Seasonal Variation of Particulate Matter (PM2.5 and PM10) in Delhi

Abstract– This study investigates the seasonal variability of particulate matter (PM_2.5 and PM₁₀) concentrations across three distinct sites in Delhi in the year 2024—Rohini (residential), Karol Bagh (heavy-traffic), and Wazirpur (industrial)—to assess the influence of meteorological conditions and localized emission sources. Results revealed a consistent seasonal trend of Winter > Post-Monsoon > Summer > Monsoon across both PM_2.5 and PM₁₀. The highest concentrations were observed in winter, with Rohini peaking at 211.14 µg/m³ (PM_2.5) and 314.27 µg/m³ (PM₁₀), indicating strong accumulation under low temperature and high humidity. In Karol Bagh, maximum winter values reached 158.72 µg/m³ (PM_2.5) and 275.58 µg/m³ (PM₁₀), while Wazirpur recorded 173.51 µg/m³ (PM_2.5) and 250.54 µg/m³ (PM₁₀). The pronounced winter peak can be attributed to temperature inversions, lower boundary layer height, and increased biomass burning, all of which restrict vertical mixing and trap pollutants near the surface. In contrast, higher temperatures and stronger winds in summer enhanced atmospheric dispersion, while monsoonal rainfall facilitated wet scavenging, thereby reducing particulate load. Seasonal minima were observed during the monsoon, with the lowest PM _2.5 at Karol Bagh (58.06 µg/m³) and the lowest PM₁₀ at Karol Bagh (95.05 µg/m³), reflecting effective wet deposition. Wazirpur, however, maintained comparatively elevated monsoon levels (110.22 µg/m³ PM_2.5; 198.45 µg/m³ PM₁₀), suggesting persistent industrial emissions. Post-monsoon concentrations again increased, particularly at Rohini (160.57 µg/m³ PM _2.5) and Wazirpur (199.59 µg/m³ PM₁₀), consistent with regional biomass burning and reduced rainfall. This study demonstrates how temporal and spatial analysis of air quality data, supported by statistical techniques, is critical for formulating targeted, evidence-based policies that align with sustainable development goals and safeguard public health in megacities like Delhi.

Key words: Air Pollution, Particulate Matter, PM_2.5, PM₁₀, Seasonal Variations, Delhi