Seasonal and Diurnal Patterns of Air Pollutants in Faridabad: A 2024 Urban Air Quality Assessment

Air pollution poses a severe threat to public health in Indian cities such as Faridabad, where vehicular traffic, industrial activities, and seasonal biomass burning intensify pollutant concentrations. This study aims to analyze hourly air quality data from 2024 to examine the diurnal and seasonal variations in six major pollutants and their compliance with air quality standards. The results revealed that the PM2.5 concentration peaked at 171.85 µg/m³ in winter, exceeding the WHO 24-hour limit of 15 µg/m³ by more than 11 times, whereas the PM10 concentration reached 271.48 µg/m³. Ozone concentrations peaked at 69.48 µg/m³ in summer afternoons, crossing the WHO 8-hour average guideline of 60 µg/m³. Diurnal patterns showed morning and evening peaks for PM2.5, NOx, and CO due to traffic emissions and stable atmospheric conditions, whereas ozone displayed a strong afternoon peak due to photochemical formation. Correlation analysis revealed strong associations among PM2.5, PM10, NOx, and CO (r > 0.85), whereas ozone was negatively correlated with NOx in summer (r = –0.63), confirming NOx titration. The PM2.5/PM10 ratio ranged from 0.52 to 0.63 across seasons, indicating a dominant contribution from fine particulates linked to combustion sources. These findings underscore the need for season- and time-specific interventions, including stricter emission standards, VOC controls, real-time air quality alerts, and coordinated action on crop residue burning to reduce health risks in urban India.