Mental Health and Air Pollution

Lahore, a city of 11 million people, was engulfed by smog for majority of the winter months. Many have taken to twitter and other social media platforms to complain of headaches, burning eyes, congestion and sore throats. On some days, the global air quality index recorded the highest level of air pollution in Lahore as five times the generally prescribed legal limit.

9 out of 10 people breathe polluted air every day. This year, the World Health Organization has declared air pollution to be one of the greatest environmental risks to health. Microscopic pollutants in the air can penetrate respiratory and circulatory systems, damaging the lungs, heart and brain, killing 7 million people prematurely every year from diseases such as cancer, stroke, heart and lung disease. Around 90 per cent of these deaths are in low- and middle-income countries, with high volumes of emissions from industry, transport and agriculture.

Physical health, cognitive performance, labour and productivity are considered to be more ‘tangible’, and therefore adverse effects if poor air quality on these outcomes are significant and well-established. However, the effects of toxic air impact not just physical health, but also mental health. We have seen a lot of campaigns to reduce the personal and societal costs of mental illness, which include the social environments of individuals, including their personal characteristics, family and romantic relationships as well as their work environment; but it is just as important for public health efforts to also look at facets of the physical environment; such as air pollution. The link between the mental health and toxic air is one which is regularly ignored, and any correlations found are typically dismissed as being simply coincidental and not based on causation.

In one of the first researches aimed to study this link, a study published in the Psychiatry Research journal combined information from a group of children in London with high-resolution data on air pollution levels. Of the 284 children studied, those who lived in the top 25 per cent of the most polluted areas at age 12 were found to be three to four times more likely to have depression at age 18; in comparison to those living in the 25 per cent least polluted areas. The study took into consideration other factors that could affect mental health, such as family history of mental illness, level of income and bullying; and ensured that the results were controlled for these factors. Well-known psychiatrists have also referred to this study repeatedly, explaining that pollutant particles are small enough to cross the blood-brain barrier, and can cause inflammation in the brain, potentially leading to the development of depressive symptoms.

To present a reasonable measure of comparison, data has shown that children who suffer physical abuse are one and a half times more likely to develop depressive disorders as adults. Finding toxic air and pollution to cater for a higher likelihood of mental health impact is therefore quite significant.

Social determinants of physical and mental well-being largely include where you live, and your access to resources and public spaces. Air pollution has therefore also been associated with behavioral changes, such as spending less time outdoors and chosen to adopt a more sedentary lifestyle. Some parents choose to not send their children to school on days that the smog outside is considered unbearable. Such changes, especially in the long-term, have the potential to lead to psychological distress and social isolation. A study at the University of Washington found that the risk of psychosocial distress increased in parallel to the amount of particulate matter in the air. The study surveyed the participants’ feelings of sadness, nervousness and hopelessness through a psychometric scale, to find that neighborhoods with higher levels of pollution scored higher in psychosocial distress. When corroborated, the findings indicated that an increase of 5 micrograms per cubic meter of pollution had the same effect as a 1.5-year loss in education.

More recently, a study in China used real-time data on the people’s mood through social media posts and reactions, and compared it to the amount of airborne particulate matter found in air pollution. Collecting data from over 200 million tweets in 144 Chinese cities, the study found a high association between low levels of happiness, and increased levels of toxic air pollution.

Despite being a newer area of study, the international community has started taking more interest in the links between mental health and air pollution. In October last year, WHO held its first ever Global Conference on Air Pollution and Health in Geneva. Over 70 countries and organizations in attendance made commitments to improve air quality.

It’s about time Pakistan starts taking similar steps – for not just the physical, but also the mental well-being of their citizens.

Published in the Daily Times on 7 February 2019.