Mitigating particulate matter exposure in naturally ventilated buildings during haze episodes

Publication date: 15 January 2018
Source:Building and Environment, Volume 128
Author(s): K.W. Tham, G.K. Parshetti, R. Balasubramanian, C. Sekhar, D.K.W. Cheong
The effectiveness of a low energy fan-filter unit (FFU) in mitigating human exposure to airborne particulate matter (PM) during haze episodes in a naturally ventilated hostel room is presented. The study adopts a case-reference method by conducting a series of field tests in a test room equipped with FFU and in a reference room with no FFU. PM concentrations were monitored simultaneously indoors and outdoors; including mass concentrations of PM10, PM2.5 and PM1 as well as differential number concentrations of particles ranging from 0.35 μm to 12.5 μm. On average the FFU system reduced PM10, PM2.5, and PM1 particle concentrations by 80.9%, 80.4% and 78.5% respectively inside the test room relative to ambient air concentrations on a real-time comparison basis. The use of FFU operating with a MERV 13 filter during haze episodes is also effective in reducing human exposure to PM-bound toxic trace elements (TrElems) in naturally ventilated indoor environments. The majority of the TrElems (As, Be, Cd, Co, Cr, Ni, Pb, Mn, Zn and Cu) were reduced indoors with I/O ratio of much less than 1. Additionally, FFU demonstrates slight alleviation of thermal discomfort compared to the reference room (whose windows and doors were closed to prevent penetration of haze particles) and achieves thermal conditions within the 80%–90% in the adaptive thermal comfort zone described in ASHRAE Standard 55–2013. The improved thermal conditions with FFU is attributable to provision of increased air exchange (ACH of 4.1 h⁻¹) to displace the indoor generated heat and moisture.

Graphical abstract