I am super excited to be part of the writing team for the Royal College of Physicians’ report, A breath of fresh air: responding to the health challenges of modern air pollution. I would like to thank Professor Sir Stephen Holgate, Dr Suzanne Bartington and Dr Gary Fuller and the core RCP team for the opportunity to contribute to this report.
MY SECTION (3.2 OF THE REPORT) WAS ON AIR QUALITY POLICY AND BRAIN HEALTH, including mental health and dementia, based on the policy agenda my team and I recently outlined for the journal Environmental Research – see below. For more on our work, in addition to the above article, see InSPIRE, our research and policy consortium for mitigating the impact of air quality and environmental exposures on brain health.
OVERVIEW
The RCP’s new report highlights new evidence gained over the last decade showing that there are now links between air pollution and almost every organ in the body and the diseases that affect them.
According to the report, around 30,000 deaths per year in the UK are estimated to be attributed to air pollution, with an economic cost of £27 billion in the UK due to healthcare costs, productivity losses and reduced quality of life. When wider impacts such as dementia are accounted for, the economic cost may be as high as £50bn.
The new RCP report is an update to the 2016 joint Every breath we take report from the RCP and Royal College of Paediatrics and Child Health (RCPCH). It sets out new evidence gained over the last decade about the health harms of air pollution even at low concentrations. We now know that air pollution exposure in early life is linked to poor health later in life and that it impacts foetal development, cancer, heart disease, stroke, mental health conditions and dementia.
Indoor air also poses a growing concern, requiring considerably more attention. People spend the majority of their time in buildings, but there are few standards for pollutant concentrations in indoor air. Poor ventilation, damp and mould and emissions from domestic heating, gas cooking and cleaning products can all contribute to poor health.
It also highlights the links between air quality and health inequalities, showing that air pollution disproportionately affects those from more deprived or vulnerable backgrounds.
Put simply, there is no safe level of air pollution, and increasingly ambitious action needs to be taken to improve air quality across the country to reduce avoidable deaths and improve the health of our population.
The report sets out 19 recommendations aimed national, regional and local governments across the UK, industry, regulators, the NHS, clinicians, and individuals in society.
3.2 Air quality policy and brain health
3.2.1 The impact of air pollution on brain health
As discussed in Part 1, a major addition to the air quality literature – and a fast-growing topic of study – is the impact that air pollution has on brain health across the life-course. Of particular concern is the effect of exposure to air pollution at critical stages in our lives, such as on early-life cognitive development, as well as the effect of cumulative exposure across time, such as on the development of dementia, cognitive frailty and Parkinson’s disease.1–4 More broadly, air pollution is also associated with general mental health issues such as depression and anxiety and is also an identified risk factor for schizophrenia and personality disorders.5,6 Its impact on people who have existing brain and mental health vulnerability is an additional concern. While most studies focus on the increased mental health risks resulting from air pollution exposure, research has begun to explore the post-diagnostic impact of air quality. For example, there is now strong evidence that air pollution exposure contributes to dementia progression and Alzheimer’s disease deterioration.7–9 Research also suggests that for people with dementia, air pollution exposure can have an impact even at concentrations below the current US EPA annual standard for PM2.5 of 9 μg/m3, and well below the limits of the UK (20 μg/m3) and the European Union (25 μg/m3).10
3.2.2 Interactions between air pollution, inequalities and mental health
As outlined in Part 2, pre-existing or ongoing vulnerability is not just biological or psychological, it is also social. The impact of air pollution on brain and mental health appears to be interwoven with the wider determinants of health, including systemic inequalities, pre-existing public health vulnerabilities, the built environment, transport, discrimination and entrenched socio-economic deprivation. Examples include how the causal loop between poverty, living near an industrial air pollution source, and social inequalities across the lifecourse impact upon cognitive decline and neurodegenerative disorders in older, urban populations. Or, how air pollution exposure in early life impacts adolescent global cognition, on account of poor health behaviours, limited access to green space, living in congested housing with poor indoor air quality, and walking to school on busy more polluted roads.11 People living in poverty due to mental health disorders are more likely to have additional breathing issues, making them more susceptible to the impact of air pollution. The places where people are born, live, work and grow old matter very much in terms of the quality of air they breathe and its effects on their brain and mental health.
3.2.3 The need for brain health to be built into air quality policy
Current public policies have been developed to mitigate the impact of air pollution on a variety of health outcomes – from asthma and heart disease to chronic obstructive pulmonary disease (COPD) and lung cancer. However, their implications for brain and mental health are only just beginning to be explored.12,13 There is a need for new policies that specifically address mental health, given that the effects of air pollution on the risk factors for vascular dementia and Alzheimer’s disease for example (such as dose response, pollutant mixture, pathways to disease), differ from those for exacerbating lung disorders such as asthma and COPD. In 2022, Castellani et al published the first policy agenda for mitigating the impact of air pollution on brain and mental health, including dementia. They identified three policy domains – research and funding; education and awareness; and policy evaluation – and 14 priority areas, each of which contain a set of immediate to long-term actionable items (See the Figure here and in the report). Some of these priority areas are explored further here.
1. Rethinking funding.
2. Ensuring that the effects of air quality on brain health are recognised in existing environmental health strategies.
Policies directed at environmental health, such as clean air strategies, green urban planning, improving public transport, transitioning to net zero policies, healing ecosystems and promoting better diet and exercise also include benefits for brain and mental health. For example, third sector and governmental organisations focused on dementia or neurodegenerative diseases should emphasise the importance of clean air for brain and mental health. Similarly, school systems focused on cognitive development should consider that the impact of idling cars at drop-off and pickup, for example, is damaging to a young person’s brain.14,15 The sheer volume of cars on the roads not only increases air pollution but also stops parents from allowing their children to travel to school independently.16 Alternatively, clean air strategies could include improved mental health and wellbeing among their benefits, and link these to climate change and urban development strategies.
3. Engaging in co-production and participatory research.
Air quality is one of the more politically charged global social problems that affects communities worldwide. The politics of air quality are due, in part, to news and social media misinformation, the lobbying by industry and corporations, voting practices and vote share across different groups, the agenda of different political parties, the challenges of public transport, regressive car taxes on people on lower incomes, the complex ways in which clean air strategies are intertwined with economics and workforce issues, and the inability for citizens to directly see air pollution’s influence, particularly in the case of long-term impact. Given these ‘political’ complexities and associated power imbalances, inequities and inequalities, it is vital that stakeholders at local, regional or national levels are involved in developing this policy area. This will ensure that the conflicting needs of governments, businesses, organisations and citizens are kept at the forefront of policymaking and evaluation, which is crucial to removing barriers and improving levers to change.
4. Targeting policy at key points in the life-course.
with the two most important being early life, when brain development and mental health are critical, and later life, when people are more vulnerable due to ageing processes and the cumulative impact of lifetime exposures are evident. Improving indoor air quality in schools, homes and care homes is a good example, or requiring social and private landlords to install heat pumps to reduce both fuel poverty and carbon emissions.
5. Understanding the post-diagnosis impact of air quality on dementia and other mental health and brain-based disorders.
While the research on this topic is still in its early stages, if air pollution is found to accelerate certain brain or mental health disorders for specific groups of people, it would offer the potential for major advances in secondary and tertiary prevention, which would not only help to improve the lives of people, but also significantly reduce healthcare expenditure.
3.2.4 Summary
The link between air pollution and brain health, including early-life cognitive development and later-life neurodegenerative disorders such as dementia, Parkinson’s disease and cognitive frailty should be taken seriously and needs further research. The mental health burden of air pollution is not just an increase in diagnosed psychiatric disorders, but also a worsening of mental health in general. It disproportionally impacts vulnerable populations experiencing poverty, inequality and deprivation. Future air quality policy needs to recognise and aim to mitigate the impact of air pollution on brain and mental health.
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