A new health threat: "Thirdhand smoke"
"First came doctors’ warnings about cigarettes. Then came discoveries about the danger of secondhand smoke. Now, a growing number of scientists are raising the alarm about thirdhand smoke — residual chemicals left on indoor surfaces by tobacco smoke," the WashPost's William Wan reports.
Why it matters: "Public health advocates worry that those most vulnerable to the harmful effects of thirdhand smoke are also those who most likely to come into contact with it."