Infiltration of diesel exhaust from a loading dock into a nearby building

Abstract

A loading dock is a common functional component of modern commercial and institutional buildings where substantial amount of air pollutants might be emitted by diesel trucks. This study aims to determine whether pollutants in a loading dock could infiltrate into nearby indoor environments through mechanic ventilation systems. We measured the levels of fine particulate matter (PM2.5) and black carbon (BC), and particle size distributions at a loading dock and inside three offices of a nearby building. We observed increased levels of PM2.5 and BC both at the loading dock and in the offices due to trucking activities. The infiltration factors (Fin), defined as the equilibrium fraction of outdoor particles that penetrates indoors, were greater for BC (range: 0.20–0.24) as compared with PM2.5 (range: 0.02–0.13) and were greater for larger particles in the size range of 7.64–289 nm. To reduce human exposures to those particles, an anti-idling policy was implemented at the loading dock as part of the study. As a result, the levels of PM2.5 and BC were significantly (p < 0.001) decreased at the loading dock, but the BC levels were increased in the offices due to elevated infiltration factors after the intervention. Our findings suggest that the location of building air intake, truck activities at the loading dock, and particle's infiltration rate are important factors affecting the indoor air quality of the nearby building.