Although secondhand smoke exposure in the United States dropped by half between 1999 to 2000 and 2011 to 2012, one in four non-smokers, or 58 million people, are still exposed to smoke, according to a new Vital Signs report from the Centers for Disease Control and Prevention (CDC).

The study assessed exposure using cotinine, a marker of secondhand smoke found in the blood.

Data from the National Health and Nutrition Examination Survey show that declines in exposure to secondhand smoke have been slower and exposure remains higher among African-Americans, those who live in poverty, and those who live in rental housing.

Also reported is that two out of five children ages three to 11 are exposed to secondhand smoke.

“Secondhand smoke can kill. Too many Americans, and especially too many American children, are still exposed to it,” CDC Director Tom Frieden said in a news release.

The study used rental status as a way of identifying people who live in multiunit housing, which is an environment where the issue of secondhand smoke exposure is of particular concern.

“About 80 million Americans live in multi-unit housing, where secondhand smoke can seep into smoke-free units and shared areas from units where smoking occurs,” Brian King, Ph.D., acting deputy director for research translation in CDC’s Office on Smoking and Health, said. “The potential of exposure in subsidized housing is especially concerning because many of the residents — including children, the elderly, and people with disabilities — are particularly sensitive to the effects of secondhand smoke.”

The report credits the overall decline in exposure to several factors. 26 states, the District of Columbia, and almost 700 cities have passed comprehensive smoke-free laws prohibiting smoking in worksites, restaurants, and bars. These state and local laws currently cover almost half the US population. In addition, a growing number of households have adopted voluntary smoke-free home rules, increasing from 43 percent in 1992-1993 to 83 percent in 2010-2011. Also, cigarette smoking has declined significantly in the last two decades and smoking around non-smokers has become much less socially acceptable.

Some of CADCA’s coalitions have already taken that call to action and have worked on implementing policies to address smoking in multi-unit housing. You can download a toolkit here. For tips and strategies to reduce tobacco use in your community, access CADCA’s online Tobacco Use Prevention Toolkit.