Spatiotemporal variability and source attribution of PM2.5/PM10 ratios: Aerosol type classification and AQI evaluation across seventy monitoring stations in Delhi and Haryana, India

Abstract

The present study examines PM2.5 and PM10 levels at 70 CAAQMS stations across Delhi and Haryana from 2020 to 2023. The aerosol-type classifications were employed based on PM2.5/PM10 ratios, revealing a significant source of particulate matter. PM2.5 levels increased from 84.31 μg/m³ in 2020 to 154.64 μg/m³ in 2023, while PM10 rose from 171.12 μg/m³ to 268.46 μg/m³, both exceeding NAAQS limits and posing risks to human health and the environment. The lower concentration in 2020 was linked to reduced activities during the COVID-19 lockdowns. Chandni Chowk had the highest PM2.5 levels in 2020, but by 2023, New Moti Bagh had become the most polluted. For PM10, Chandni Chowk recorded the highest concentration in 2020 and 2021, while Anand Vihar surpassed it in 2022 and 2023. Seasonal variation showed higher PM2.5/PM10 ratios in winter and post-monsoon, and lower ratios in the monsoon and pre-monsoon seasons due to climatic factors. Delhi has higher PM2.5/PM10 ratios than Haryana, likely due to greater vehicular density and industrial activity. PM2.5/PM10 ratio analysis reveals that mixed-anthropogenic type (IIb1) and mixed dust type (IIb2) dominate the aerosols in Delhi and Haryana. The AQI results reveal that PM2.5 is the dominant pollutant in Delhi and Haryana across all seasons (2020–2023), with the highest values during winter, 220 and 179 days and in post-monsoon, 280 and 302 days, respectively. The study emphasises the need for stricter emission controls, particularly in Delhi, and aligns with SDG 11, supporting urgent policies to combat air pollution and protect community health and the environment.