WASHINGTON (Reuters) - Nonsmokers married to smokers have a greatly increased chance of having strokes, according to a U.S. study published on Tuesday showing yet another hazard from secondhand smoke.
Being married to a smoker raised the stroke risk by 42 percent in people who have never smoked compared to those married to someone who never smoked, the researchers said.
This jumped to 72 percent for former smokers married to a current smoker, according to the study published in the American Journal of Preventive Medicine.
Former smokers who were married to smokers had a stroke risk similar to people who themselves were smokers.
"Quitting smoking helps your own health and also the health of the people living with you," Maria Glymour of Harvard School of Public Health in Boston and Columbia University in New York, who led the study, said in a telephone interview.
The study involved 16,225 people aged 50 and up who had never had a stroke. They were followed for an average of nine years.
Glymour said there is accumulating evidence about the number of health problems linked to secondhand smoke.
Previous research had suggested that secondhand smoke increases the risk of stroke, but Glymour said stroke risk has been studied more extensively in smokers than in people exposed to secondhand smoke.
People who breathe in secondhand smoke also have a higher risk of lung cancer, nasal sinus cancer, respiratory tract infections and heart disease, among other conditions.
A 2006 U.S. surgeon general's report said secondhand smoke contains hundreds of chemicals known to be toxic or cancer-causing. These include formaldehyde, benzene, vinyl chloride, arsenic, ammonia and hydrogen cyanide.
For this study, smoking involved cigarettes and not pipes or cigars. It looked at health consequences for the spouses of smokers, but not at the long-term stroke risk in children of smokers due to secondhand smoke.
"We know that there are a lot of undesirable health consequences for kids, especially asthma and breathing problems that are exacerbated by secondhand smoke," Glymour said.
Editing by Maggie Fox