LLong-term exposure to air pollution may increase the risk of developing Parkinson’s disease, according to a new study led by researchers at the University of Cambridge.
The study, published in Environment International, combined evidence from previously published research to examine whether living in areas with higher levels of air pollution is associated with the development of Parkinson’s disease, Multiple Sclerosis and Motor Neurone Disease.
While air pollution is already known to affect heart and lung health, emerging evidence suggests it may affect the brain and nervous system.
Bringing together evidence from around the world
The researchers conducted a systematic review and meta-analysis, a method that combines results from multiple studies, to provide a clearer picture of the overall evidence. They examined studies investigating long-term exposure to common air pollutants, including fine particulate matter (PM2.5), coarse particulate matter (PM10), and nitrogen dioxide.
Strongest links found for Parkinson’s disease
The strongest evidence was found for Parkinson’s disease, which showed that for every 5 micrograms per cubic metre (µg/m3) increase in fine particulate matter (PM2.5) there was an associated 10% increased risk of Parkinson’s disease. For every 15 µg/m3 increase in coarse particulate matter (PM10) there was an 18% increased risk.
Dr Annalan Navaratnam, and Clinical Research Fellow at IMS Epidemiology, University of Cambridge, said: “There are still relatively few robust studies that explore the link between air pollution and Parkinson’s disease, but even so, it’s becoming clear that there is a link. We found evidence of a link with two types of pollutants in particular, but even though the evidence was inconclusive for other types, this may be down to how the studies were designed.
Limited evidence for Multiple Sclerosis and Motor Neurone Disease
For Multiple Sclerosis and Motor Neurone Disease, the research did not find clear evidence that long-term exposure to air pollution increased disease risk, but there were far fewer studies available for these conditions making it difficult to draw firm conclusions.
The researchers say more studies are needed to better understand if there is an association.
First author Alexandra Tien-Smith from IMS Epidemiology, Cambridge, added:
These findings add to a growing and strong body of evidence of the many adverse health impact of air pollution worldwide ranging from a wide variety of disease across every human organ system to premature mortality
The researchers conclude that reducing long-term exposure to air pollution may form part of wider future strategies to help prevent neurodegenerative diseases, while further research is needed to clarify the how higher exposures put the public at risk.
The research was partly funded by the European Research Council’s Horizon 2020 programme, the European Union’s, Horizon Europe Framework Programme.
To help practitioners and policymakers tackle air pollution in their own regions and cities, Dr Haneen Khreis and colleagues have previously created an open-access interactive tool mapping the effectiveness of over 1,000 unique policy interventions to reduce traffic-related emissions and air pollution.
The interventions include congestion charging, urban transport planning, housing planning, mass transit development, active travel promotion, electric vehicles and low emissions zones, among others.
Dr Haneen Khreis, also from IMS Epidemiology, Cambridge, added:
The message is clear: we need to take action now to improve air quality and help reduce the global burden of disease. Our open access tool is intended to help researchers, practitioners, policymakers and third sector organisations understand the impact of different interventions on everything from traffic emissions and air pollution to human exposure, health impacts and unexpected co-benefits. We hope it aids and empowers those in a position to make a difference to implement effective and meaningful policies.
Reference
A.Z. Tien-Smith, S. Absar, C.B. Rogowski, V. Phillips, Z.J. Andersen, C. Bredell,
K.W. Fung, L. Hong, M. Szybka, J. Woodcock, C. Brayne, H. Khreis, A.M. Navaratnam, Association of longterm outdoor air pollution exposure with incidence of Parkinson’s disease, multiple sclerosis and motor neuron diseases: a systematic review and meta-analysis, Environment International (2026), doi: https://doi.org/10.1016/j.envint.2026.110377