26 February 2016
How Strong is the Link Between Air Pollution and Cancer?
Outdoor air pollution is contributing to approximately 40,000 premature deaths a year in the UK, according to a report from the Royal College of Physicians and the Royal College of Paediatrics and Child Health.
The ‘Every Breath we Take’ report examines the lifelong impact of air pollution on the nation’s health and how polluted air is linked to diseases such as asthma, heart disease, diabetes and cancer.
So how strong is the link between air pollution and cancer? Cancer Research UK says that although exposure to both indoor and outdoor pollutants has been shown to increase the risk of cancer, the risk in the UK is fairly low.
In 2013, the World Health Organisation’s International Agency for Research on Cancer (IARC) decided there was enough evidence to conclude that air pollution “causes cancer in humans,” particularly lung cancer.
But what exactly is air pollution and how reliable is the evidence? Air pollution is a complicated mixture of substances, particles and gases with levels of toxicity very much dependent on the source of pollution, weather and geographical location.
A variety of outdoor and indoor air pollutants are known or suspected to be harmful to human health depending on their concentration. The obvious outdoor suspects are vehicle emissions or pollution from industry and farming, but the main culprit and the subject of most of the research carried out into the health effects of air pollution focuses on particle pollution.
Particle pollution, also known as particulate matter or ‘PM,’ is a blend of dust-sized solids and liquids present in the air that when inhaled, damage DNA inside cells and cause cancer.
The risks associated with PM depend on the level of air pollution people are regularly exposed to. A particular particle known as ‘PM2.5’ commonly found in diesel emissions is known to cause lung cancer and the risk of developing the disease increases depending on the level of PM2.5 exposure.
According to Cancer Research UK, PM2.5 air pollution is responsible for causing an estimated 7.8 per cent of lung cancers in the UK. PM2.5, however, is also found in tobacco smoke, and nearly 90 per cent of lung cancer cases in the UK are linked to smoking.
The IARC assessment reviewed more than a thousand scientific papers and studies from around the world, before confirming that outdoor air pollution is a category 1 cause of cancer. Crucially, the authors of the report say more research is needed as no-one understands how these microscopic particles damage DNA inside cells and whether they are solely responsible for causing cancer.
The problem with verifying evidence on the effects of outdoor air pollution is that it is so hard to measure and depends largely on factors such as whereabouts people live or work and whether they smoke or have smoked in the past.
The good news is that the chances of people in the UK developing lung cancer due to air pollution are relatively small. As with most cancer risk factors, the risk is greater depending on the level of exposure to the hazards in question. Fortunately, it is unlikely that the majority of us will be exposed to high enough levels of outdoor air pollution to make any noticeable difference to our risk of developing lung cancer.
Compared to other countries, the UK generally has low levels of outdoor air pollution although this can of course depend on location. Indoor air pollutants however, are an area that is often overlooked and it is important to recognise the risks of indoor air pollution sources such as nitrogen oxides from gas cooking and solvents released from plastics, paints and furnishings.
The two most important types of indoor air pollution in the UK, however, are radon and second-hand smoke.
Radon is a colourless, odourless and tasteless radioactive gas that occurs naturally in rocks and soil. Radon produces a radioactive dust that becomes trapped in our airways and emits radiation which damages the insides of our lungs, increasing our risk of lung cancer. It is the leading cause of lung cancer among non-smokers and kills more than 1,100 people in the UK every year.
Radon however, is nothing like as dangerous as second-hand smoke, which contains more than 4,000 chemicals, including more than 60 which are known to cause lung cancer.
Second-hand smoke is a well-known direct cause of lung diseases such as lung cancer in both adults and children. If lung cancer is diagnosed early the chances of a positive outcome are significantly higher than if it is found later. But any delays in diagnosis or treatment may cause tumours to spread to other parts of the body. Mistakes in diagnosing lung cancer can be very serious.
Paul Sankey is a clinical negligence solicitor at Slater and Gordon Lawyers in London.
Slater and Gordon help people who have suffered from delayed or wrong diagnosis of cancer due to medical negligence. For a free consultation call our medical negligence solicitors on freephone 0800 916 9049 or contact us online.