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Smoking just a few cigarettes a day damages lungs

A woman is standing next to a no smoking symbol drawn on a sidewalk.

Nov. 15, 2019—When it comes to skirting smoking's dangers, many people think cutting back to just a few cigarettes a day is safe. But no amount of smoking is harmless, as a new study highlights. It found that even light smoking causes lung damage, which could lead to chronic obstructive pulmonary disease (COPD).

COPD makes it hard to breathe. It's diagnosed when a person's lung function (how much they can breathe in and out) drops below a certain level. Everyone—whether they have ever smoked or not—gradually loses some amount of lung function with age, but smoking accelerates the rate.

Similar lung power impacts

The study compared lung function measurements in more than 25,000 people, including current smokers. These included light smokers (people who smoked fewer than five cigarettes a day) and heavy smokers (those who smoked 30 or more cigarettes a day).

A key finding? Both groups of smokers lost lung function at a relatively similar rate. That means that a light smoker could lose as much lung function in a year as a heavy smoker might lose in nine months.

Damage lasts for decades

The study also examined how long it takes for lung function loss to return to normal after smokers quit. It found that while lung function does decline much more slowly in ex-smokers, it takes at least 30 years to reach a nonsmoker's rate.

As a result, smoking's impact on lung function—even from a few cigarettes a day—may persist for decades.

Top takeaways

COPD is typically associated with heavy smoking. But as the authors of this study note, light smoking may pose a greater risk for COPD than anyone realized.

So no matter how much you smoke, it's best to quit completely rather than to just cut back.

And it's also best to quit as soon as possible. The sooner you stop smoking, the more likely you are to reap the most health benefits. That's because it may take longer for ex-smokers' damaged lungs to heal than was previously believed.

The study was published online in The Lancet Respiratory Medicine.

How to prepare to quit

Talk to your doctor if you need help with stopping smoking. You can boost your chances of success by making a plan to quit.

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