Smoking only a few cigarettes a day doesn’t mean you’re safe from declining lung function. And quitting smoking will improve your lung function, but only to a certain extent, found a recent study by researchers at Columbia University.
The study, published in Lancet Respiratory Medicine, suggests that light smokers who limit their smoking to five or fewer cigarettes a day still have a significant decline in their lung function. Light smokers experienced a decline that was only 32 percent less than that of smokers of up to 30 cigarettes a day. The study also reported that current light smokers are five times more likely to have impaired respiratory function than ex-smokers.
What’s more, while there’s no question that giving up smoking is good for your health, the study found that the respiratory effects of heavy smoking can linger for three decades or more after quitting—challenging past evidence suggesting that quitting smoking before lung disease develops can eventually return lung function to normal.
In the study, people who quit decades ago continued to see a decline in breathing ability compared with people who never smoked. However, the decline in lung function slowed as the length of time since quitting increased, most notably in people who had stopped smoking for 30 years or longer. To reach their conclusions, the researchers analyzed data that measured the amount of air participants could exhale in one second following a deep inhalation. The study involved more than 25,000 study participants (ages 17 to 93).
Our lung function declines in general as we age, but the decline is greater in smokers and ex-smokers—and it could lead to lung disease such as chronic obstructive pulmonary disorder, or COPD, which is characterized by shortness of breath and coughing. Smoking also increases the risk of many serious health problems, including many cancers, strokes, and heart disease.
What you should do
According to the U.S. Surgeon General, there is no safe level of tobacco smoke exposure. If you smoke, the best thing you can do for your health is to quit, which will limit lung damage and reduce respiratory symptoms like coughing, wheezing, and shortness of breath. You’ll also significantly cut your risks for many serious heart problems. Everyone (non- and never-smokers especially) should avoid secondhand smoke as well.
If you’re either a current smoker or a former smoker who’s quit within the past 15 years, are age 55 to 80, and currently smoke or once smoked at least 30 pack-years of cigarettes (an average of one pack a day for 30 years, for instance, or two packs a day for 15 years), talk with your doctor about being screened for lung cancer with an annual low-dose CT scan.
This article first appeared in the January 2020 issue of UC Berkeley Health After 50.