Reduction of Atmospheric PM2.5 Level by Restricting the Idling Operation of Buses in a Busy Station

ABSTRACT

Fine particulate matter (PM_2.5) is found as a harmful object if inhaled by people which is caused enormous health problem. It is found as high level in public facility of bus station where a lot of passengers and workers might expose to PM_2.5 emission from idling diesel engine (buses). This research evaluated the restriction of idling vehicle as a control strategy of PM_2.5 level in bus station by measuring the level of PM_2.5 and chemical properties in both upwind and exposure sites for comparable data. The sampling work took place in weekend/weekday and before/after vehicle-idling-restriction applied. Originally, the exposure site showed 7% higher PM_2.5 level, non-neutralized nitrate content, anthropogenic metal elements, and higher mobile source contribution evaluated by chemical mass balance (CMB8.2) model. After the prohibition of idling operation of heavy-duty diesel vehicles, the PM_2.5 mass concentrations at exposure site were reduced close to the upwind site. Additionally, the nitrate content was reduced from background. Moreover, the contributions of several anthropogenic metals (Zn, Pb, Mn, Cu, Cr, V, Ni, and Ti) in PM_2.5 were reduced, when the crustal element (Na, Mg, Al, K, and Ca) were much increased after restriction. Finally, the mobile contribution was also decreased to only 33.7–34.5%. Consequently, these finding verified the prohibition policy of idling vehicle is going well as a control strategy to manage the PM_2.5 emission and local hotspot in public facility (bus station).