Urban Air Quality Management: Detecting and Improving Indoor Ambient Air Quality

Abstract

Current air pollution management and air quality control are primarily focused on outdoor and atmospheric issues. In major cities today with large numbers of shopping malls, offices and public administration centers which act as public spaces, contaminated indoor air could be public health hazards. In Singapore, diagnosing the causes of ``sick building syndrome{''} is as important as treating outdoor pollution as its workforce is increasingly service-oriented and many of whom spend a substantial amount of time working in air-conditioned premises. It is known that indoor air quality (IAQ) can be easily and adversely affected by gas pollutants which are internally generated or infiltrated from external sources. One important and practical example is carbon monoxide (CO) which can be emitted at high concentration levels in an urban structure by burning of tobacco and incense, and by incomplete combustion from gas stoves and fuel engines used in renovation work. In this research, the decay rates of CO concentration (ppm) in air were measured accurately using the Fourier transform infrared spectroscopy in the 2,050-2,230 cm(-1) wavenumber region. High levels of CO were obtained from sidestream environmental tobacco smoke (ETS). From the modeling of the decay curves of CO concentration with time, the air exchange rates in air change per hour (ACH) were derived for six different ventilation rates. They were found to be from 2.53 to 8.63 ACH. The ventilation rates for CO contained in a chamber were varied using different window areas. Half-lives of the CO decays at six different air exchange rates were also determined and found to decrease from 16.4 to 4.8 min as the air exchange rate increases. The implications of air exchange rate on the decay of indoor CO in ETS were discussed with reference to IAQ in air-conditioned buildings in Singapore, and to IAQ in general urban settings.