Dhaka city dwellers trapped in severe urban smog

Dhaka, a city of narrow alleyways and congested streets, remains one of the world's most polluted, leaving its residents trapped in urban smog and struggling to recall the last time they breathed fresh air, as experts warn of rising life-threatening diseases due to alarming pollution levels, reports UNB.
The city's air is choked with black fumes emitted from thousands of private cars, buses, motorcycles, CNG-run auto-rickshaws, and double-decker buses. Besides, ongoing construction projects, brick kilns, and industrial emissions further deteriorate Dhaka's air quality.
Making matters worse, pollutants from neighbouring countries are also mixing with the city's already toxic air.

Experts estimate that about 35 per cent of Bangladesh's air pollution originates from external sources. However, the government has yet to take any meaningful action to curb this transboundary pollution.
A City Suffocating in Smog
Since Bangladesh's independence in 1971, Dhaka has transformed into one of the most densely populated cities in the world. The average speed of vehicles in the capital has plummeted to just 4.5 km per hour-barely faster than walking.
According to the Air Quality Index (AQI), Dhaka consistently ranks among the most polluted cities globally. On Wednesday (19 February) at 9:00 pm, Dhaka topped the list with an AQI score of 209, marking it as "very unhealthy" for residents.
A recent survey by the Centre for Atmospheric Pollution Studies (CAPS) found that air pollution in December was at its highest level in the past nine years. The situation worsened in January, with pollution levels peaking beyond any recorded in the past decade. On several days that month, the AQI surpassed 300, a level categorised as "hazardous."
In 2023, the average concentration of PM2.5 particles in Bangladesh was 16 times higher than the World Health Organization's (WHO) annual air quality guideline.
What is transboundary air
pollution?
Dr Abdus Salam, a professor in the Department of Chemistry at the University of Dhaka, explains that transboundary air pollution refers to pollutants crossing national borders. "Pollution from the Himalayas, as well as parts of India, Pakistan, Nepal, and China, reaches Bangladesh, significantly impacting our air quality," he said.
The phenomenon is particularly pronounced in winter, when pollution from neighbouring countries drifts into Bangladesh. "The finer the particles, the longer they remain airborne and the further they travel," Dr Salam added, drawing on his 25 years of research into air pollution.
He noted that while some pollutants travel from Bangladesh to India during the monsoon season, about 30-35 per cent of the country's total air pollution originates from external sources.
Prof Ainun Nishat, former vice-chancellor of BRAC University, agrees that air movement naturally carries pollution across borders. "No country deliberately sends pollution to another. However, if all nations in the region take coordinated action, the problem can be mitigated," he said.
Dust on the roads is not air
pollution
Contrary to popular belief, road dust does not significantly contribute to air pollution. "Larger dust particles cannot enter the human respiratory system, so they are not the primary health hazard," explained Dr Salam. Instead, air pollution is driven by ultrafine particulate matter (PM2.5), which penetrates deep into the lungs and bloodstream.
He highlighted that old vehicles are major culprits in Dhaka's air pollution crisis. "CNG-powered machines alone generate trillions of ultrafine particles. Additionally, black carbon and brown carbon emissions from outdated private cars and heavy vehicles further degrade air quality," he said.
To address this, Dr Salam stressed the need for stricter regulations on vehicle emissions, phasing out older vehicles, and ensuring the use of cleaner fuel.
Way forward
To combat transboundary air pollution, Bangladesh must engage in diplomatic dialogue with its neighbouring countries, Dr Salam advised. "We should urge them to control their emissions while improving our own policies," he said.
Other measures include enforcing pollution laws, improving urban planning, and ensuring industrial compliance with environmental regulations. "We must mandate cleaner fuels and impose restrictions on high-emission vehicles.