The nose knows: thirdhand smoke alarm.

• Author: Sullum, Jacob
• Position: Citings - Brief article

EVERYONE knows you inhale "secondhand smoke" in a room where someone else is smoking. But what do you inhale in a room where someone smoked the day before? If your answer was "virtually nothing," you are sadly misinformed about the hazards of "thirdhand smoke." Or so say the authors of an article in the January issue of Pediatrics, who were troubled to find that only 65 percent of nonsmokers and 43 percent of smokers "agreed that thirdhand smoke harms children." Then again, the researchers, led by pediatrician Jonathan Winickoff, only just coined the term, so it may take a while to catch on.

The levels of toxins and carcinogens absorbed through secondhand smoke are so much lower than the doses smokers receive that attempts to measure their effects push the limits of epidemiology. The levels in thirdhand smoke are lower...