This year marks a decade since the International Agency for Research on Cancer (IARC) gathered in Lyon, France, to unanimously declare that air pollution caused cancer in humans.
Air pollution was classified as a type 1 carcinogen, the most certain category possible. This was mainly based on more than 20 years of research in particle pollution and lung cancer.
The number of research studies has almost doubled since the IARC meeting in Lyon, with even more evidence on lung cancer in never-smokers, but governmental action to reduce air pollution has not kept up.
Globally, outdoor air pollution is second only to tobacco as the greatest cause of lung and respiratory cancers. This holds true in almost all parts of the world, with a notable exception of low-income countries where people (especially women and children) also breathe smoke in their homes from cooking on open fires.
In the past 10 years new studies have linked air pollution to other cancers, including breast and bladder cancer. These have also been associated with nitrogen dioxide, a pollutant from diesel traffic that is being targeted by low emissions zones in many cities. There is emerging evidence of links to childhood leukaemia too.
For those people with lung cancer, smokers and never-smokers, their prognosis and survival appears to be reduced if they live in a polluted area. Research includes a recent study of more than a quarter of a million people with lung cancer in Pennsylvania. This raises questions about the impact of air pollution on the way that cancer progresses and how it may change the effectiveness of chemotherapy.
In 2020, Dr Michelle Turner of ISGlobal, the Barcelona Institute for Global Health, led a review of evidence on cancer and air pollution. She said: “Actions to reduce outdoor air pollution will reduce lung cancer in both smokers and in non-smokers. They may also improve survival from lung cancer, especially in those diagnosed in earlier stages of the disease. A study from the UK’s Francis Crick Institute found that living for three years in an area of higher particle pollution might be sufficient to promote growth of EGFR-driven lung cancer, a type of cancer common in never- and light-smokers.”
Across the UK, about 3,500 cancer deaths were attributed to air pollution in 2015. These are not spread evenly. Air pollution affects us all, but some communities are affected more than others. Greatest concentrations are often found in the poorest communities and also in areas with the highest proportion of black, Asian and multiple ethnicities.
Turner explained: “Recent studies have shown stronger associations of ambient air pollution and lung cancer risk in lower-socioeconomic neighbourhoods where there are higher air pollution levels. There is an urgent worldwide need for multiple, multi-level public health and policy interventions to improve outdoor air for lung cancer prevention and to reduce disparities in the disease”.
Last year the UK set a target to reduce the worst PM2.5 particle pollution in England to 10 micrograms per cubic metre by 2040. The EU is discussing a proposal to meet this target by 2030. This is double the World Health Organization guideline.
Prof Sir Stephen Holgate, from the University of Southampton, said: “Air pollution increases the risk of lung and other types of cancer including breast, liver and pancreas. Overall, the American Cancer Association for Cancer Research states that for every 10 micrograms per cubic of increased exposure to PM2.5, the risk of dying from any cancer rises by 22%.”
