Nearly 1 million Massachusetts residents who don’t smoke and live in apartments or attached houses are exposed regularly to cigarette smoke from their neighbors’ homes, according to a report released Friday by the federal Centers for Disease Control and Prevention.

Nationally, about 45 percent of apartment dwellers—or 29 million Americans—are exposed to health risks from secondhand tobacco smoke, even though they enforce smoke-free rules in their own apartments.

The study, published in the journal Nicotine and Tobacco Research, provides the first estimates by public health officials of the number of Americans experiencing seepage of cigarette smoke into their homes through ventilation systems, loose floorboards, and windows. Researchers relied on a 2009 household survey involving 2 million Americans and 2006 federal tobacco use data both collected by the US Census Bureau.

Advertisement - Continue Reading Below

“These are conservative estimates because it’s very easy to have exposure to significant second-hand smoke without being able to smell it,” said Dr. Tim McAfee, director of the CDC’s Office on Smoking and Health. Surveys indicate that more than half of people who share a wall with a smoker are unaware of cigarette smoke wafting into their homes.

Last September, the Boston Housing Authority implemented a no-smoking policy in all their public housing units. Residents can only smoke outside away from their building and can be evicted for violating the rule. Nearly 26 percent of those public housing residents report that they smoke compared with 14 percent of occupants of private dwellings.

“I heard it’s going well, and they’ve had no problems so far,” said Margaret Reid, director of the Boston Public Health Commission’s healthy homes division. “This is something residents wanted overwhelmingly and we worked with tenants and housing managers for a year to prepare them.”

Apartments and attached houses comprise more than 80 percent of housing in Boston, but there’s no city-wide restrictions on smoking in non-public housing. While Maine recently adopted a statewide no-smoking policy in all its public housing units, Massachusetts and other states have no such bans.

Exposure to second-hand smoke has been associated with a variety of cancers and heart disease in a spate of research studies. “Cigarette smoke contains a toxic stew of 7,000 chemicals and 60 carcinogens, and kids, with their developing lungs, are particularly vulnerable to its effects,” said Danny McGoldrick, vice president for research at the Campaign for Tobacco-Free Kids, a nonprofit advocacy group. “It can increase asthma attacks in those who have the condition.”

The US Department of Housing and Urban Development has “encouraged” owners of subsidized housing units and public housing authorities “to adopt smoke-free policies to protect residents from the dangers of second-hand smoke and to reduce property maintenance costs,” according to a June statement posted on their website. While states and cities have successfully banned smoking in public parks and restaurants, laws restricting smoking in private housing units probably aren’t going to happen in most places.

“I’m not sure anyone’s really suggesting legislation on this one,” McGoldrick said. Instead, advocates and public health authorities have been working on educating housing managers on the benefits of going smoke-free.

About three-quarters of Massachusetts residents who don’t live in a smoke-free building would strongly support the immediate implementation of a no-smoking rule or wouldn’t be against it, according to a 2009 survey of 1,304 local apartment dwellers that was conducted by the Massachusetts Smoke-Free Housing Project. The CDC study found that an estimated 941,000 to 988,000 state residents were exposed to second-hand smoke in their homes despite having personal rules against smoking.

“It has benefits to landlords in terms of maintenance and relocation costs for those who want to move away from smokers,” said Reid, yet many owners aren’t aware that they can legally ban smoking from their building.

The Boston Public Health Commission has established a website called Boston Smoke-Free Homes featuring several thousand private housing units available for purchase or rent that have implemented smoking bans.