Smokers can be deadweights around the office with lower working performance and more sick days taken than their non-smoking colleagues, two new studies suggest.

In one study, researchers monitored the career progression of more than 5,000 women entering the U.S. Navy between 1996 and 1997. Daily smokers, they found, showed poorer job performances than non-smokers.

Compared with non-smoking participants, frequent tobacco users were more likely to quit before serving their full term, were involved in more incidents of early discharge due to bad behavior and displayed a higher rate of personality disorders, researchers report in the current issue of the journal Tobacco Control. . .

(A second) study team found that, overall, non-smokers took the least amount of days off while smokers took the most sick leave, an average of 11 extra days—more than 2 full-time work weeks. After adjusting for type of job plus health and socioeconomic factors, they reported the difference in sick leave between smokers and non-smokers to be about eight days, or 1.5 work weeks.