Estimation of background concentration of ambient pollutants for Delhi NCT region

Abstract

The increased levels of ambient air pollution in Delhi are hazardous to human health and a matter of concern for policymakers. To develop effective regulatory policies, it is necessary to gain a better understanding of the regional background concentrations of pollutants. In the present study, we proposed a method to estimate regional background concentration for the Delhi NCT region. The study uses an integrated approach that employs meteorological filtering and statistical techniques. The meteorological filtering factored in the phenomena of stagnation caused by low wind speed and temperature inversion. Whereas spectral analysis and the Kolmogorov-Zurbenko (KZ) filter were used in combination to reduce the influence of synoptic fluctuation in the time series. Our estimated annual average background concentration for PM10, PM2.5, NO₂, SO₂ and CO are 56 μg/m³, 42 μg/m³, 18 μg/m³, 7 μg/m³ and 558 μg/m³ respectively. The estimated background concentrations were validated using the ambient pollutant concentration recorded during the 2020 Covid-19 lockdown period.