Studies on the variation in concentrations of respirable suspended particulate matter (PM10), NO2 and SO2 in and around Nagpur

Abstract

The objective of this study is to assess the long-term variation in concentrations of Respirable suspended particulate matter (PM₁₀), sulphur dioxide (SO₂) and nitrogen dioxide (NO₂) in the ambient air of Nagpur (India) during 2011-2018. The pollution data during the above period at three locations, viz., residential (Station-I), industrial (Station-II), and commercial location (Station-III) has been analyzed. The highest daily average concentration of PM₁₀ at residential, industrial, and commercial locations was found 154 microgm/m³, 199 microgm/m³, and 153 microgm/m³, whereas, the average annual concentration at these locations was found 101.87 microgm/m³, 115.37 microgm/m³ and 98.75 microgm/m³, respectively during the above period. The highest daily average concentration of SO₂ was found at 18 microgm/m³, 22 microgm/m³ and 19 microgm/m³ and the average annual concentration was 13.25 microgm/m³, 13.5 microgm/m³, 13 microgm/m³ at respective locations. And the highest daily average concentration of NO₂ was found 77 microgm/m³, 60 microgm/m³, 60 microgm/m³ and the annual average concentration was 44.125 microgm/m³, 41.825 microgm/m³ and 40.25 microgm/m³ at the respective locations. The exceedance factors for PM₁₀ varied from 'moderate to high' at the residential and commercial locations and from 'high to moderate' at the industrial location. Planetary boundary layer height (PBLH) and ventilation coefficient (VC) were also estimated over the region for 2011-2018. The maximum PBLH and VC observed during the study period was in the summer season, and the minimum was in the post-monsoon season. Annual and Seasonal Air quality index analysis shows that the level of pollution was in the range of SATIFACTORY to MODERATE. A study of seasonal analysis of PM₁₀, SO₂ and NO₂ showed that the higher concentrations were found in winter relative to summer with the least concentration occurring during the monsoon season. A regression analysis was performed to check PM10's interdependence with other contaminants. A positive association was found between PM₁₀ and SO₂ for all seasons. A negative association was found between PM₁₀ and NO₂ in summer for all the stations and winter at Station-I and Station-III. Similarly, the correlation between PM₁₀ and meteorological parameters such as wind speed and temperature was found to be negative whereas it was positive for relative humidity.