Satellite or ground-based measurements for air pollutants (PM_2.5, PM₁₀, SO₂, NO₂, O₃) data and their health hazards: which is most accurate and why?

Air pollution is growing at alarming rates on regional and global levels, with significant consequences for human health, ecosystems, and change in climatic conditions. The present 12 weeks (4 October 2021, to 26 December 2021) study revealed the different ambient air quality parameters, i.e., PM_2.5, PM₁₀, SO₂, NO₂, and O₃ over four different sampling stations of Delhi-NCR region (Dwarka, Knowledge park III, Sector 125, and Vivek Vihar), India, by using satellite remote sensing data (MERRA-2, OMI, and Aura Satellite) and different ground-based instruments. The ground-based observation revealed the mean concentration of PM_2.5 in Dwarka, Knowledge park III, Sector 125, and Vivek Vihar as 279 µg m^-3, 274 µg m^-3, 294 µg m^-3, and 365 µg m^-3, respectively. The ground-based instrumental concentration of PM_2.5 was greater than that of satellite observations, while as for SO₂ and NO₂, the mean concentration of satellite-based monitoring was higher as compared to other contaminants. Negative and positive correlations were observed among particulate matter, trace gases, and various meteorological parameters. The wind direction proved to be one of the prominent parameter to alter the variation of these pollutants. The current study provides a perception into an observable behavior of particulate matter, trace gases, their variation with meteorological parameters, their health hazards, and the gap between the measurements of satellite remote sensing and ground-based measurements.