World No-Tobacco Day: The best amount of smoking is none
Did you know that smoking fewer than five cigarettes a day damages your lungs almost as much as smoking a whole pack?
World No Tobacco Day is marked each year by the World Health Organisation on 31 May. This year's theme is, "Protecting youth from industry manipulation and preventing them from tobacco and nicotine use". Heart disease, lung cancer, throat cancer, diabetes — the list of bad things that smoking does to your health is long, and growing longer. Thanks to public health warnings and education campaigns, most of us have heard that cigarettes can be dangerous to our wellbeing, and can shorten our life. Although health officials and medical practitioners have long argued there’s no safe amount of smoking, even then many people assume a cigarette here and there doesn’t hurt. A 2019 study published in the Lancet Respiratory Medicine puts that notion to rest: It found smoking just a handful of cigarettes per day causes lung damage similar to smoking more than a pack per day.
Nearly any amount of smoking is bad for lungs
The study examined the smoking habits and health of more than 25,000 people aged 17 to 93. At baseline, each person told the researchers how much they smoked — as well as general information about their health, demographics and lifestyle — and had a spirometry exam, which assesses lung function by measuring how much air can be exhaled in a second, as well as how much air the lungs can push out in total after taking a deep breath. Participants were then tracked for up to 20 years, during which time they had at least one more spirometry test to assess changes in lung health.
Lung function naturally declines with age, but smoking is known to accelerate the process, putting smokers at risk of chronic obstructive pulmonary disease and other respiratory conditions. And as the researchers demonstrate in the Lancet study, nearly any amount of smoking seems to kickstart that effect.
When the study began, about 10,000 of the study participants had never smoked, while 7,000 had quit; 5,800 had vacillated between quitting and smoking; and 2,500 currently smoked. Over time, the researchers found that both former and current smokers had poorer lung function than never-smokers — and there wasn’t a huge difference between the lungs of light versus heavy smokers. Having fewer than five cigarettes per day was associated with about two-thirds as much lung damage as puffing on 30 or more cigarettes per day, according to the study. Put another way, a light smoker could expect to lose about as much lung function in a year as a heavy smoker would in nine months, says Dr Priyank Singh, a Ph.D. in Medicine.
Effects of cigarette smoking on smokers versus non-smokers
Dr Singh says that these findings should dissuade people from taking up any amount of smoking — but it shouldn’t discourage current smokers from reducing their daily cigarette use. Doing so can be an important step towards quitting entirely, and can come with significant health benefits. "The paper reinforces the conventional wisdom that it’s better to quit as soon as possible. Former smokers’ lung function was worse than those who never smoked — even years, and decades after they ditched the habit. It’s possible that smoking-related health risks never fully disappear," says Dr Singh.
There are some caveats to the findings of this study, according to Dr Singh. For example, he says, it relied on self-reported data, which always comes with the possibility of inaccuracy. People in the study also had different numbers of spirometry exams over the years, likely in part because former and current smokers may not have been healthy enough to return for testing, Dr Singh says. "The magnitude of the effects of smoking on lung function alter after adjusting for relevant factors, like the presence of lung disease and exposure to secondhand smoke, but the overall trends [as shown in the study] remain the same," he says.
In the end, Dr Singh says plenty of research, including this one, supports the idea that the best amount of smoking is none. "The most important messages are in many ways ones that we already know: smoking is extremely bad for lung health, and avoiding smoking is the best thing that you can do," he says.