Cancer Research UK : Harmful substances and cancer

Harmful substances and cancer - Air pollution and radon

Air pollution causes about 3% of lung cancer cases.

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 by a small amount. But what is more strongly linked to other diseases.

A study published in the Lancet, a top medical journal, estimated that outdoor air pollution affects 3% of lung cancer cases in the UK. Many of these cases happen in workers who spend a lot of time on the road and are exposed to large amounts of diesel exhaust.

Traffic exhaust is the main source of nitrogen dioxide.

What does outdoor air pollution consist of?

Outdoor pollution is a collection of many different gases and chemicals. The ones that have the strongest impact on cancer risk are:

· nitrogen dioxide, a brownish-yellow gas · airborne particles (also known as particulate matter or PM), that are small enough to be inhaled into the lungs

Nitrogen dioxide can cause serious damage to our DNA. Vehicle exhaust is the main source of nitrogen dioxide, and can account for three quarters of emissions in large cities.

PM consists of a wide variety of different chemicals, such as soot. Some of these can have direct harmful effects, but the main problem comes from other cancer-causing chemicals that stick on their surface. These can then be inhaled into the lungs.

Air pollution vs smoking

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 smoking is much more dangerous than air pollution.

While air pollution may cause up to 3% of lung cancer cases in the UK, smoking causes up to 90%. This means that smoking causes nearly 30 times more lung cancers than air pollution does.

Cycling instead of driving can help to reduce air pollution.

Dealing with air pollution

In developing 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.

If you can, try to walk, cycle or use public transport instead of using a car. Car exhaust is a major source of air pollution in the UK.
If you have to use a car, try to drive smoothly, keep your tyres at the right pressure and make sure that your engine is properly serviced.

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.

We may not be used to thinking about second-hand smoke as air pollution. But in terms of cancer, it has a larger impact than traffic fumes or industrial emissions.

Every day, thousands of people in the UK are exposed to second-hand smoke, including 40% of children in their own homes. And every year, second-hand smoke kills about 1,500 people through lung cancer and thousands more through other diseases.

Radon

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 1% of all cancer deaths in the UK, mainly from lung cancer.

As with air pollution, radon has a tiny 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.