Pollution could put children at greater mental health risk, study says

woman are going to work.she wears N95 mask.prevent PM2.5 dust and smog, mother and child wearing a mask to protect their child from air pollution and infectious diseases
Air and noise pollution exposure could have an impact on children's mental health. (Getty Images)

Children who grow up being exposed to high levels of air and noise pollution may be at higher risk of mental conditions such as psychotic experiences, depression and anxiety, a new study has suggested.

Researchers from the University of Bristol found that even being exposed to air and noise pollution while in utero can impact brain development.

The study, published in JAMA Network Open, showed that exposure to fine particulate matter, or PM2.5 - which are small particles of solids or liquids that can pass through the lungs and into the bloodstream - was linked to higher rates of depression.

Exposure to noise pollution can also lead to increased anxiety due to higher levels of stress and sleep disruption, the authors said, adding that the "high noise [could] potentially lead to chronic physiological arousal and disruption to endocrinology".

"Noise pollution could also impact cognition, which could increase anxiety by impacting concentration during school years," they said. However, the researchers noted that noise pollution was associated only with anxiety rather than with psychotic experiences or depression.

However, they warned that exposure to PM2.5 in polluted air during pregnancy could be “detrimental” to a child’s mental health "given the extensive brain development and epigenetic processes that occur in utero and during infancy".

Asian child protects himself against air pollution by wearing mouth mask
The health effects of air pollution have long been documented. (Getty Images)

"Air pollution could negatively affect mental health via numerous pathways, including by compromising the blood-brain barrier, promoting neuroinflammation and oxidative stress, and directly entering the brain and damaging tissue."

The researchers, led by author Joanne Newbury, analysed data from 9,065 participants who were born in southwest England from 1991 to 1993, and took into account estimates of nitrogen dioxide, PM2.5 and noise pollution at the participants’ home addresses from pregnancy to 12 years of age.

They wanted to investigate "growing evidence" that exposure to air pollution could be "associated with the onset of psychiatric problems, including mood, affective, and psychotic disorders".

The study found that, at 13 years old, 13.6% of participants reported having experienced psychotic experiences. At age 18, 9.2% reported the same, while at age 24, 12.5% said they had had psychotic experiences.

"Our findings suggest an important role in early-life (including prenatal) exposure to air pollution in the development of youth mental health problems," the authors wrote.

"Air pollution comprises toxic gases and particulate matter (ie, organic and inorganic solid and liquid aerosols) of mostly anthropogenic origin. Understanding the potential effect of air pollution on mental health is increasingly crucial, given the human and societal cost of poor mental health, the global shift towards urban living, and the backdrop of emissions-induced climate change."

The latest study comes after researchers from the universities of Oxford and Beijing and Imperial College London found that long-term exposure to even relatively low levels or air pollution could lead to depression and anxiety.

The 2023 study, published in the Journal of the American Medical Association Psychiatry, found that people living in areas of the UK with higher air pollution levels were more likely to suffer from the mental health issues.

They said at the time that the findings revealed a need for stricter regulations to control air pollution.

The World Health Organisation describes clean air as a basic human right, but highlighted that air pollution is a “significant threat to people worldwide”. Figures show that the combined impact of outdoor and household air pollution leads to seven million premature deaths every year.

The 2021 WHO Air Quality guidelines recommend that annual mean concentrations of PM2.5 do not exceed five micrograms per cubic metre and nitrogen dioxide levels do not exceed 10 micrograms per cubic metre. This represents a halving of the limit in 2005.

However, the UK government passed air quality guidelines last year that allowed for more than double the targets set by the WHO. Ministers approved legislation to allow a maximum annual mean concentration of 12 micrograms per cubic metre by 2028.

View from a tall building in the London Docklands looking towards the City with the brown haze of pollution illuminated by the setting sun.
The UK's air quality guidelines allow for more air pollution than is recommended by the World Health Organisation. (Getty Images)

"When the WHO’s air quality guidelines were published, experts said it may be close to impossible to achieve in some urban areas of the UK, Europe and Asia". However, they added that there is "still a huge amount that can be done to improve air quality and improve emissions".

Professor Frank Kelly, from the MRC centre for Environment and Health at Imperial College London, said at the time: "Air pollution is the biggest environmental threat to human health accounting for 7 million premature deaths every year. The new WHO guidelines, the first update since 2005, provide an update on the damage air pollution inflicts on all ages across the life course. Concerted action to meet the updated guidelines will save lives and reduce the burden of disease.

"Meeting these updated WHO air quality guidelines will be a challenge, especially in many UK cities, but by not doing so will mean our children and generations to follow will suffer from our inaction. Meeting these guidelines will require international cooperation; reducing emissions of pollutant pre-cursors and transboundary pollution that travels across continents.

"Importantly, many of the necessary actions will have additional benefits toward limiting climate change, resulting in a healthier planet and a healthier population."

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