Kolkata: An updated ‘air pollution source apportionment and atmospheric carrying capacity study’ in Kolkata Municipal Corporation (KMC) areas to assess the air pollution impact management (AQM) activities has identified non-energy sources (road dust resuspension, construction dust, refuse burning, landfill-fire and cremation activity) as the major source of atmospheric PM 10 (83 per cent) and PM 2.5 (61 per cent).
Vehicle emissions are the major source of most air pollutants. Kolkata, along with five other cities from Bengal, are listed in the catalogue of non-attainment cities together with another 124 cities across India under the NCAP (National Clean Air Programme) based on atmospheric PM10 concentrations in five consecutive years. The Centre launched NCAP in 2019 with an interim target of 40 per cent reduction in atmospheric PM10 in the non-attainment cities by 2026.
In 2022, the West Bengal Pollution Control Board (WBPCB) commissioned The Energy and Resources Institute (TERI), New Delhi to conduct an updated air pollution study within the KMC area to assess Ground Level Concentration (GLC) of air pollutants, prepare a gridded inventory of various source pollutants, conduct source apportionment studies, assess atmospheric carrying capacity, and develop roadmap for sectors to reduce PM 10 and PM 2.5 concentrations.
Atmospheric concentrations of selected pollutants were measured at six selected locations (AQM) in the KMC area following NAMP (National Air Quality Monitoring Programme) guidelines during winter (2022-23 and 2023-24) and summer (2023) seasons. Dust was found to be the dominant source of atmospheric PM 10 at all AQM locations with higher share during summer than winter season.
Coal/biomass-based cooking activities, mainly in residential households and eateries, were estimated as the second largest source of annual atmospheric PM10 (18 percent) while it was estimated as the major source of annual atmospheric PM2.5 (29%) based on the CMB (Chemical Mass Balance) modelling estimation at different AQM locations in the KMC area. Vehicular (20%) and industrial (21%) emissions were the second largest source of PM2.5 annually, suggesting that local emissions near the AQM locations were dominated.
Estimated pollutant emissions were higher towards the KMC area’s central region mainly due to higher density of traffic, solid fuel use in residential cooking in the slum areas and comparatively higher silt content in road dust.