Feature: Why air pollution is the world’s biggest public health issue

From respiratory illnesses to heart disease, the world’s toxic air is quietly killing millions each year. Leading health experts speak to Martin Guttridge-Hewitt about an urgent crisis policymakers can no longer ignore. 

When the World Health Organization (WHO) published its Global Strategy on Health, Environment, and Climate Change in February 2020, the message was clear. We are rapidly running out of time to mitigate and reverse the devastating environmental impact of industrialisation and urbanisation, which, alongside widespread loss of species and habitat, directly causes 13 million deaths each year.  

The figure accounts for one quarter of all human fatalities. A range of factors contribute to this, but none are more concerning than air pollution, now responsible for the annual loss of 7 million lives. Unsurprisingly, where people live significantly impacts the risk. Poorer communities are most vulnerable because lower cost homes are often closer to polluting infrastructure than higher value properties. Globally, Swiss air quality specialist IQAir ranks 35 cities in India among the 50 most polluted on Earth, with levels of toxic fine particulate matter (PM2.5) on an average day in New Delhi double that of Beijing, itself a metropolis notorious for smog. 

In Europe and North America air quality has improved, helping reduce worldwide PM2.5 exposure to some degree. 94% of the world’s population breathed this in circa 2010, falling to 90% by 2016. Nevertheless, this year alone has seen public health warnings issued for English cities including London, Newcastle, Leeds and Hull due to dangerous air pollution. Even in Scotland, the UK country with the cleanest air, only two towns rank ‘good’ for air quality: Dunfermline and Renfrew.  

‘We really need to focus not just on deaths, which is traumatic and huge, but also emphasise this is reducing quality of life years for many people around the world due to chronic disease… The cost of this to health systems is huge,’ says Dr. Maria Neira, WHO’s Director of Public Health and Environment, explaining this means people suffering impaired mobility, pain, and other symptoms on several days, weeks or months each year. ‘Whether you die from malaria or exposure to air pollution, both are terrible losses. But people always want to compare. So, if we put malaria, tuberculosis, HIV and AIDS together, [air pollution] is bigger. It’s like tobacco, and we have a legally binding treaty for that.’  

Currently, the same cannot be said for air pollution. The WHO recently updated advice on what constitutes ‘safe air’, slashing advisory limits on PM 2.5 and other key pollutants. Countries including the UK, US, and several EU members have scrambled to change legislation to reflect this, although so far none aim to match the organisation’s recommendations this decade. And, sadly, without a global agreement any action at regional or national level will only offer marginal results due to the fact air pollution travels. Simply put, a universally binding agreement on tackling toxic air is essential and cannot come soon enough given the myriad associated health issues. 

People suffering moderate to severe asthma are 40% more likely to experience acute episodes on high air pollution days. Ella Adoo-Kissi-Debrah is a tragic example of this, a nine-year-old who lived near London’s busy South Circular road and became the first person in the UK to have air pollution listed on their death certificate following a fatal asthma attack, leading the coroner to call for UK regulations to meet those of the WHO. Elsewhere, new research by Nanjing University and the University of Macau suggests PM2.5 actually changes the structure of our bodies. The joint study shows particulates severely compress lung tissue, blocking vital cytotoxic T-cells from attacking tumours in their early stages, allowing them to develop unhindered. And respiratory diseases are just one part of the story.  

‘[Another] area we need to worry very much about, but at the moment are super calm on, is the neurodevelopment of children. You see all of these young parents taking incredible care of their children, then taking them to school in a car and keeping the engine on. The pollution generated around that is something that needs to be explained much more,’ Dr Neira replies when asked for examples of less obvious health risks from air pollution. ‘Another is pregnant women. We’re trying to protect them from infections, dangerous foods, but we are not aware that if they breathe polluted air particulates it can close the placenta barrier and damage the development of the brain in the womb. Some of this will only manifest in adulthood — diabetes, non-communicable diseases, and of course low IQ.’ 

The WHO is not alone in trying to raise awareness and pressure policymakers locally, nationally, and internationally. In January 2020, the British Heart Foundation launched its You’re Full of It campaign to try and highlight the link between air pollution and cardiovascular disease. Dr Mark Miller is Senior Research Fellow at the British Heart Foundation Centre for Cardiovascular Science at the University of Edinburgh and is quick to explain that breathing in a toxic atmosphere directly damages organs such as the heart.  

‘It is now well established that air pollution is associated with a wide range of cardiovascular conditions, including heart disease, heart failure, stroke, abnormal heart rhythms and blood clots,’ he says. ‘Scientists have a good understanding of the biological processes by which air pollution detrimentally effects the function of our heart, blood and blood vessels, and these processes will make many cardiovascular conditions worse. It is also clear that air pollution is linked to other major risk factors for cardiovascular disease like high blood pressure and diabetes. The interactions between air pollution and other risk factors for disease worsens health inequalities in our society. There is an urgent need to reduce air pollution and the cardiovascular effects associated with it.’ 

Based on the evidence, it’s impossible not to understand Dr Miller and Dr Neira’s concerns. The air pollution death toll has long been unacceptable, and ‘baking-in’ significant future health problems is a terrifying reality. With that in mind, the real question is at what point do we take meaningful collective action, rather than individual incremental steps which, in the long run, represent the costliest of all options.  

This article first appeared in the May issue of Air Quality News – read it in full here.