A blanket of dust: Why Dhaka suffocates every winter
To its 23 million residents, this is not just air; it’s a toxic cocktail of pollutants that invades every breath
Every winter, Dhaka transforms.
The cool, crisp mornings should bring respite from the relentless summer heat.
Instead, the city is wrapped in an unwelcome blanket – thick, choking, and laced with invisible dangers.
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To its 23 million residents, this is not just air; it's a toxic cocktail of pollutants that invades every breath.
While Dhaka's air quality is abysmal year-round, winter is when the crisis peaks.
The reason lies in a deadly combination of environmental and human-made factors.
During winter, a meteorological phenomenon known as "temperature inversion" traps pollutants closer to the ground.
Typically, warm air rises, taking pollutants with it. But in winter, a layer of cool air gets trapped under a layer of warm air, effectively sealing pollutants in.
This inversion coincides with increased construction activity.
Dhaka's relentless urbanisation sees countless construction sites kicking up dust — one of the primary contributors to its polluted air. The fine particulate matter (PM2.5) from this dust not only taints the skyline but also penetrates deep into the lungs, causing respiratory and cardiovascular problems.
Adding to the mix are brick kilns, which operate in full swing during the dry winter months. These kilns, often outdated and highly polluting, are scattered around Dhaka's outskirts. They release a significant amount of carbon monoxide, sulfur dioxide, and particulate matter into the atmosphere, worsening the city's air quality.
Another culprit is road dust, which is omnipresent in Dhaka.
With dry weather and insufficient rainfall to wash it away, the dust accumulates. Heavy traffic and poorly maintained roads churn it into the air, where it lingers, mixing with emissions from vehicles running on low-quality fuel.
Particles like PM2.5 and PM10 are so fine that they can penetrate the bloodstream.
This exposure can lead to chronic damage to vital organs, including the lungs, heart, and brain.
For children and the elderly, the risks are particularly acute. A 2022 study revealed that air pollution leads to an increase in asthma attacks, chronic obstructive pulmonary diseases (COPD), and even neurological issues. Long-term exposure has been linked to a rise in cancer cases and premature deaths in the city.
Interestingly, not all of Dhaka's pollution is homegrown. Experts point to "transboundary air pollution" as another factor.
During winter, wind patterns bring pollutants from neighbouring regions, including India, where crop residue burning contributes to high levels of particulate matter. This external pollution adds to Dhaka's already grim situation.
Experts agree that tackling Dhaka's winter air pollution requires a multi-pronged approach. Better regulation of construction sites and mandatory dust management measures could significantly reduce airborne particulates. Upgrading the technology used in brick kilns and switching to cleaner energy sources are crucial steps.
Additionally, addressing transboundary air regional cooperation, including agreements with neighbouring countries to curb crop burning during winter.
A city at crossroads
Air quality in Dhaka from November to February has consistently been hazardous over the past nine years, according to the Center for Atmospheric Pollution Studies (CAPS).
Recent data showed Dhaka ranked among the world's most polluted cities, with AQI scores of 234 and 160 on consecutive days.
Even today (5 December) Dhaka has again topped the list of cities around the world with the worst air quality with an air quality index (AQI) score of 392 at 9am.
Analysis reveals January is typically the worst month for air quality, with an average AQI of 250 over nine years.
Notably, January 2023 recorded an average AQI of 281, the worst in 106 months. By contrast, July 2021 had the cleanest air, with an AQI of 76. Annual averages also show a worsening trend, with AQIs of 159 in 2021, 160 in 2022, and 171 in 2023.
For now, Dhaka remains a city at the mercy of its own growth and the whims of winter weather. As the season deepens, the air thickens, and millions brace themselves for months of discomfort. But beneath the dust lies a sobering truth– without drastic measures, the city's air will only grow deadlier with each passing year.
It's not just the air that's at stake— it's the future of a city struggling to breathe.
