THURSDAY, April 9 (HealthDay News) -- More than half of New York City residents who do not smoke have elevated levels of the residue of secondhand smoke in their blood, says the city's health department.
And that suggests that nonsmokers in the city -- a number the city estimates at 2.5 million people -- are not adequately protected from cigarette smoke, it says.
"This is not what we expected," Dr. Thomas R. Frieden, the city health commissioner and a co-author of the study, told the New York Times. "It is a shocking number."
A study of 2,000 people by the city's Department of Health and Mental Hygiene, published online this week in the journal Nicotine & Tobacco Research, found that 57 percent of nonsmoking adults in New York City had elevated levels of cotinine in their blood, compared with 45 percent of nonsmokers nationwide. Cotinine, a byproduct of nicotine breakdown, is not harmful but signals exposure to tobacco smoke.
Among nonsmoking New Yorkers, 69 percent of Asian adults are thought to have elevated cotinine levels, putting them at the top of the list, according to the study. Lower-income adults were more likely to be exposed to secondhand smoke than those with higher incomes -- 63 percent vs. 54 percent, the study found.
Data for the study came from a citywide Health and Nutrition Examination Survey conducted in 2004, one year after the city's smoke-free air law took effect. The law aims to protect nonsmokers from secondhand smoke at work and in some public places.
"The study provides more evidence of the pervasiveness of secondhand smoke," Jennifer Ellis, a former health department epidemiologist and the study's lead author, said in a news release from the city. "It's not clear why New Yorkers experience more exposure, despite the city's relatively low smoking rate. It may be that living and working in close quarters with one another puts us at higher risk."
Despite the city's smoking restrictions, nonsmokers are still exposed to secondhand smoke on sidewalks, including near buildings, at bus stops and at subway entrances.
Also, people who live in apartments and condominiums might also be exposed to secondhand smoke that drifts from one unit to another in a building, according to Dr. Jonathan P. Winickoff, a professor at Harvard Medical School.
"Smoke doesn't know to stop at a doorway," Winickoff told the Times. "It fills the full capacity of every indoor location in which the cigarette is smoked."
Frieden, who described tobacco smoke as a "toxic pollutant," said in the news release that "most New York City nonsmokers are breathing in dangerous chemicals in secondhand smoke, potentially increasing the risk of cancer and heart disease."
The American Cancer Society has more about secondhand smoke.
SOURCES: New York City Department of Health and Mental Hygiene, news release, April 8, 2009; April 9, 2009, New York Times