Model calculations of long term average concentrations of SO2, NOx and SPM in Delhi.

NILU has in collaboration with CPCB in Delhi carried out the first estimates of long term averaged ground level concentrations of SO2, NOx and SPM in Delhi, India. Based on limited information of emissions, these estimates agreed well with observations for SO2. The winter averaged concentrations of NOx was above the measured NO2-concentrations which indicates that ozone in the limiting factor regarding the formation of NO2. The estimated SPM-concentrations was too low compared to measurements in Delhi. More detailed information of emissions and consumption of fossil fuels and improved emission factors for traffic and coal consumption might improve the modelling results.