VANCOUVER, British Columbia, May 24 (UPI) -- Marijuana worsens breathing problems in current smokers with chronic obstructive pulmonary disease, according to a Canadian study.
Dr. Wan Tan, of St. Paul's Hospital in Vancouver, found that among people age 40 and older, smokers were 2.5 times as likely as non-smokers to develop COPD, while smoking cigarettes and marijuana together boosted the odds of developing COPD to 3.5 times the risk of someone who did not smoke either cigarettes or marijuana.
In other words, adding marijuana smoking to cigarette smoking increased the risk by one-third, according to Tan.
The odds of cigarette smokers having any respiratory symptoms were 2.36 times that of non-smokers, while the odds of someone who smoked both cigarettes and marijuana having respiratory symptoms were 18 times that of someone who smoked neither -- an eight-fold jump in risk, Tan says.
"This study suggests an interaction between cigarettes and marijuana smoking. These findings have not been reported before, and they have a big public health implication," Tan said in a statement.
The findings were presented at the American Thoracic Society International Conference, in San Francisco.
