Can Improved Air Quality in Low-Emissions Zones Prevent Lung Cancer?

For many decades, lung cancer was considered the sole preserve of long-term smokers, brought on by the carcinogenic substances in commercial tobacco. But recently, fresh research has discovered links to some of the pollutants found in outdoor air, with an estimated one in ten cases in the UK now thought to be triggered this way. Even though smoking remains the primary risk-factor, claiming around 35,000 lives annually in the UK, these new studies suggest that those 6,000 non-smokers which also succumb to lung cancers may have been impacted by particulate matter in the air. By-products of fossil fuel combustion, these microscopic particles have a pretty dire toxicology profile, with links to dementia, heart disease and cancers. As such, a causal chain begins to take shape from high traffic volumes through degraded air quality to the rates of lung cancer. In the population, prompting many to re-consider the benefits to public health of Low Emission Zones (LEZs), a new scheme in the UK where drivers whose vehicles emit quantities of air pollutants in excess of a certain limit will be fined for the use of roads close to population centres. Perhaps, some pro-LEZ voices have wondered, the proliferation of LEZs across the country could reduce the annual rates of lung cancer.  

As many readers will be aware, there is a fiery debate ranging currently over the planned introduction of an Ultra-Low Emission Zone (ULEZ) in London to enforce even stricter emission standards. Some Londoners say that such a scheme threatens their livelihoods and standards of living as they are unable to afford an upgraded vehicle and require their non-compliant vehicles on a daily basis. As part of a public campaign in support of the scheme, Mayor Sadiq Khan's office has published research into the rates of lung cancer in non-smoking Londoners which includes a worst-case-scenario projection of 955 Londoners currently developing lung cancer every year. If London’s ULEZ goes ahead, this research predicts that only one less Londoner would fall prey to lung cancer – and only in the worst of all possible worlds. Following more moderate assumptions, the models predict no effect. 

As a result, the Labour Party has faced criticism for failing to compellingly advocate for the health benefits of ULEZ. Analysis from the Institute of Economic Affairs, a right-wing thinktank based in London, cites a discrepancy between the decline in lung cancer mortality rates (31%) and falling concentrations of PM2.5 (85%) since 1970, suggesting a weak link between exposure to particulate matter and lung cancer that might cast doubt on the claims of the Mayor’s office. Similarly, the report asked whether there weren’t far more significant health impacts hidden within what the Institute claim are the inevitable economic impacts of the ULEZ, like job losses and increased poverty, all of which contribute to those lifetime stress-levels that can drive the growth of cancers. 

Other investigations, like that carried out by Jacobs Consultants, took a similar reading in a different direction, arguing that whilst the rate of lung cancer may not be significantly reduced, other conditions like asthma and coronary heart disease are likely to fall.  "The Proposed Scheme,” reads the report’s conclusion, “would bring about important reductions in the health impacts associated with air pollution in Greater London and would therefore be an important part of London's overall strategy for improving air quality and limiting the associated health impacts."  

It’s this sentiment that echoes in the responses of the medical community and health charities to the proposed expansion of the ULEZ, with academics like Professor Zongbo Shi, an atmospheric biogeochemist at the University of Birmingham, making the case that health benefits – including a reduction in those pollution-related cognitive difficulties that can ruin productivity –  will ultimately save us all money in the long-run, particularly when it comes to funding the Health Service to deal with the fallout of air pollution.  

So, whilst many have criticised what they view as exaggerations on the part of the Labour Party (and indeed, the Leader of the Opposition, Sir Keir Starmer, has gone public with his support for his Mayor’s line on lung cancer), there is growing evidence of a link between particulates and lung cancer, and it appears that the overall impact of the ULEZ on public health is likely to be positive. Nevertheless, this is only one aspect of an important debate. For many of its critics, public health statistics are unimportant in the face of unwelcome changes to their daily lives, some of which may threaten jobs and push people under the poverty line. It’s a balancing act with no clear end in site.