In a first of its kind study, researchers at UCSF say people who use e-cigarettes are at a significantly greater risk of chronic lung disease.
Researchers tracked e-cigarette and tobacco habits in 32,000 people between 2013 and 2016. None of the participants had a history of lung disease.
But the study found e-cigarette users were 1.3 times more likely to develop the disease.
The risk doubled for tobacco smokers.
Researchers say using both e-cigarettes and smoking tobacco is riskiest.
There have been other studies on e-cigarette use and lung disease, but those only linked the two at a single point in time, not over a long period.