempted to purchase the tobacco products. Apparently, he added his own spin to the plan. “I heard that he adopted different accents and different approaches,” said Councilwoman Heather Howard, who is the governing body’s liaison to the Board of Health and the former Commissioner of the New Jersey Department of Health and Senior Services. “He varied the types of things he was buying, too. He would go in while one of the health inspectors waited outside.”

Originally, Mr. Grosser planned to use two or three interns for the undercover effort. “But it was going so well that we only used the one,” he said. “We got permission from their parents first and everything was signed off before we started.”

After the operation was completed, retailers were given a letter of compliance indicating that they had been inspected and found to be obeying the law.

Ms. Howard said she had some concerns that the new rule raising the age to 21 might cause some confusion among retailers. “So the fact that we had complete compliance was very good news,” she said. “Enforcement is where the rubber hits the road. The longer you can prevent youth initiation of smoking, the better it is.”

The town last did an undercover check of retailers selling tobacco products in 2010. Results were not as favorable. In fact, they were below the state average. “So it is a testament to public education and the work of the Department of Health that we’ve reached 100 percent,” Ms. Howard said. “I was surprised with the results, but very happily surprised.”

A report by the Surgeon General revealed that more than 1,200 people in the United States die of smoking-related causes every day, and 480,000 die of it a year. Among adults 18 and older, tobacco use is the single largest preventable cause of death and disease in the United States, according to the Centers for Disease Control and Prevention. In addition, smoking-related illness in this country costs more than $300 billion a year, including nearly $170 billion in direct medical care for adults and $156 billion in lost productivity.