Smokers take an additional eight days of sick leave a year and are more likely to perform poorly in the workplace compared with nonsmokers, according to two new studies published yesterday.

Smokers in Sweden took extra days off sick compared with their nonsmoking colleagues, researchers at the Free University of Amsterdam said. A separate analysis of the career progression of women entering the U.S. Navy found tobacco users performed worse than nonsmokers.

Tobacco is the second major cause of death in the world, claiming one in 10 adults, and the fourth-most-common risk factor for disease, according to the World Health Organization in Geneva. People who smoke tend to choose riskier jobs and have poorer health, researchers said.

In the Swedish study, Petter Lundborg and colleagues analyzed national data on sickness absence in 14,000 workers between 1988 and 1991. Smokers took an extra 11 days off compared to nonsmokers, which was adjusted to eight days to account for the nature of their jobs and underlying health.

Smokers took an average of 34 sick days a year, compared with 20 days taken by those that never smoked, and 25 days taken by former smokers.