Dhaka’s air pollution is worsening children’s mental health

Physiologically, children are more vulnerable to the effects of air pollution than adults because their brains, lungs, and other organs are still developing. Photo:Mohammad Minhaj Uddin

Dhaka has consistently ranked among the most polluted cities in global indices for many years. Of specific concern is particulate matter 2.5, or PM2.5, consisting of particles that are 2.5 micrometres or smaller in size. 

To provide some perspective, PM2.5 particles are 30 times thinner than the average human hair and can be inhaled by both adults and children. 

In Dhaka, the concentration of PM2.5 exceeds the World Health Organisation's (WHO) annual air quality guideline value by a staggering 7.8 times, measuring at five micrograms per cubic metre (µg/m3). 

In densely populated and economically disadvantaged areas of Dhaka, the concentration of PM2.5 can be up to 20 times higher than the WHO standard. This means that the air people breathe in Dhaka is currently considered unhealthy and poses long-term health risks.

There is a direct correlation between the size of these PM2.5 particles and the risk of severe health problems. Inhaling these particles can have a detrimental impact on the lungs and heart, leading to issues such as wet coughs, asthma, bronchitis, cancer, and various cardiovascular and neurological diseases. 

If a person's exposure to PM2.5 exceeds WHO's Global Air Quality Guidelines by just 1%, their likelihood of experiencing respiratory problems increases by 12.8%, the chance of developing a wet cough rises by 12.5%, and the risk of lower respiratory tract infections goes up by 8.1%.

A recent report from the World Bank reveals that approximately 20% of premature deaths in Bangladesh are directly attributable to air pollution. It's important to note that even a 1% increase in PM2.5 exposure above the WHO guideline is associated with a 20% increase in the likelihood of experiencing depression. 

According to the Air Quality Life Index (AQLI) proposed by the University of Chicago, air pollution is estimated to reduce the average life expectancy of Bangladeshis by approximately 6.7 years. 

In some of the most heavily polluted districts of Dhaka, Narayanganj, and Gazipur, this reduction in life expectancy can be as high as 8.1 years. 

Studies have shown that PM2.5 particles can accumulate deep within the lungs and be deposited in vital organs through the bloodstream. These air pollutants can lead to inflammation of blood vessels and damage to the blood-brain barrier, which is a delicate membrane that protects the brain from toxic substances. 

Some of the harmful effects of air pollution on mental health include anxiety, depression, Alzheimer's disease, Parkinson's disease, schizophrenia, and bipolar disorder, among others.

Physiologically, children are more vulnerable to the effects of air pollution than adults because their brains, lungs, and other organs continue to develop until adolescence. 80% of lung alveoli, which are tiny air sacs crucial for breathing, are formed after birth, and changes in the lung continue through adolescence. 

Children breathe at a rate about twice as fast as adults, often through their mouths, which leads to a higher intake of pollutants. Additionally, they spend more time outdoors and breathe air closer to the ground, where pollutant concentrations can be highest. 

Several studies conducted in the United States and Europe have shown that exposure to particulate matter is associated with the development of autism spectrum disorder in children. It is also linked to anxiety and depression in children. Air pollution has a more significant impact on children, given their higher exposure to pollutants.

A British-American study conducted on 2,039 children born between 1994 and 1995 in England and Wales over a 25-year period found that children exposed to high levels of traffic-related air pollution had a higher likelihood of experiencing mental health issues by the time they reached eighteen. 

The participants' mental health was assessed for symptoms of ten common psychiatric disorders, including alcohol dependence, anxiety, Attention Deficit Hyperactivity Disorder (ADHD), and more. 

These symptoms were used to estimate their overall mental health situation, labelled the 'psychopathology factor' or 'p-factor.' Children exposed to the highest levels of Nitrogen Oxide (NOx) scored 2.62 points higher than their peers, and those exposed to the most particulate matter scored 2.04 points higher. 

This demonstrates a positive correlation between childhood exposure to NOx and particulate matter and the development of disorders. A similar study conducted at the University of Manchester found that exposure to PM2.5 and Nitrogen Dioxide (NO2) during childhood is associated with a higher risk of self-harm in later years. 

To date, no study has explored the relationship between air pollution (including PM2.5) and the mental health and cognitive development of children in Bangladesh. While there have been numerous studies on air quality across Bangladesh, a 2019 study conducted by the US-based Health Effects Institute found that major cities in Bangladesh exceeded the WHO Annual Air Quality Guideline for NO2 (10 µg/m3). 

Given the deteriorating air quality in recent years, it can be assumed that NO2 concentrations have worsened as well. This raises concerns about the mental health of children in Bangladesh, as observed in studies discussed above, with an expected increase in depression, anxiety, and self-harm.

A team of researchers at the International Centre for Diarrheal Disease Research, Bangladesh (icddr,b) conducted a systematic review of the literature from 1998 to 2004 on the mental health of Bangladeshi children. 

They found a prevalence of mental disorders ranging from 13.4 to 22.9 %, with an estimated prevalence of autism spectrum disorders between 0.2 and 0.8 % in Bangladesh. These numbers are concerning, especially in light of the neglect of mental health in the country's healthcare system.

Bangladesh faces a severe shortage of public mental health services, a lack of mental health experts, inadequate funding, underdeveloped mental health strategies, and social stigma surrounding mental health issues. 

Little research has been conducted to establish a causal link between children's mental health disorders and the country's poor air quality.

A 2022 study by the World Bank reveals that some 40 % of Dhaka's air pollution originates from natural sources and economic activities within its jurisdiction. However, 28 (out of this 40) percentage points of the pollution originate across Bangladesh's borders—mainly from India. The remaining 60 % of Dhaka's pollution emanates from neighbouring districts and divisions. 

The multiple pollutants include dust, dirt, soot, smoke, fumes, and liquid droplets. The main contributors to these pollutants include automobiles, unpaved roads, electricity generation plants, construction sites, factories, and brickfields.

There is, however, scope for optimism. A report by the World Bank in 2023 stated that Bangladesh has hitherto undertaken measures to boost air quality management, including the authorisation of Air Pollution Control Rules. 

Nevertheless, the country has a long way to go, requiring transboundary cooperation, solutions, and solid national actions to curb air pollution.

The World Bank report proposes a three-phase roadmap to improve air quality in Bangladesh. Phase 1 requires setting the parameters for coordination across airsheds, which are geographical areas that hinder the dispersion of pollutants. 

This can be achieved by intensifying air pollution monitoring beyond large cities, sharing public data, bolstering and establishing reliable scientific research organisations to analyse airsheds, and adopting an approach encompassing all government branches. 

Phase 2 involves widening abatement interventions outside nonconventional, and perhaps less popular, targets—such as brick kilns, cooking stoves, farming, solid waste management, and other small firms—to curb their emissions. It is also essential to simultaneously introduce emissions standards across airsheds. 

Phase 3 refines the pertinent economic incentives to encourage the development of solutions from the private sector, ensure economic justice, and formulate and coordinate climate change policies for maximum synergy. 

Pollution reductions across Bangladeshi firms and jurisdictions may be incentivised and streamlined by introducing emissions permits—i.e., 'cap-and-trade.'

Bangladesh must take concrete and proven steps to reduce air pollution, which could save many lives, especially children. Children must be protected from the future consequences of current generations' actions (e.g. pollution). 

Our air pollution indifference will cause mental and physical illness in the next generation. Breathing clean air is a survival right. Those who violate this right should be punished. 

Since children are Bangladesh's future workforce, their mental and physical health should be a top priority. Mental and physical illness hinders children's cognitive development. Lack of cognitive development hinders hard and soft skill acquisition. Economic and social potential in children is eventually harmed. 

This endangers their long-term economic prospects and those of society and the nation. Previous generation actions are expected to cause acute and chronic mental and physical health issues in children. The air pollution in Dhaka and Bangladesh is also expected to shorten their lifespans. 

To achieve several Sustainable Development Goals, Bangladesh must reduce air pollution. These include 'Good health and well-being (SDG 3),' 'Decent work and economic growth (SDG 8),' 'Reduced inequalities (SDG 10),' 'Sustainable cities and communities (SDG 11),' 'Responsible consumption and production (SDG 12),' and 'Climate action (SDG 13). Peace, justice, and strong institutions (SDG 16). 

Victims may receive remedial education, psychological counselling, mental healthcare subsidies, and financial compensation. To improve children's futures, Bangladeshi policymakers and society, especially in Dhaka, must make these difficult, bold, and urgent choices.

Sketch: TBS

Nigharin Aresfin is an Early Childhood Development Specialist. Muhammad Shafiullah is an Associate Professor at the Department of Economics and Social Sciences, Brac University.

Disclaimer: The views and opinions expressed in this article are those of the authors and do not necessarily reflect the opinions and views of The Business Standard.