Can bad air quality cause anxiety, asks new study

Can bad air quality cause anxiety? Long-term exposure to low levels of air pollution caused by burning fossil fuels increases the risk of developing anxiety and depression, a joint study by UK and Chinese researchers has found.

The study, published in the Journal of American Medical Association Psychiatry earlier this month, followed a group of around 390,000 people based in the UK over a period of around 11 years, and took into account other factors such as socioeconomic status and pre-existing mental illnesses of participants, as well as age, sex and proximity to main roads.

It found joint exposure to multiple air pollutants including fine particulate matter (PM 2.5) and nitrous oxides (NO2 and NO), which are commonly emitted by burning fossil fuels in power plants, industrial processes and transport, is associated with higher risk of depression and anxiety.

Moreover, the risk of developing depression and anxiety tended to be steeper at lower air pollution levels and plateauing at higher exposures.

While further research is needed to identify how pollution negatively affects mental health, it is believed that exposure to pollutants affects the central nervous system by causing inflammation, leading to the development of mental illnesses, the researchers said.

Researchers found a correlation between these mental illnesses and pollution even at levels below the UK air quality standards suggesting that “stricter standards or regulations for air pollution control are essential.”

Clean Air Act

The new Clean Air Act implemented in 2022 in the UK sets targets of 12 μg/m3 for PM2.5 and 40 µg/m3 for NO2 higher than the median concentrations referred to in the study (9.9 and 26 μg/m3 respectively).

“Both pollutants come from the combustion of fossil fuels with road transport being a main source of NO2 and PM2.5” and “domestic wood burning contributing to PM2.5 pollution as well,” Stefan Reis, head of atmospheric chemistry and effects at the UK Centre for Ecology & Hydrology, told Gas Outlook.

“An added complication for PM2.5 is that not only direct emissions of this pollutant play a role in ambient air pollution, but the ‘secondary’ formation of PM2.5 from gaseous substances” including nitrogen oxides, sulphur dioxide and ammonia “leads to further pollution which can be transported through the air” over hundreds of kilometres, he explained.

While “UK air quality, aside from some hotspot areas in large cities or at very busy road links, tends to be better than most industrialized countries” due to the UK being an island and mostly getting cleaner air across the ocean, with UK air pollution being transported across to continental Europe, “the opposite can happen in cases where air masses are coming across from Europe,” he said.

“In spring, this may often lead to episodes of high PM2.5 concentrations stemming from secondary particles formed in Europe from agricultural and combustion emissions, leading to spring peaks of concentrations across the UK.”

Access to green spaces

“The burning of fossil fuels is contributing to the climate emergency but also to mental health problems,” Lisa Page, associate registrar for sustainability at the Royal College of Psychiatrists in the UK, told Gas Outlook.

“Access to green spaces and clean air has the potential to improve the mental health of our population.”

“Emerging evidence shows a connection between exposure to air pollution, and risk of suicide, dementia and other serious mental illnesses,” she said.

“Studies also suggest that long-term exposure to unclean air can contribute to depression and anxiety and make it more likely that people will need mental health services” she continued. “We are deeply concerned by this.”

The Royal College of Psychiatrists and other health organizations have called on the government to tackle this issue by adopting a legally binding commitment to reduce the UK’s fine particulate air pollution level, in order to reach the World Health Organization’s interim target of 10 µg/m3 by 2030, with a future objective to achieve the WHO recommended guideline of 5 µg/m3.

“We must also transition from fossil fuels to renewable energy if we are to mitigate the impact of climate change,” she stressed.

“This will not only be good for the environment but will also improve people’s health and reduce the pressure on mental health services,” she added.