Clean Air Day

With Clean Air Day being marked across the UK on 21st June 2018¹, anyone interested in mental health might like to consider the links between poor-quality air and poor mental health. The connection between air pollution and deaths from respiratory and cardiovascular causes is well established in the UK and elsewhere, but Clean Air Day presents us with an opportunity to think about the direct ways in which air pollution might be contributing to poor mental health outcomes too. Is it too far-fetched to think that air pollution could actually cause mental illness?

In 2015, it was estimated that 7.6% of all global deaths were attributable to the presence of fine particulate matter in the air². In the UK, up to 40,000 premature deaths from air pollution are estimated to occur per annum and up to 6 million sick days are attributable to unhealthy air³. With a current mortality gap of over 10 years in the UK between those with and without major psychiatric illness⁴, at the very least psychiatric patients are likely to be disproportionately affected by mortality and physical morbidity attributable to poor air quality.

However, there is now emerging and compelling evidence that air pollution may directly influence adverse mental health outcomes, certainly as far as suicide, dementia and anxiety are concerned. Good quality environmental epidemiological studies have recently started to emerge from across the world outlining a link between suicide and air pollution - particularly pollutants such as fine particulate matter and Nitrogen Dioxide. Recently published research from the Far East⁵, Europe⁶ and the United States⁷ show a small but important effect of short-term increases in air pollution on completed suicides, although the neurobiological and neuropsychological mechanisms that could underpin this are speculative at this stage and largely unexplored^{8 9}.

Anxiety appears to be associated with exposure to high levels of small particulate matter¹⁰, whilst there is increasing evidence that Emergency Department attendances for psychiatric reasons are related to high levels of air pollution¹¹. Finally, a widely reported¹² study published in the Lancet in 2017 showed a substantial increase in the incidence of dementia in people living close to major roads¹³ - the implication being that air pollutants from vehicles were the main mediating factor.

As evidence for the health benefits of cleaner air accrue, it becomes easier to push policymakers into action - this was highlighted earlier this month by the Mayor of London in conversation with the Royal College of Physicians¹⁴.

Of course, an added benefit of reducing air pollution is that CO₂ emissions will also fall - taking the UK nearer to its goal set out in the Climate Change Act of 2008 to reduce carbon emissions by 80% by 2050. Significant physical health benefits have been predicted if we can manage to meet our CO₂ emissions targets¹⁵, perhaps we should be shouting about the potential mental health benefits too? So, as psychiatrists why not use Clean Air Day 2018¹ to promote the health benefits of a cleaner, less polluted environment for us, our communities and our patients.

For more information on the health impacts of air pollution see the  UK Health Alliance on Climate Change, of which the Royal College of Psychiatrists is a member.

Dr Lisa Page

Consultant Liaison Psychiatrist, Sussex Partnership NHS Foundation Trust,

lisa.page@sussexpartnership.nhs.uk

References

1. https://www.cleanairday.org.uk/Default.aspx
2. Cohen et al. Estimates and 25-yer trends of the global burden of disease attributable to ambient air pollution: an analysis of data from the Global Burden of Diseases Study 2015. Lancet 2017; 389:1907-18
3. https://medium.com/@UKHealthClimate/transforming-the-climate-change-narrative-into-one-of-optimism-opportunity-and-relatability-3054640133a8
4. https://www.theguardian.com/society/2013/nov/25/nhs-mental-illness-mortality-rate-gap
5. Kim et al. Air pollution and suicide in 10 cities in Northeast Asia: a time-stratified case-crossover analysis. Environmental Health Perspectives. 2018  https://doi.org/10.1289/EHP2223
6. Casas et al. Does air pollution trigger suicide? A case-crossover analysis of suicide deaths over the life span. European Journal of Epidemiology. 2017 32:973-981
7. Bakian et al. Acute air pollution exposure and risk of suicide completion. American Journal of Epidemiology. 2015: 181:5
8. Chen & Samet. Air pollution and suicide risk: another adverse effect of air pollution? European Journal of Epidemiology. 2017 32:943-946
9. Raguett et al. Air pollution, aeroallergens and suicidality: a review of the effects of air pollution and aeroallergens on suicidal behaviour and an exploration of potential mechansims. Reviews in Environmental Health. 2017: 323(4): 343-359
10. Power et al. The relation between past exposure to fine particulate air pollution and prevalent anxiety: observational cohort study. BMJ. 2015: 350:h1111 doi:10.1136/bmj.h1111
11. Oudin et al. The association between daily concentrations of air pollution and visits to a psychiatric emergency unit: a case-crossover study. Environmental Health. 2018 17:4 DOI 10.1186/s12940-017-0348-8
12. https://www.bbc.co.uk/news/health-38506735
13. Chen et al. Living near major roads and the incidence of dementia, Parkinson’s disease, and multiple sclerosis: a population-based cohort study. Lancet. 2017; 389:718-726
14. https://www.rcplondon.ac.uk/news/london-mayor-sadiq-khan-discusses-air-quality-and-nhs
15. Williams et al. The Lancet Countdown on health benefits from the UK Climate Change Act: a modelling study for Great Britain. Lancet Planetary Health. 2018: 2(5): e202-213 doi: 10.1016/S2542-5196(18)30067-6