Assessment of indoor air quality in an air-conditioning split units (ACSU) office building

The indoor air quality (IAQ) in Air-Conditioning Split Units (ACSU) offices depends mainly on recirculated indoor air that has gone through filters. Workers usually spend eight hours in the office space with restricted air circulation. An IAQ assessment was conducted at the administrative office space, USM, to investigate conditions in an ACSU office space; from 8.00 a.m. to 6.00 p.m. It starts with a walkthrough survey followed by the filling of questionnaires, with a sample size of 11 workers for insights into the office operations. The specific physical parameters (T, RH, and AM) and indoor air contaminants (CO, CH₂ O, O₃ , PM₁₀, TVOC, TBC, TFC, and CO₂ ) were conducted at three points indoor and one point outdoor. The T and RH were within the acceptable range of 23-26°C and 40-70%, respectively by ICOP, while the AM was very low and less than the acceptable threshold range of 0.15-0.5 m/s at 0.08 m/s, 0.04 m/s, and 0.02 m/s at Point 1, Point 2, and Point 3, respectively. The indoor air contaminants (CO, CH₂ O, O₃, TVOC, PM₁₀, and TFC) met the standard level of ICOP, except for TBC and CO₂ . TBC exceeded the ICOP limit (500 cfu/m³) at 1000 cfu/m³ and 1500 cfu/m³ , at Point 1 and Point 2, respectively, whereas CO₂ concentrations exceeded it (1000 ppm) at 1008.93 ppm at Point 2. In essence, the results indicated that the ACSU office space with restricted air circulation was inadequately ventilated as the AM were low, resulting in, high CO₂ concentrations and high TBC. Secondly, the indoor air contaminants (CO, CH₂ O, TVOC and CO₂) were higher than those outdoors. The questionnaire survey results reported that the highest present symptom experienced by the workers was drowsiness with 64 %. Therefore, it is prudent to ensure the IAQ is within the acceptable limit to avoid any possible health effects on workers within an office space.