Smoking is now widely recognised as one of the most damaging habits for human health.
It causes permanent lung damage, increases the risk of almost 40 types of cancer and can dramatically shorten a person’s life.
Quitting can be painful, difficult and take time. For some smokers, the challenge feels pointless: around one in three believe stopping will not help because the ‘damage is already done’.
However, experts speaking to Our News Outlet say the evidence points in the opposite direction.
Giving up cigarettes sharply lowers the risk of dying from lung and heart disease. Quitting early enough can even allow the body to reverse much of the harm caused by smoking.
Pioneering research has found that people who stop smoking by the age of 35 face roughly the same risk of dying from cancer as those who have never smoked.
Stopping by 44 avoids about 90 per cent of the associated health risks, while quitting by 54 can prevent 78 per cent of the risk of dying from smoking-related cancer.
The findings may seem surprising, considering the severe effects smoking can have throughout the body.
Pop star Dua Lipa, 30, admitted to being an avid smoker in 2024 – though said she has attempted to quit
Experts say the growing body of evidence should motivate smokers to quit while there is still time to undo much of the damage caused by the habit.
‘Smoking is the biggest killer in this country,’ says Sir Richard Peto, emeritus professor of medical statistics and epidemiology at the University of Oxford.
‘You can combine every reliably established cause of cancer in this country, apart from smoking, and it still would not come close to causing the same number of deaths.
‘What we now know for certain is that stopping smoking at 30 avoids almost all of the risk of being killed by it. Quitting works, even well into middle age.
‘Our bodies are capable of repairing themselves. But they need to be given the opportunity.’
Although smoking rates among young people have fallen in recent decades, with just 2 per cent of teenagers now taking up the habit, more than five million people still smoke a cigarette every day.
Among them is pop star Dua Lipa, 30, who acknowledged in 2024 that she was an avid smoker, while also saying she had tried to quit.
Research indicates that lifelong smokers live an average of 11 years less than people who do not smoke.
Lung cancer accounts for three in five smoking-related deaths. It kills more than 35,000 Britons each year and is 30 times more likely to affect smokers than non-smokers.
Every cigarette exposes the lungs to more than 7,000 chemicals, including 70 known to directly cause cancer. These substances can damage DNA.
Smoking also harms the heart by damaging the delicate inner lining of blood vessels, which can lead to swelling, inflammation and narrowing.
Carbon monoxide in smoke, likewise, binds to haemoglobin in the blood, depriving the body of oxygen.
As a result, smokers also face a nearly four times higher risk of stroke, as well as an increased likelihood of elevated blood pressure, higher cholesterol and fatty plaque build-up.
And more recent studies have even linked smoking cigarettes to debilitating neurological diseases such as multiple sclerosis (MS) and motor neurone disease (MND).
Though now considered common knowledge, the link between smoking and cancer wasn’t proven until the 1950s, when two British epidemiologists, Sir Richard Doll and Sir Austin Bradford Hill, published the groundbreaking British Doctors Study.
The paper, which asked more than 40,000 doctors about their smoking habits, was revolutionary – changing both public opinion and policy around smoking.
Participants who smoked heavily were found to have a roughly 20 times higher risk of lung cancer than that of non-smokers – with risk rising directly with cigarette consumption. As many as two-thirds of life-long smokers, furthermore, were predicted to die as a result of the habit.
But ten-year follow-ups of the study, published by Professor Sir Doll and Professor Sir Peto, have also revealed something equally important, say experts.
Tracking the health outcomes of doctors who continued to smoke, or quit smoking, as well as those who had never smoked at all, it found that as much as smoking raised the risk of lung cancer, quitting reduced it.
Stopping at age 40, 50, or 60 gained each participant around nine, six or three years back, respectively, from the decade lost from smoking.
Stopping by the age of 30, meanwhile, virtually reset the health risks to that of a never-smoker.
The findings were later reinforced by another large-scale British study – the UK Million Women Study.
Tracking the mortality and medical records of more than 1.3million women across Britain, researchers found that, like men, women who smoke persistently into middle age have triple the death rate of non-smokers.
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Smoking, they calculated, caused the loss of at least 11 years of life expectancy.
But quitting before the age of 30 avoided 97 per cent of this tobacco-related risk.
Follow-ups of the British Doctors Study by Professor Sir Richard Peto (left) and Professor Sir Richard Doll made another key finding: quitting smoking reduced the risk of lung cancer
‘Not only is smoking cessation ridiculously effective, it’s also remarkably quick,’ explains Professor Prabhat Jha, Nuffield professor of population health at the University of Oxford.
‘Studies have shown that if you’re a long-term quitter – having not smoked for ten years or more – you get back almost all of that lost life that you wouldn’t have if you’d continued.
‘And it takes just three years for half of those gains to accumulate.’
This occurs, say experts, due to the body’s remarkable ability to rapidly heal itself once it’s no longer dealing with a daily onslaught of toxic chemicals.
Roughly 20 minutes after having a cigarette, heart rate and blood pressure drop to normal levels, while 12 hours later, carbon monoxide levels in the blood drop, allowing oxygen to circulate properly.
Within 48 hours, the nicotine is totally cleared from the body, allowing nerve endings to begin to re-grow – improving the sense of taste and smell.
It takes another three months for blood circulation and lung function to improve – while a year after quitting, the risk of coronary heart disease drops to half that of a continuing smoker.
By ten years on, the risk of dying from lung cancer also falls to about half that of a smoker – and the risk of stroke returns to that of a non-smoker.
While the body is capable of repairing itself, warns Professor Sir Peto, it does only have a certain amount of reserve. The earlier you do quit smoking, the better it’s able to do so.
‘Chemicals in cigarettes damage DNA in cells in the lungs, and while these chemicals will disappear from the body a day or two after you smoke, this damage will persist for decades,’ he explains.
‘To become cancerous, however, the same cell essentially needs to be damaged twice. Continuing to smoke raises the risk that this will occur.
‘It doesn’t depend on what age you are when you start smoking. Someone who smokes from 20 to 40 and quits will have the same risk of lung cancer at 60 as someone who smokes from 40 to 60 and quits.
‘But someone who smokes from 20 to 60, without quitting, will be at much higher risk of cancer than both groups.’
The findings don’t suggest that one can smoke up until a certain age with no repercussions, experts are keen to emphasise.
A study from US researchers this year found that social smoking in your 20s could still leave you at risk of lung cancer decades later – damaging the lungs just as much as those who go through multiple packs a day.
And a similar paper from researchers at Seoul National University Hospital in Korea found that starting to smoke before the age of 20 raised the risk of stroke even decades after quitting.
Likewise, studies show the longer one smokes, the harder it becomes to quit, as the body becomes more accustomed to and dependent on nicotine.
‘Quitting in your 40s, for example, doesn’t totally get you back to the risk of a never-smoker – there’s still been some harm done,’ explains Dr Rob Hynds, senior research fellow in epithelial biology at University College London.
‘You’re still exposing yourself to all those harmful things – and a lot of those chemicals have an effect on the body even in very low concentrations. So never being exposed at all is vastly preferable.
‘But stopping by 40 does get you 90 per cent of the way there. There’s a huge benefit in terms of your risk in stopping before that age.’
And it takes quitting totally to see a difference – one or two cigarettes a day, at any age, can still be dangerous, research shows.
‘People often think that light smoking – having a couple of cigarettes a day, or a pack when out over a weekend – is harmless,’ says Dr Hynds.
‘But the risk of even that one cigarette is disproportionately high. That person smoking one a day still has roughly a 50 per cent higher risk of coronary heart disease and 30 per cent higher risk of stroke than a non-smoker.
‘That’s only half the risk of smoking 20 cigarettes a day – not, as you might think, one 20th of it.
‘Reducing your intake, or only smoking occasionally, does not proportionally reduce the risk of health issues. The only way to do this is by quitting completely.’
Professor Peto agrees, emphatically. ‘Being a light smoker is the most dangerous thing a person can do,’ he says. ‘Being a heavy smoker is more dangerous. But smoking any amount at all will continue to raise your risk of death.’
As for vaping, while the long-term effects are still unknown, experts say it’s hard to see it being as dangerous as smoking.
‘We don’t know the long-term effects of being a vaper,’ says Professor Jha. ‘But we do know they’re far less harmful than cigarettes.
‘So the advice is currently that the lesser of two evils is vaping. But only as a way to quit smoking – not as a lifestyle in itself.’
