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Air pollution, radon and cancer

Air pollution causes about 3% of lung cancer cases. Air pollution is a complex mixture of many different substances and the exact contents vary depending on what sources of pollution are nearby, your location, the time of year and even the weather. 

The main sources of air pollution include transport, industry, fossil fuel power stations, farming and fuels people use to cook and heat their homes. Some pollutants, such as North African desert dust and radon gas, are natural.

Air pollution is often separated into indoor and outdoor situations. Although pollutants from outside can and do travel inside, indoor air pollution is heavily influenced by sources of pollution within the building. 

Around the world, burning fuel for cooking and heating is a big contributor to indoor air pollution. But in the UK, radon gas and cigarette smoke are more likely to be important sources.

Although both outdoor air pollution and indoor pollutants, such as radon, have been shown to increase the risk of cancer, it’s important to keep the risk in perspective. 

Smoking has a much bigger effect on the risk of developing lung cancer than outdoor air pollution or radon does. If you smoke, the best thing you can do for your health is to quit.

Outdoor air pollution

Air pollution is associated with an increased risk of lung cancer. Although the increased risk of cancer is small for individuals, because everyone is exposed to some air pollution, it has an important effect across the population as a whole.

In 2013, the International Agency for Research on Cancer (IARC) brought together a panel of experts to review the evidence on outdoor air pollution and cancer. This panel decided that, based on laboratory research as well as on studies looking at people, outdoor air pollution can cause cancer in people. 

The panel also concluded that there was enough evidence to say that a specific part of air pollution known as PM 2.5 (solid dust-like particles, or ‘Particulate Matter’, less than 2.5 millionths of a metre across) can cause cancer. You can read more about the IARC decision on our blog.

How big is the risk in the UK?

The risk depends on the level of air pollution people are regularly exposed to, but because the make-up of air pollution varies so much, it’s hard to say exactly how much the risk is affected for the people living in a certain area. 

In general, air quality guidelines and the evidence they’re based on relate to specific pollutants. And the best understood of these is PM2.5.  
Cycling instead of driving can help to reduce air pollution.
The risk of developing lung cancer increases as the level of PM2.5 increases. But for PM2.5 levels at the lower end of the scale, such as those typically found in the UK, the increase in risk of lung cancer is likely to be small. PM2.5 is also found in tobacco smoke, and being a smoker exposes you to much higher levels of PM2.5 – and cancer risk – than air pollution in the UK.

A very large study of UK air pollution showed no real difference in the risk of dying from lung cancer between people living in places with the highest PM2.5 levels, compared to the lowest. But this study did find about a 10 per cent higher risk of dying from lung cancer for people with the highest levels of nitrogen dioxide, compared to the lowest. 

Air pollution isn’t only linked to lung cancer, there is also good evidence that it can increase the risk of other diseases, mainly respiratory diseases and heart disease.

How high is UK air pollution?

Compared to other countries around the world, the UK has fairly low levels of air pollution, and for most pollutants it is within the EU limits. 

But some places, especially cities like London and Glasgow, experience higher levels of pollution. This is particularly a problem with nitrogen dioxide, where the UK is in breach of its EU commitments.

Cancer Research UK wants the Government and relevant authorities to introduce measures that reduce air pollution, particularly where levels exceed EU limits, to protect people's health.

What can I do?

As individuals, we can play our part in reducing air pollution levels by trying to avoid creating more of it. Choosing ‘active travel’ options where possible, like walking and cycling, can help reduce pollution levels from transport and is also a great way to be more active, which is linked to a reduced risk of cancer and other diseases.

If you want to find out more, the Department for Environment, Food and Rural Affairs (Defra) have published a useful guide to air pollution in the UK. As well as information on air quality and monitoring, Defra’s UK-air website has air pollution forecasts for your area and the Met Office are starting to include the predicted daily air quality index in their forecasts.


Second-hand smoke is a pollutant and causes cancer. Indoor air pollution

The two most important types of indoor air pollution in the UK are second-hand smoke and radon gas.

Currently, millions of people in the UK are exposed to second-hand smoke and 20 per cent of children report being exposed to second-hand smoke in their own homes. 

Second-hand smoke increases the risk of cancer and other diseases, such as heart disease and stroke, leading to thousands of deaths every year.


Radon is a natural radioactive gas that can increase the risk of lung cancer. When inhaled, it can change into other radioactive chemicals that can be left behind in the lungs.

Radon is found in the air at a low level outdoors, but it can sometimes build up to high concentrations indoors. And several parts of the UK, including south-west England and parts of Wales, can have higher levels of radon. Public Health England’s UK Radon website has helpful maps of radon levels by UK region.

Cancer Research UK scientists have found that exposure to radon accounts for only 3% of all UK cases of lung cancer. The vast majority of radon-related lung cancers are caused jointly by radon and smoking, meaning that these cancers could also be prevented by being a non-smoker.

As with air pollution, radon has a small effect on cancer risk compared to smoking. Even if non-smokers live in areas with the highest concentrations of radon, they still have no more than a one in a hundred chance of getting lung cancer. But smokers living in these areas are over 20 times more likely to get lung cancer.

High radon levels can be reduced by increasing under-floor ventilation with a fan, and there are different options depending on how high radon levels are and whether you have solid or suspended floors. The most expensive options can cost up to £2,000 to install, including fees for a contractor, and then around £50 a year for running costs for the fan. New buildings can be made radon-proof at a very low extra cost.

If you are worried, you can find out more  on the UK Radon website, which has lots of information including how to order a radon risk report or measurement pack for your home or workplace.

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Question about cancer? Contact our information nurse team
Updated: 15 September 2014