Assessment of indoor air quality in air-conditioned small business units with no mechanical ventilation

Abstract

Shophouses, a common building type in Singapore, host small business units typically cooled by non-mechanically ventilated strategies. Activities in these spaces include cooking food and handling nail and hair products, which emit volatile organic compounds (VOCs), carbon monoxide (CO), and other airborne contaminants that could compromise indoor air quality (IAQ). This study assessed potential IAQ risk by quantifying total VOCs (TVOC), formaldehyde, carbon dioxide (CO2), and CO levels in 100 air-conditioned small business units in Singapore's shophouses. The median (maximum) concentrations across all units were TVOC:179 (54,880 ppb), formaldehyde:0 (1.0 ppm), CO2:586 (2750 ppm) and CO:0 (0.5 ppm). The majority (90%) of the units did not have mechanical ventilation provision, and TVOC and formaldehyde levels correlated significantly with corresponding CO2 levels (p ≤ 0.05). The highest levels of TVOC and formaldehyde were measured at nail salons (TVOC: 54,880 ppb, formaldehyde: 1.0 ppm). Improving ventilation combined with use of alternative low-emission products could improve IAQ in small business units.