Study links air pollution to mental, physical illness
New research from the University of St Andrews has found that long-term exposure to air pollution is associated with a higher incidence of both mental and physical illness. The study, which examined 16 years of health and pollution data in Scotland, found links between cumulative exposure to several pollutants and hospital admissions for respiratory, cardiovascular and infectious diseases, as well as mental illness and behavioral disorders.
A team led by Dr Mary Abed Al Ahad from the School of Geography and Sustainable Development reviewed data on the health effects of long-term exposure to ambient air pollution. Previous research has focused more on deaths than hospital admissions and on physical rather than mental health, the researchers said.
The study analyzed individual-level data from the Scottish Longitudinal Study, which represents 5% of Scotland’s population and includes demographic information linked to census records. In total, 202,237 people aged 17 and above were included. Their health and hospital admissions for all causes, cardiovascular, respiratory and infectious diseases, as well as mental illness and behavioral disorders, were tracked using Public Health Scotland data from 2002 to 2017.
The researchers linked the data to annual residential exposure to four pollutants associated with road traffic and industry: nitrogen dioxide (NO₂), Sulphur dioxide (SO₂), particulate matter of 10 μm or less (PM10) and fine particulate matter of 2.5 μm or less (PM2.5).
Pollutant levels fluctuated during the study period, with higher concentrations recorded between 2002 and 2004. From 2002 to 2017, average levels of NO₂, SO₂, PM10 and PM2.5 were 12, 2, just over 11 and just over 7 μg/m³, respectively. Average annual levels of NO₂, PM10 and PM2.5 were below the 2005 WHO guidelines, although NO₂ and PM2.5 exceeded the more recent 2021 WHO guidelines.
Higher cumulative exposure to NO₂, PM10 and PM2.5 was associated with increased hospital admissions for all causes, as well as cardiovascular, respiratory and infectious diseases. After accounting for cumulative exposure over time, respiratory disease admissions increased by just over 4% and just over 1% for every 1 μg/m³ increase in PM2.5 and NO₂, respectively.
The study also found links between air pollution and mental health. NO₂ exposure was associated with a higher incidence of hospital admissions for mental illness and behavioral disorders, while SO₂ was mainly associated with respiratory disease admissions.
The researchers cautioned that exposure was assessed annually rather than monthly or daily, which may have masked seasonal variations. Residential postcodes were also used as a proxy for individual exposure.
The findings are published in the open-access journal BMJ Open. The researchers said stricter environmental regulations, long-term planning and greater use of renewable energy could reduce the health burden associated with air pollution. They also pointed to measures such as zero-emission zones and incentives for renewable energy in transport and energy production as potential ways to reduce exposure.
Category: Education
