Around one in ten lung cancers in the UK occurs in someone who has never smoked — a group that is rising, largely because smoking has fallen. If something has made you wonder about your own risk — a relative’s diagnosis, a letter about radon, a headline about air pollution — this page sets out which risks are real, which are modest, and the one you can actually test and fix. It also gives an honest steer on when a scan is worth arranging and when reassurance is the right answer. Dr Lawrence Okiror, Consultant Thoracic and Robotic Surgeon (GMC 6150382), reviews patients personally at London Bridge Hospital and The Lister Hospital Chelsea, typically within 2–3 working days. Self-referrals welcome.
Last reviewed: July 2026 · Dr Lawrence Okiror FRCS(CTh) FRCSEd(CTh) · GMC 6150382
Radon is the leading environmental cause of lung cancer in non-smokers — and unlike your genes or your past, it can be tested for around £50 and reduced.
Most raise risk only modestly — a family history in a never-smoker by around 1.25-fold. The real question is not “am I at risk” but “does anything warrant a scan”.
A persistent cough or coughing up blood in a never-smoker deserves the same seriousness as in a smoker. Treating lung cancer as only a smoker’s disease is what causes delay.
Most of what raises lung cancer risk in a non-smoker is fixed history you cannot change — a childhood spent around smokers, an old job, the genes you were born with — and each one, on its own, shifts the odds only modestly. Reading a longer and longer list of them tends to raise anxiety without changing anything. The useful question is not how many risk factors you have, but which of them is worth acting on.
Two answers stand out. First, radon is the one major risk you can measure and reduce — the rest you can only note. Second, and more important, a persistent symptom outranks any risk factor. The corrective to worry is not to scan everyone who is anxious; it is individual judgement about who genuinely warrants a scan and who can be reassured. Dr Okiror reviews patients personally at London Bridge Hospital, typically within 2–3 working days, and arranges a CT scan where it is warranted — and says so plainly when it is not.
Yes — and it is more common than most people expect. Somewhere between one in ten and one in seven lung cancers in the UK occurs in a person who has never smoked. As smoking has declined, this group has become a larger share of the whole, though it is worth being clear why: the rise is driven mainly by the falling number of smokers, not by a large increase in the number of never-smokers affected. The proportion is rising because smoking-related cancer has fallen — context that should reassure, not alarm.
Lung cancer in never-smokers also behaves as a somewhat distinct disease. It is more common in women — around two in three, in a recent Guy’s Cancer Centre study of never-smoker lung cancer — tends to occur at a younger age, and is usually a type called adenocarcinoma that grows in the outer parts of the lung. Many of these cancers are driven by specific genetic changes in the tumour, such as EGFR or ALK alterations, which also open the door to targeted treatments.
That biology, and what it means for genetic testing, targeted therapy and surgery, is covered on the lung cancer in never-smokers page. This page answers the question that brings most people here: if I have never smoked, what actually raises my risk — and should I do anything about it?
Of everything that raises lung cancer risk in a non-smoker, radon is both the most important and the only major one you can measure and reduce. It is a naturally occurring radioactive gas produced by the slow breakdown of uranium in rocks and soil. It seeps up from the ground, accumulates in the lower floors of buildings, and is inhaled with every breath. The UK Health Security Agency identifies radon as the second most common cause of lung cancer after smoking, and the leading environmental cause in people who have never smoked — a cause in around 1,100 lung cancer deaths a year in the UK.
of lung cancer cases are attributable to radon, depending on local exposure levels.
the UK action level. The average home sits near 20; around 5% exceed 200, and more than a third do in some areas.
a three-month home test. Where levels are high, reduction is usually straightforward and effective.
The evidence is clear and unusual in one respect: the relationship is linear with no safe threshold, established from a collaborative analysis of thirteen European studies (Darby and colleagues), with risk rising by about 16% for every 100 Bq/m³ of long-term exposure. If you smoke or have smoked, the effects of radon and tobacco multiply — which is exactly why testing matters most in that group. You can check whether your postcode falls in a radon-affected area, and order a test, through the UKHSA’s UKradon service. It is, quite simply, the one number on this page you can change.
Second-hand smoke is a genuine cause of lung cancer in never-smokers. Pooled international evidence puts the increase at roughly 20 to 30% for someone regularly exposed — around a quarter higher risk overall — and the more, the longer, and the earlier in life the exposure, the greater the effect. For most people in the UK today this is largely a historical or childhood exposure, since smoking indoors and in workplaces has fallen sharply. It is a real factor, not a reason for alarm, and nothing can be done retrospectively about exposure that has already happened.
Air pollution — specifically fine particulate matter, PM2.5 — is a contributor, and the science behind it is genuinely interesting. Work from the Francis Crick Institute (Hill and colleagues, 2023) showed that pollution appears to act not so much by creating new genetic damage as by awakening mutations already present in the lung, through inflammation. But two things keep it in proportion for a UK never-smoker: per person, smoking still carries roughly ten times the risk, and the UK is not among the world’s most polluted places — the global burden of pollution-related lung cancer falls overwhelmingly elsewhere. Air pollution belongs on the list, but not at the top of it here.
Workplace and occupational exposures — asbestos above all, and others such as silica, diesel exhaust and certain metals — are well-established causes, though for most people these too are historical. If you had significant occupational exposure, it is worth mentioning to your doctor, particularly asbestos, which is also linked to a separate condition affecting the lining of the lung.
No. A close relative with lung cancer does raise your own risk — but for a never-smoker the increase is modest, and it is worth seeing the actual size of it rather than the fear of it. Pooled data from the International Lung Cancer Consortium put the risk at around 1.25 times higher for a never-smoker with an affected first-degree relative — a parent, sibling or child. It rises to roughly twofold when the relative was diagnosed at a young age, which points to a genuine inherited component.
Importantly, this familial risk appears to act independently of smoking — it is not simply that families share smoking habits. In practice, the message is straightforward: a family history is a reason to take any symptoms seriously and to mention it to your doctor, and where a relative was affected young it may lower the threshold for investigation. It is not, on its own, a reason to assume the disease is inevitable, nor currently a basis for routine scanning in someone with no symptoms.
For many never-smokers who develop lung cancer, no single cause can be identified — and the honest answer, when patients ask me “why me?”, is that often there isn’t one to point to. The genetic changes that lead to cancer can occur in lung cells by chance, as they can anywhere in the body, without any exposure or behaviour to explain them.
This is worth saying plainly, because the search for a reason can become its own burden. You do not need to have done anything, or to fit a particular profile, to develop lung cancer — and equally, you cannot always prevent it by having lived carefully. That is precisely why the older idea of lung cancer as purely a smoker’s disease is misleading, and why symptoms in someone who has never smoked should be taken just as seriously.
The purpose of this page is not to add to worry but to replace it with a plan. For a never-smoker, the sensible response depends far less on which risk factors you have than on whether you have symptoms — and there is a clear order of priority.
Where circumstances sit in between — symptoms that are hard to place, a worrying family history, a scan already done elsewhere that has left you uncertain — a consultation is often the most useful step. Many people who come with a worry leave with reassurance and no need for anything further. Where a scan has already raised a question, a second opinion can clarify whether it needs action or watchful waiting.
The never-smoker who presents with persistent respiratory symptoms is the group in whom lung cancer is most often missed — because neither patient nor pathway expects it, symptoms can be milder, and a normal chest X-ray offers false reassurance. Two practical points are worth carrying into the consultation: persistent symptoms warrant a CT rather than reliance on a normal X-ray, and a patient in a radon-affected area with symptoms has a modifiable, testable exposure worth noting.
Dr Okiror welcomes referrals and self-referrals, reviews imaging personally, and arranges a CT scan promptly where warranted. Fuller guidance for referring clinicians, including nodule thresholds and the fast pathway, is on the information for GPs page.
Most private patients are seen within 2–3 working days of contacting the practice. Self-referrals welcome — you do not need a GP letter to book, though if you have one it is helpful. Bring any chest X-ray or CT report or images, a list of your symptoms and when they began, and details of any relevant family history or radon testing. Dr Okiror reviews everything personally at the first appointment and arranges further imaging only where it is genuinely warranted.
Book a consultation → · Request a second opinion → · Information for referring clinicians →
Questions most commonly asked by people who have never smoked and are trying to make sense of their own risk. Often a short consultation settles the question more quickly than reading can.
Book a Consultation →Or call Jo Mitchelson:
020 7952 2882
Self-referrals welcome. Private appointments at London Bridge Hospital and The Lister Hospital Chelsea within 2–3 working days. Bring any scan report and a note of your symptoms. Dr Okiror reviews everything personally and gives a clear, honest assessment — including when the right answer is reassurance.
Jo Mitchelson, PA · 020 7952 2882 · pa@lungsurgeon.co.uk
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The fuller picture — why it occurs, genetic testing for EGFR and ALK, targeted treatment, and surgery for people who have never smoked
Too Young or Never Smoked?Why a normal chest X-ray does not rule lung cancer out — and why symptoms deserve to be taken seriously
Lung Nodules & CancerFor patients with a lung nodule of unknown cause — what it is, how it is assessed, and when treatment is needed
Specialist Second OpinionIndependent review of a scan or diagnosis — to clarify whether something needs action or watchful waiting