Americans’ exposure to secondhand smoke has declined by half since 2000, federal health authorities reported Tuesday, as states and municipalities banned smoking in bars, restaurants and offices, and fewer Americans smoked inside their homes.The share of American nonsmokers exposed to secondhand smoke fell to 25 percent in 2012 from 53 percent in 2000, according to an analysis of federal health data by the Centers for Disease Control and Prevention.Exposure was determined by testing for cotinine, a marker of nicotine in the blood.
There were many reasons for the decline. Around 700 towns and cities have banned smoking in public places over the past few decades, as have 26 states and the District of Columbia. The report also said that the share of American homes that forbade smoking stood at 83 percent in 2011, up from 43 percent in 1993. Finally, the smoking rate has declined, and smoking has become less acceptable in public.But even with the decline, a substantial share of American nonsmokers — one in four — were still exposed to secondhand smoke. Health experts estimated that such exposure causes 41,000 deaths from lung cancer and heart disease and 400 deaths from sudden infant death syndrome every year.
In all, there are more than 480,000 tobacco-related deaths annually — the single largest cause of preventable death.Secondhand smoke exposure affects African-Americans, the poor and children the hardest. Nearly half of black nonsmokers were exposed to secondhand smoke in 2012, compared with about a fifth of whites. Exposure was far higher among nonsmokers living in poverty — about 43 percent — compared with those who were not poor, at around 21 percent.The age group with the highest exposure was children between the ages of 3 and 11. About 40 percent of that group were exposed to secondhand smoke.Young black children had some of the highest exposure levels, with nearly 70 percent of children ages 3 to 11 exposed to secondhand smoke.
About 40 percent of white children in that age group and 30 percent of Hispanic children were exposed.Children are often exposed to smoke in their homes, and the report speculated that the sluggish decline in exposure of children might have to do with the fact that the fall in the adult smoking rate has slowed.The study also noted that black nonsmokers have higher cotinine levels than nonsmokers of other races. The authors said there was some biological evidence that suggests a slower metabolism of cotinine in blacks, but there were also societal factors. About 26 percent of blacks were exposed to secondhand smoke at their workplaces, for example, compared with 18 percent of whites.