Street level PM2.5 over a major Indian metropolis using low-cost sensors mounted to bicycles: Elevated exposures to livelihood bicyclists

Abstract

PM_2.5 is a major ambient air pollutant which is responsible for global mortality and morbidity. Vehicular emissions are one of the leading sources of air pollution, especially in urban areas of developing countries like India. Bicycling is an emission-free multipurpose mode of transport, encouraged globally to reduce vehicular emissions. However, bicyclists have higher risks of getting affected by air pollution in comparison to other travelling modes. The study was conducted in a metropolitan city of the Eastern IGP to understand the street-level PM₂.₅ in different road types, its relation to vehicular flow dynamics and the effects on cyclists. Highest PM₂.₅ were recorded during the colder seasons and the least in monsoon, yet the concentrations during the monsoon period were quite high with 14 % of trips surpassing the daily NAAQS values. It was found that primary roads having a higher number of vehicles had significantly higher values of PM₂.₅ across all seasons. Similarly, higher values were associated with office hours as well, clearly indicating the role played by the number of vehicles for heightening the PM_2.5 concentrations. Road-width plays a crucial role in hindering PM_2.5 dispersion, especially on narrow tertiary lanes. Constructional activities on roads were further found to escalate PM₂.₅ loads throughout the dry seasons. A survey involving livelihood and recreational cyclists revealed that the former are more prone to air pollution related diseases. Finally, the study represents the amount of risk faced by livelihood-bicyclists in metro cities and highlights the need for framing policies to control street-level air pollution.