Passive Sampling of Ambient Nitrogen Dioxide at Toll Plazas in Malaysia

Abstract

With the increasing trend of development and industrialization in Malaysia, air pollution has become an inevitable part of the process, resulting from increased vehicular activities and industrial processes. Toll operators are potentially exposed to high levels of air pollutants from working in proximity to traffic pollution sources, thereby increasing their risk of health defects associated with air pollution exposure. This study assessed the levels of Nitrogen dioxide (NO 2 ) toll operators are exposed to, considering the influences traffic density and meteorological factors. This is intended to serve as an indicator of the cumulative pollution emanating from the combustion process of vehicles at toll plazas. Using Passive diffusion samplers saturated with Triethanolamine (TEA), the weekly indoor and outdoor NO 2 concentrations at tollbooth were measured at Sungai Besi (SB), Kajang (KJ) and Putra-Makhota (PM) toll Plazas, to capture the varying traffic densities of 138,000, 65,000 and 24,100 vehicles/day respectively. The results showed that NO 2 concentrations increase with traffic densities, and indoor NO 2 concentrations correlated highly with outdoor NO 2 concentrations (R 2 : SB = 0.767, KJ = 0.689 and PM = 0.877). The indoor/outdoor NO 2 ratio varied from 0.7 to 1.2 for all toll booths, suggesting pollution control in-efficiency, caused by technical and behavioural factors. Also, meteorological factors had no significant effect on nitrogen dioxide concentrations, contrary to previous studies, which is likely due to the far distance between tool plazas and meteorological stations. Furthermore, the NO 2 concentrations reported in this study were higher in comparison to weekly standards adopted in Germany (0.032 ppm) and previous literature. Therefore, toll operators are potentially exposed to high levels of pollution, and we advise that toll operators to wear pollution protection gears to reduce the risk of exposure, and the ventilation systems and mitigation measure (air curtain) reviewed to assess its efficiency.

Human Health Risks and Interference of Urban Landscape and Meteorological Parameters in the Distribution of Pollutant: A Case Study of Nakhon Si Thammarat Province, Thailand

“…The number of vehicles is a direct factor as an emission source affecting near-road NO 2 concentrations in urban areas, which are significantly related to traffic density [1,15]. Previously, meteorological factors including temperature, humidity, wind speed, and rainfall were reported to be related to the concentration of NO 2 in the studied areas [16,17]. Some factors, such as temperature and humidity, present both positive and negative effects on NO 2 concentrations in different areas because the anthropogenic landscape and microclimate changes have a significant impact on NO 2 concentrations in urban areas [17].…”