How air pollution can cause cancer

air pollution

Air pollution is a 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. Sources of air pollution can be man-made, such as fumes from vehicles and smoke from burning fuels. While others, such as North African desert dust and radon gas, are natural.

Air pollution is often separated into outdoor air pollution and indoor air pollution.

Although both indoor and outdoor air pollutants 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 either outdoor air pollution or radon do. 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 there was enough evidence to say that outdoor air pollution can cause cancer in people.

And 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. 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 it’s hard to say exactly how much the risk is affected for the people living in a certain area. One of the best understood air pollutants is PM2.5, the risk of developing lung cancer increases as the level of PM2.5 increases.

Because levels of PM2.5 are relatively low in the UK this increase in risk for an individual is fairly small compared to other risk factors for lung cancer such as smoking.

An estimated 7.8% of lung cancers each year in the UK are thought to be caused by PM2.5 air pollution exposure.

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. Tobacco is the single biggest preventable cause of cancer, and 86% of lung cancer cases in the UK are linked to tobacco smoking.

You can find out more about air pollution levels in different regions of the UK on the UK-AIR website.

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.

At the moment it is unclear whether NO2 could directly cause cancer. With increasing NO2 concentration the risk of lung cancer also appears to increase, but unlike PM 2.5 it’s not clear how NO2 in itself could be increasing cancer risk. It is possible that NO2, which is mainly given off by road transport, is a marker of other pollutants also given off by vehicles, and that it is these that increase the risk of cancer.

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.

Cancer Research UK wants to see Government and local authorities working together to develop a comprehensive strategy to reduce air pollution 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.

Indoor air pollution

Indoor air pollution can have many sources, including fuels used to heat homes and cook with, tobacco smoke and radon. In the UK, the two most important types of indoor air pollution are second-hand smoke and radon gas.

Second hand smoke

Currently, millions of people in the UK are exposed to second-hand smoke, and for children most of this exposure occurs 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.

Radon is found in the air at a low level outdoors, but it can sometimes build up to high concentrations indoors. Levels of radon vary across the UK, several areas, including south-west England and parts of Wales, may have higher levels. You can find out more about the levels of radon in your region on Public Health England’s  UK Radon website.

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, this means that these cancers could also be prevented by not smoking.

Even if non-smokers live in areas with the highest concentrations of radon, on average only about one in a hundred would develop lung cancer. But smokers living in these areas are over 20 times more likely to develop the disease.

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, 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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