A new study shows that smokers take two to three more sick days per year than those who don’t, costing billions of pounds worth of lost productivity.

The study, published this week in the journal Addiction, shows that smokers are 33% more likely to miss work than non-smokers and missed an average of 2.7 more days of work per year. Current smokers were also 19% more likely to miss work than ex-smokers.

“Quitting smoking appears to reduce absenteeism and result in substantial cost savings for employers” said Dr. Jo Leonardi-Bee, study co-author and professor of epidemiology at the University of Nottingham.

The new research looked at 29 other studies conducted between 1960 and 2011 in the U.S., Europe, Australia, New Zealand, and Japan. These studies covered more than 71,000 employees from both the public and private sectors.

The new study also found that £1.4 billion was lost in the U.K. due to smokers’ work absences. In addition, Leonardi-Bee stated that other costs could include cigarette-related fire damage and lost productivity to smoking breaks.

Researchers emphasized that their findings should encourage smokers to quit, to help reduce lost work and improve health. However, they added that further study would be needed to see what smoking cessation interventions might be cost-effective for employers.