Exposure to inhalable aerosols and their chemical characteristics from different potential factors in urban office environments

Abstract

Indoor air quality (IAQ) is one of important issues in indoor environment due to exposure to inhalable aerosol which is affected by indoor and outdoor factors. To demonstrate the effect of indoor and outdoor to the IAQ, this study presents three fractions of particulate matter (PM) (PM_2.5, PM₄, PM₁₀), characterization of I/O ratios for PM under potential indoor (average occupancy) and outdoor factors (Asian dust, rain, wind, and snow days) and evaluation of chemical components in aerosols. In the chemical characteristics of PM, organic carbon (OC), elemental carbon (EC), and trace elements were analyzed in indoors and outdoors. There was no significant difference of respirable aerosol (PM_2.5 and PM₄) concentration in different indoor environments. The concentration of OC in PM₁₀ was lower in indoor than outdoor in summer and winter seasons, while the concentration of OC in PM_2.5 was higher in indoor than outdoor. Also, the OC/EC ratios in PM_2.5 were higher than those in PM₁₀. Further, the ratios of trace elements in PM_2.5 and PM₁₀ were different at various locations within the building. This study demonstrated that the exposure to PM_2.5 is greatly affected by outdoor environment. Although there was no difference in inhalable and respirable aerosol concentration at different locations within the building, the impact of outdoor factors is strongly supported by OC/EC ratios and PM_2.5/PM₁₀ ratios of trace elements. This study shows that chemical components through the HVAC system affected the exposure to the indoor respirable aerosol, which could lead to adverse effect on the indoor air quality.

Keywords: Carbonaceous aerosol; Exposure to indoor PM; HVAC system; Inhalable aerosol; Respirable aerosol; Trace element.