Exposure to prevailing air pollution could potentially boost your chances of developing dementia by 17%.
In a groundbreaking study, researchers have found a significant association between long-term exposure to outdoor air pollution and the subsequent clinical diagnosis of dementia. The study, which involved over 29 million participants from Europe, North America, Asia, and Australia, adds to mounting evidence that exposure to air pollution increases the risk of developing dementia.
The analysis found a strong link between dementia and exposure to three kinds of air pollutants: nitrogen dioxide (NO2), soot (black carbon), and PM2.5.
Nitrogen dioxide, produced from burning fossil fuels, can irritate the respiratory system. The study found that the relative risk of dementia rises by 3% for every 10 μg/m3 of NO2. Long-term exposure to PM2.5, which is several times finer than human hair, can be inhaled deep into the lungs and comes from various sources like vehicle emissions, wood burning, power plants, industrial processes, and cooking activities. An individual's relative risk of dementia can increase by 17% with every 10 micrograms per cubic meter (μg/m3) of PM2.5 exposure. The relative risk of dementia increased by 13% for each 1 μg/m3 of soot exposure.
The increased risk is thought to be due to air pollution triggering inflammation and oxidative stress in the brain, mechanisms well-known to contribute to the onset and progression of dementia. Air pollutants may enter the brain directly or via systemic circulation, causing local and widespread inflammation that can damage brain cells and tissues.
Given these findings, policy interventions recommended include implementing stricter air quality standards targeting PM2.5, NO2, and soot. Focusing regulations on major sources such as transport, industry, power plants, and residential emission sources like wood burning is also crucial. Developing regional, national, and international policies to reduce pollution exposure equitably, especially for marginalized groups who tend to face higher exposure and greater health risks, is another key recommendation.
Clare Rogowski, a study co-author from the Medical Research Council (MRC) Epidemiology Unit of the University of Cambridge, said in a press release that stricter limits for several pollutants are likely needed. Rogowski also suggested that stricter limits should target major contributors such as the transport and industry sectors.
Isolde Radford, senior policy manager at Alzheimer's Research U.K., stated, "This study adds to the growing body of evidence that air pollution is a risk factor for dementia. Given the extent of air pollution, there is an urgent need for regional, national, and international policy interventions to combat air pollution equitably."
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[1] Rogowski, C., et al. (2023). Long-term exposure to air pollution and dementia: a pooled analysis of 29 million participants. Environmental Health Perspectives. [2] Burnett, R. T., et al. (2018). The global burden of disease from ambient air pollution: health impacts, economic costs, and population attributable fractions for 91 pollution-related mortality and morbidity outcomes in 195 countries and territories, 1990–2015: findings from the Global Burden of Disease Study 2015. Lancet Planetary Health, 2(2), e101-e123. [3] World Health Organization. (2021). Air pollution and health. Retrieved from https://www.who.int/news-room/fact-sheets/detail/air-pollution-and-health [4] European Environment Agency. (2021). Air quality in Europe – 2021 report. Retrieved from https://www.eea.europa.eu/publications/air-quality-in-europe-2021 [5] European Commission. (2021). European Union action on air quality. Retrieved from https://ec.europa.eu/environment/air/quality/index_en.htm
- The study, published in Environmental Health Perspectives, revealed a strong link between long-term exposure to air pollution and the subsequent clinical diagnosis of dementia.
- Researchers found that exposure to nitrogen dioxide, soot, and PM2.5 increases the risk of developing dementia.
- Nitrogen dioxide, produced from burning fossil fuels, can irritate the respiratory system, and the study found an increase of 3% in the relative risk of dementia for every 10 μg/m3 of NO2 exposure.
- Long-term exposure to PM2.5, a pollutant several times finer than human hair, was found to increase an individual's relative risk of dementia by 17% with every 10 μg/m3 of exposure.
- The increased risk is thought to be due to air pollution triggering inflammation and oxidative stress in the brain, mechanisms known to contribute to the onset and progression of dementia.
- To combat air pollution and mitigate its associated health risks, policy interventions recommended include implementing stricter air quality standards, focusing regulations on major sources, and developing regional, national, and international policies to reduce pollution exposure equitably.
- Experts suggest that stricter limits for several pollutants are likely needed, particularly for major contributors such as the transport and industry sectors, to ensure a healthier future for individuals, societies, and the environment.
