Light, Ex‑Smokers Have Almost the Same Lung Damage as Heavy Smokers
“At least I’m not smoking a pack a day,” cuts no ice with our respiratory systems anymore because new research has found the lungs of ex-smokers and light smokers (<5 cigarettes a day) show almost the same rate of damage as the lungs of heavy smokers.
This new finding is especially relevant because light smokers might also be as likely as heavy smokers to develop respiratory diseases like chronic obstructive pulmonary disease (COPD), which is diagnosed when lung function drops below a certain threshold.
The study, published in the journal The Lancet Respiratory Medicine, analyzed the amount of air a person can breathe in and out (lung function) of 25,000 people aged 17–93 years, who were either light smokers, heavy smokers, ex-smokers, or non-smokers. Researchers also controlled for the fact that lung function in human beings declines naturally from one’s 20s. Such a large number of participants allowed researchers to differentiate between the rate of decline in lung function of light and heavy smokers, which has not been looked at before, as most research only focuses on heavy smokers.
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“Many people assume that smoking a few cigarettes a day isn’t so bad,” study leader Dr. Elizabeth Oelsner, an assistant professor of medicine at Columbia University’s Vagelos College of Physicians and Surgeons, said in a statement. “But it turns out that the difference in loss of lung function between someone who smokes five cigarettes a day versus two packs a day is relatively small.”
According to the study, if the rate of lung decline in a non-smoker hypothetically equaled zero, a light smoker’s lung decline rate would be 7.65ml/year and a heavy smoker’s lung decline rate would be 11.24ml/year. A light smoker could lose the same amount of function in a year that a heavy smoker loses in nine months.
Apart from this, the study also found that quitting cigarettes does not make a massive difference to lung function that it’s touted to make. After quitting, an ex-smoker’s lung decline rate would need 30 years to reach that of a non-smoker’s. “There are anatomic differences in the lung that persist for years after smokers quit and gene activity also remains altered,” Oelsner said.