Every morning, we take a deep breath while walking outside and feel that we are inhaling fresh air, but the reality is different. The air we breathe is a silent killer. Air pollution, one of the greatest threats of our time, is impacting the quality of our life while jeopardising human health, ruining our ecosystems, and impeding economic growth.

Air pollution refers to the presence of harmful substances, such as gases, particles, and biological molecules that contaminate the atmosphere. While some of it arises from natural events like volcanic eruptions and wildfires, human activities are the main culprits. The exhaust from our vehicles, the smoke from our factories, and even the open fires in rural kitchens contribute to a concoction of pollutants that poison the air.

In Bangladesh, the situation is dire. Cities like Dhaka consistently rank among the world's most polluted places. According to IQAir’s 2022 World Air Quality Report, Dhaka’s average annual PM2.5 concentration is 77.1 µg/m3, far beyond the World Health Organisations’ (WHO) safe limit of 5 µg/m3. These fine particles, invisible to the naked eye, lodge deep into our lungs, causing irreparable damage. Globally, the numbers are not good. The WHO estimates that air pollution causes over 7 million premature deaths annually, with billions exposed to unsafe air quality levels. The Centre for Atmospheric Pollution Studies (CAPS) analysed Air Quality Index (AQI) data of Dhaka for the last nine years (2016-2024). The analysis reveals that the highest pollution levels were observed in 2022 and 2023, which persisted into 2024. The lowest AQI averages were observed in 2017 and 2020, with values standing at 146 and 145 respectively.

The reduced pollution levels in 2020 were attributed to lockdowns that temporarily curtailed major sources of air pollution. Seasonal trends were also identified, showing January as consistently having the highest AQI, averaging 250 across the nine years, except in 2022. In contrast, the lowest AQI values were recorded in July (89) and August (98). Besides January, other months with high pollution levels included November (177), December (218), and February (221), indicating heightened air pollution during the winter months. Notably, the most polluted month in the past 106 months was January 2023, with an AQI of 281, while the least polluted month was July 2021, with an average AQI of 76.

Reckless human activities have turned air pollution into a global crisis. The vehicles we rely on for daily commutes burn fossil fuels, releasing carbon monoxide and fine particulates. Factories and power plants emit large amounts of sulfur dioxide, nitrogen oxides, and particulate matter. In Bangladesh, nearly 7,000 traditional brick kilns emit massive amounts of toxic smoke, making them one of the biggest contributors to air pollution. Dust from construction sites and the open burning of waste exacerbate air pollution, especially in the urban areas. Methane emissions from livestock and ammonia from fertilisers add to the problem.

Air pollution is also a major cause of asthma, bronchitis, and chronic obstructive pulmonary disease (COPD). Prolonged exposure increases the risk of heart attacks and strokes. Particulate matter and other pollutants are known carcinogens, which cause different types of diseases. Because of air pollution, children are suffering from stunted lung development and the elderly are facing aggravated health issues. A recent study by the Health Effects Institute revealed that air pollution was responsible for approximately 195,000 deaths in Bangladesh in 2022 alone. Sulphur dioxide and nitrogen oxides are kinds of pollutants that combine with water vapour, and damage crops, forests, and aquatic ecosystems. Greenhouse gases are also significant components of air pollution and are accelerating climate change.

The World Bank estimates that air pollution costs the global economy $8.1 trillion annually, equivalent to 6.1% of global GDP. In Bangladesh, healthcare costs and lost productivity due to pollution are staggering. Air pollution in Dhaka city has significant implications for urban temperature increase.

Nevertheless, the aerosol effects, heat absorption, urban heat island effect, reduction of vegetation and green spaces, altered atmospheric conditions, and changes in atmospheric stability all contribute to the rise in urban temperatures. The consequences of increased urban temperatures include compromised human health, reduced energy efficiency, and a less comfortable living environment.   

Governments need to enforce emission standards for vehicles and industries. Strengthening institutions to monitor air quality and penalise violators is crucial. Meanwhile, educating people about the dangers of air pollution and how they can reduce their carbon footprint is the key. Air pollution knows no borders, so forging global collaboration is essential. Agreements like the Paris Accord and regional initiatives can help countries share technologies, strategies, and financial resources to combat pollution.

Every breath we take carries a mix of life-sustaining oxygen and dangerous pollutants. But we have a choice. By making conscious decisions, demanding action from our leaders, and investing in sustainable solutions, we can clear the air for ourselves and future generations.
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The writer is Professor and Dean, Faculty of Science, Stamford University, and Joint Secretary, Bangladesh Poribesh Andolon (BAPA)