New research finds smokers inhale enough of their own secondhand smoke that it's like consuming several extra cigarettes per day.
Doctors from the National Cancer Research Institute in Italy studied smokers who worked in enclosed areas. They took air samples to measure exposure.
Results in the journal Environmental Health showed that the accumulation of secondhand smoke was adding a little more than 2 1/2 cigarettes a day.
Researchers say most studies haven't even considered the possibility that passive smoking could be an added health risk for smokers.
