Emissions from the brick manufacturing industry

Abstract

Brick manufacturing is the fastest-growing industrial sector in Bangladesh and among the major contributors to the air pollution and health problems in Dhaka, along with vehicle exhaust, resuspended road dust, and domestic fuel burning. There are about 1,000 brick kilns in Dhaka region from the districts of Dhaka, Gazipur, Manikganj, and Narayanganj. Brick manufacturing is confined to the non-monsoonal months and produces 3.5 billion bricks per year, using energy-inefficient fixed-chimney Bull trench kiln technology fuelled with coal and agricultural waste. The total annual emissions are estimated as 23,300 tons of PM2.5, 15,500 tons of SO2, 302,000 tons of CO, 6,000 tons of black carbon, and 1.8 million tons of CO2. The associated health impacts largely fall on the densely populated districts of Dhaka, Gazipur, and Narayanganj. Using the ATMoS dispersion model, the impact of brick kiln emissions was estimated over Dhaka region - ranging from 7 to 99 µg/m3 (5th and 95th percentile concentration per model grid) at an average of 38 µg/m3 - and provincial cluster contributions of 27 % originating from Narayanganj (to the south with the highest kiln density), 30 % from Gazipur (to the north with equally large cluster spread along the river and canals), and 23 % from Savar of Dhaka district. The modelling results were validated using evidence from receptor modelling studies conducted in Dhaka region. An introduction of emerging vertical shaft combustion technology and a possible relocation of the northern clusters to the southeast can provide faster benefits for public health and reduce climate precursor emissions.