Personal exposure to particulate matter in various modes of transport in Kathmandu, Nepal

Abstract

BACKGROUND AND AIM: Particulate matter pollution concentration in Kathmandu valley exceeded up to 9 fold higher than the World Health Organization 24 hour guidelines. Daily commuting to work in a vehicle increases particulate matter exposure and it is influenced by mode and time of commuting. This study aims to investigate the effect of commuting in various modes of transportation on personal exposure to particulate matter with aerodynamic diameter ≤ 2.5 µm (PM2.5). METHODS: Real-time personal exposure to PM2.5 was monitored in four different modes of transportation: personal bike, private cars, public cars (taxi) and bicycle. The exposure was monitored for each transport mode in three different road stretches of Kathmandu twice a day for peak hours and off-peak hours. The measurements were repeated for each transport mode for 10 measurement days in all three routes. RESULTS:The result showed that peak hour average concentration of PM2.5 for all mode of transport was higher than the average concentration during off peak hour in all three routes. There was a variation in average concentrations in all transport mode, and the commuters travelling through bicycle were exposed to highest average PM2.5 (205 ug/m3) in all road stretches during peak hours. However, off peak hours average concentration was lowest for cyclists(86 ug/m3) as compared to other transport modes. The commuters travelling through bike (193 ug/m3), taxi (155 ug/m3) and car (150 ug/m3) were exposed to respective decreasing peak hour average concentrations of PM2.5. CONCLUSIONS:This study showed the effect of commuting on different modes of transport during peak and off peak hour on personal exposure to particulate matter. The result of this study hence helps commuters to choose appropriate travel arrangements to minimize exposure to ambient air particulates. KEYWORDS: Personal exposure, Particulate matter, PM2.5, Mode of transport