Screening for Indoor air Quality of Air-Conditioned Offices

Abstract

It would be costly to sample all toxic air pollutants to which an entire community is exposed. In Hong Kong, a voluntary Indoor Air Quality (IAQ) certification scheme for IAQ assessment in workplaces proposes the measurement of the levels of 12 parameters: carbon dioxide, carbon monoxide, respirable suspended particulates, nitrogen dioxide, ozone, formaldehyde, total volatile organic compounds, radon, airborne bacteria count, temperature, relative humidity and air velocity. This study investigates the feasibility of a screening process for presumptive detection of unrecognised IAQ problems in an indoor environment. From the full IAQ assessment results of 422 air-conditioned offices in Hong Kong, three of nine listed common air pollutants are selected as ``representative'' pollutants for an overall ``satisfactory IAQ''. In particular, an ``IAQ index'' using the average fractional dose corresponding to given exposure limits of the representative pollutants as a simple screening test for asymptomatic IAQ problems in air-conditioned offices is proposed. The index was evaluated in terms of test sensitivity, specificity and predictive value. Such a screening test would be a useful tool for policymakers, building owners and professionals to identify offices with probable IAQ problems. Making better decisions regarding resources for an IAQ surveillance programme could help to ensure a healthy and safe workplace.