Dhaka Air Quality (AQI)

Dhaka's extreme pollution stems from a combination of geography, industry, and density. The Indo-Gangetic Plain geography creates temperature inversions in winter — cold dense air traps warm polluted air near the surface for days. Surrounding the city are approximately 1,000 brick kilns within 30 km that burn coal and biomass from October through April to produce the bricks for Dhaka's massive construction boom. A vehicle fleet of over 1.2 million registered vehicles — including millions of two-stroke three-wheelers with no catalytic converters — adds continuous PM2.5 and NO2. Industrial zones in Tongi, Gazipur, and Narsingdi add heavy metals and fine particles. Finally, at 44,000 people per km², Dhaka is the world's most densely populated large city, meaning all emission sources are packed into an impossibly small area.

The monsoon months — June through September — are Dhaka's air quality respite. Heavy rain washes PM2.5 from the atmosphere, and the southwest monsoon winds bring cleaner oceanic air from the Bay of Bengal. July is typically the cleanest month, with AQI values often below 60 (Moderate). The worst period is November through February, when brick kilns operate at full capacity, winter inversions trap emissions, and the city can see AQI readings of 300–400+ (Hazardous). March and April are intermediate — kilns slow but pre-monsoon heat creates its own ozone and dust issues.

Bangladesh's construction boom demands over 25 billion bricks per year, produced by approximately 8,000 brick kilns scattered around Dhaka and other cities. Traditional Fixed Chimney Bull's Trench Kilns (FCBTK) burn coal and biomass inefficiently, emitting PM2.5, PM10, SO₂, CO, and black carbon. The kilns operate seasonally — October to April during the dry season — precisely the period of worst natural dispersion conditions. Studies have found brick kilns contribute 15–30% of Dhaka's winter PM2.5. Bangladesh has programs to promote cleaner Hybrid Hoffman Kiln (HHK) and Zigzag kiln designs that reduce emissions by 30–60%, but adoption is slow due to capital costs and lack of enforcement.

Industrial and transport hubs have the worst air quality. Tongi and Gazipur in north Dhaka border industrial zones with textiles, garments, pharmaceuticals, and manufacturing. Hazaribagh in west Dhaka was home to one of the world's largest tannery clusters (now partially relocated to Savar) and still suffers residual chromium and leather dust contamination. The Buriganga riverfront in old Dhaka gets emissions from thousands of motor launches and ferries. Mirpur and Mohammadpur see heavy traffic-related pollution. Even nominally 'better' areas like Gulshan and Banani experience AQI 200+ on winter mornings. There is no truly clean neighborhood in Dhaka during winter.

Dhaka, Delhi, and Beijing are all severely polluted megacities, but with different profiles. Delhi PM2.5 ≈ 92 μg/m³ annual average, Dhaka ≈ 73 μg/m³, Beijing ≈ 35 μg/m³ (down dramatically from 85+ in 2013). Beijing has made the most progress through its Clean Air Action Plan. Delhi's worst days (crop burning + winter inversions) can exceed Dhaka's, but Dhaka's sustained annual average is severe. A key difference: Beijing and Delhi have international monitoring networks and published real-time data; Dhaka's monitoring infrastructure is much thinner, so its true average may be understated. IQAir's 2024 World Air Quality Report ranked Bangladesh as the world's 3rd most polluted country.