Screening for Indoor Air Quality Express Assessment Protocol of Air-conditioned Offices

A successful Indoor Air Quality (IAQ) surveillance plan is essential for healthy and safe workplaces; yet it is costly to sample all air pollutants of the entire community. In Hong Kong, a voluntary IAQ certification scheme for workplaces proposes the acceptable concentration levels of nine common indoor air pollutants, namely carbon dioxide (CO2), carbon monoxide (CO), respirable suspended particulates (RSP), nitrogen dioxide (NO2), ozone (O3), formaldehyde (HCHO), total volatile organic compounds (TVOC), radon (Rn) and airborne bacteria count (ABC). However, technical difficulties have been reported during the full assessment of these pollutants. This study hence investigates the feasibility of a preliminary screening process for presumptive detection of IAQ problems in an airconditioned environment. Specifically, a simple screening test at certain probability of unsatisfactory IAQ for air-conditioned offices, together with an ‘IAQ index’ which employs the average fractional dose to certain exposure limits of a few ‘most representative’ air pollutants (rather than all of the listed nine) was proposed. This is an alternative for routine inspection in determining the asymptomatic IAQ unsatisfactory for some air-conditioned offices of Hong Kong. And it was evaluated in terms of the test sensitivity, specificity and predictive values. The screening test would be a useful tool for policymakers, building owners and professionals to identify offices with probable IAQ problems and to make decisions on resources for efficient mitigation actions.