Abstract
This study investigates the impact of the third phase of the odd–even vehicle scheme on particulate matter (PM) concentrations at four traffic intersections in Delhi: Pitampura, Panchkuian Road, Najafgarh Road, and DTU Road. Parameters include PM10, PM2.5, PM1, and fine particles (inhalable, thoracic, and alveolar). Significant reductions in PM concentrations were observed, particularly on odd days. At Pitampura, for example, the maximum PM10 concentration recorded was 446 µg/m³ on a normal day, which reduced to 168 µg/m³ on an odd day (p < 0.05). The study reveals spatial variability in PM reduction, with more substantial decreases in city center locations. For instance, PM10 levels in Panchkuian Road reduced from 328.8 µg/m³ on a normal day to 262.6 µg/m³ on an odd day (p < 0.01). Meteorological parameters remained consistent, confirming that observed reductions were primarily due to the odd–even scheme. These findings underscore the scheme’s effectiveness in improving air quality, particularly in areas with high vehicular traffic, demonstrating a 41–49% reduction on odd days and 18–48% on even days for different PM sizes. This study highlights the need for targeted policies to address vehicular emissions and provides evidence supporting the odd–even scheme as a viable strategy for air quality improvement in urban environments.