Effect of ventilation settings on the in-car PM concentrations and the associated health risks in Kanpur, India

Abstract

This study examines the seasonal variations in air quality within a car cabin under four different ventilation settings: (1) windows open (WO), (2) windows closed with air conditioning on and recirculation enabled (AC RC on), (3) windows closed with air conditioning on but recirculation disabled (AC RC off), and (4) windows closed with the fan off (Fan off). Additionally, the associated health risks were calculated using the ICRP method. A total of 120 trips were conducted on two different routes across two seasons (winter and summer) to monitor PM_2.5 (fine particulate matter <2.5 μm) and PM₁₀ (coarse particulate matter <10 μm) concentrations. A portable laser air quality sampler was used to measure PM concentrations and identify factors influencing air quality within the car cabin. The results indicate that the WO setting had the highest PM_2.5 concentration (197.6 μg/m³) and deposition dose (1.53 μg/min), followed by the AC RC off setting (124.9 μg/m³, 1.04 μg/min), the Fan off setting (114.4 μg/m³, 0.88 μg/min), and the AC RC on setting (87.4 μg/m³, 0.69 μg/min). PM concentrations in winter were observed to be three to four times higher than in summer under all ventilation settings. Key factors influencing exposure levels include ventilation rates, traffic conditions, meteorological parameters, and surrounding environments. The dominance of PM suggests that conventional car filters are ineffective in removing them, thereby need for improved filtration systems. These findings provide valuable insights for commuters making informed ventilation choices and policymakers for developing strategies to improve in-car air quality.