An Assessment of Two-Wheeler CO and PM Exposures Along Arterial Main Roads in Bangalore City, India

ABSTRACT

This study investigated 2-wheeler exposures to CO and PM₁₀ along six standardized arterial main road stretches in Bangalore city in India during morning peak (9:00-11:00) and afternoon non-peak hours (13:00-15:00) using personal samplers. Background levels on a local street carrying no traffic and away from main roads were also monitored to determine the actual contributions of vehicular traffic to exposure. Road stretches were selected to compare exposures on two types of routes - inner arterials and outer arterials with different built form characteristics.

Results indicate that average background PM₁₀ and CO concentrations were much lower than the respective averages of the 2-wheeler exposures as expected. While PM₁₀ exposures for inner arterials were higher than for outer arterials (p=0.007), differences were much larger for CO (p<0.001). Since the average run speeds were comparable for the stretches, the variations in PM₁₀ and CO could be attributed to different vehicular compositions and built form characteristics of the stretches, but this needs to be verified through further investigation. PM₁₀ exposures during nonpeaks were lower than during morning peaks (p=0.02). However, CO exposures were not very different between non-peak hours and morning peak hours (p=0.138) despite comparable average run speeds and shows that even lower traffic volumes during non-peak hours result in high exposures. Results of various bivariate models indicate that average run speed is a good predictor of CO exposures (R²=0.56) but is only a minor predictor of PM₁₀ exposures (R²=0.18) in Bangalore.

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