ABSTRACT A comprehensive investigation of airborne particulate matter (PM 2.5 and PM 10 ) mass concentrations and PM 2.5 /PM 10 ratio characteristics over South India was conducted using 5 years (2019–2023) of regulatory data. Population‐based tiers were used to assess heterogeneity in PM levels across the tiers. While PM exhibited the well‐understood seasonal and diurnal patterns, there was no significant difference in the PM distributions across Tier 1 (cities with population above 5 million; study period mean PM 2.5 PM 10 : 36 ± 22 72 ± 39 µg m −3 ) and Tier 2 (cities with population between 0.5 and 5 million; study period mean PM 2.5 PM 10 : 36 ± 24 79 ± 51 µg m −3 ) cities. The city‐wise analysis revealed that no clear PM pattern linked to tier classification. Tier 3 (cities with population below 0.5 million) cities were found to be marginally cleaner overall (study period mean PM 2.5 PM 10 : 31 ± 22 62 ± 37 µg m −3 ), while their ratio was the highest (∼ 0.5), indicating anthropogenic source dominance. Correlation analysis suggests that (i) similar sources contribute to both PM size fractions (with stronger similarity in Tier 3 cities), (ii) lesser meteorological impact on the observed daily mean PM, and (iii) a strong regional PM influence on the observed concentrations at city level. The deseasonalized PM data showed weak annual trends (ranging between −1.6 and 0.4 µg m −3 year −1 ).
Vellaturi et al. (2026) studied this question.