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Harmful substances and cancer - Air pollution and radon

Air pollution causes about 3% of lung cancer cases. We’re currently reviewing this content in the light of the recent announcement by the International Agency for Research on Cancer. In the meantime, please read our blog post about the announcement.

Air pollution is a problem of the industrialised world. It has been linked to heart disease and respiratory diseases such as asthma and bronchitis. But does it affect our risk of cancer?

Outdoor air pollution

Scientists have found that outdoor air pollution does increase the risk of lung cancer.

In June 2012, an international panel of experts concluded that diesel exhaust causes lung cancer. They found limited evidence for a link with bladder cancer. But this is not likely to account for very many cases, especially compared to those caused by smoking.

Much of the evidence that fed into this review came from people who were exposed to large amounts of diesel exhaust through their work. However scientists suggest that pedestrians, drivers and others could also be affected to a lesser extent, and that governments ought to look at ways to reduce people’s exposure to diesel fumes.

The review also looked at petrol exhaust, but they didn’t change their view that it could ‘possibly’ increase cancer risk – that’s to say, there isn’t enough evidence to show a link in humans.

Air pollution vs tobacco smoke

Living in a city or near a main road is not going to affect your risk of lung cancer much if you already smoke. A large amount of research has shown that tobacco smoke is much more dangerous than air pollution.

Tobacco smoke causes around 85% of lung cancer cases in the UK, making it by far the biggest cause of the disease. Compared to this, air pollution causes only a small proportion of cases. In European non-smokers and ex-smokers, between 5% and 7% of lung cancers may be caused by air pollution.

Cycling instead of driving can help to reduce air pollution. Dealing with air pollution

In developed countries, air pollution is much less of a problem than it used to be. Catalytic converters have reduced the levels of particles and nitrogen dioxide in car exhausts. Thanks to better technology and safer Government policies, we are a long way from the smogs of the 1950s.

Local authorities and environmental agencies are responsible for monitoring and responding to pollution levels across the UK. But we can all play a part in reducing levels of air pollution.

You can find out about local pollution levels and get a forecast on the UK National Air Quality Information Archive website. And the Department for Environmental, Food and Rural Affairs website has more information on what the Government is doing to reduce pollution levels.

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

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

Every day, thousands of people in the UK are exposed to second-hand smoke, including 40% of children 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 deposited in the lungs.

Radon is found in the air at a low level outdoors, but concentrations can sometimes build up into high concentrations indoors. And several parts of the UK including south-west England and parts of Wales have much higher concentrations of radon than normal. The Health Protection Agency website has a helpful map of radon levels in England and Wales.

Cancer Research UK scientists have found that exposure to radon accounts for only 3% of all UK cases of lung cancer.

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 less than one in a hundred chance of getting lung cancer. But smokers living in these areas are 25 times more likely to get lung cancer.

High radon levels can be reduced by increasing under-floor ventilation with a fan. This can cost up to £1000 initially, and £50 yearly. New buildings can be made radon-proof at a very low extra cost.

If you are worried, you can find more information on the Health Protection Agency website. You can also see a map of radon levels in the UK or order a radon measurement pack for your home.

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Question about cancer? Contact our information nurse team
Updated: 13 June 2012