Comparative study of gaseous pollutants and particulate matter for major cities in the foothills of Garhwal Himalaya of Uttarakhand

In the present paper, the variability of gaseous pollutants (SO2 and NO2) and particulate matter (PM10) at three major cities (viz., Dehradun, Rishikesh, and Haridwar) in the Garhwal Himalaya in Uttarakhand are investigated. The decadal behavior of gaseous pollutants and particulate matter (2011-2020) was studied by utilizing data from five different recording stations established by the Uttarakhand Pollution Control Board. A detailed statistical analysis of the monthly and annual variability of SO2, NO2, and PM10 along with the meteorological parameters is performed. At five different places, CT (Clock Tower), RR (Raipur Road), ISBT (Inter-State Bus Terminal), NPP (Nagar Palika Parishad), and SIDCUL (State Industrial Development Corporation of Uttarakhand Limited), the lowest monthly concentrations of SO2 and NO2 were 7.42, 6.73, 9.16, 5.98, and 3.03 g/m(3) and 8.93, 7.87, 11.63, 7.62, and 8.68 mu g/m(3), respectively. The PM10 concentration was found to vary between 73.51-310.73 mu g/m(3), 67.95-483.18 mu g/m(3), 70.91-388.67 mu g/m(3), 33.98-195.71 mu g/m(3) and 46.08-220.64 mu g/m(3)at CT, RR, ISBT, NPP, and SIDCUL respectively. The seasonal and annual variability of SO2, NO2 and PM10 were also analyzed, and it was found that the concentration of gaseous pollutants and particulate matter was relatively lower during the monsoon season (except for the year 2020). The annual mean concentration of gaseous pollutants SO2 and NO2 was under the prescribed limit of the NAAQS (National Ambient Air Quality Standards) fixed by the CPCB (Central Pollution Control Board), but the NO2 concentration was higher than the guideline values of the WHO (World Health Organization). The annual mean concentration of PM10 was much higher than the NAAQS by CPCB and the permissible limit given by WHO. The variability of meteorological parameters during the study period was also analyzed. A very strong positive correlation has been observed between the gaseous pollutants SO2 and NO2 (0.88, 0.93, and 0.94 in CT, RR, and ISBT respectively) and PM(10)havea strong correlation with SO2 (0.62) and NO2 (0.64) in the ISBT site. The linear regression plots between gaseous pollutants (SO2 and NO2) and particulate matter (PM10) have been shown at all study sites. The present detailed analysis of air pollutants along with the meteorological parameters might be helpful for policy-making related to air quality control in this region.