Introduction: As humans spend 90% of their time inside, indoor air quality (IAQ) is critical for occupant health. The primary concern associated with low IAQ is its impact on employees’ health, comfort, and productivity. In accordance with the Industry Code of Practice on Indoor Air Quality 2010 (ICOP IAQ 2010), a ten-parameter assessment was conducted in the office of the transformer manufacturing factory in Selangor, Malaysia. Methods: The measured parameters are temperature, air movement, relative humidity, carbon dioxide (CO2 ), carbon monoxide (CO), formaldehyde (CH2 O), particulate matter (PM10), total volatile organic compounds (TVOCs), total fungal count (TFC), and total bacterial count (TBC). This study employed both qualitative and quantitative approaches by distributing questionnaires (N = 42), and measuring the indoor air quality parameters with integrated equipment at selected stations and comparing them to the ICOP IAQ 2010 standard. Results: A majority of the measures, with the exception of air movement, CO2 , and TBC, complied with the ICOP IAQ 2010 standards. The one-way ANOVA test showed that there were significant differences (p < 0.05) for the parameters of temperature, PM10, and TVOCs. The ChiSquare test revealed that sleepiness was a symptom of the sick building syndrome, affecting both male and female employees the most frequently and significantly. Conclusion: Air movement, CO2 , and TBC values that did not meet ICOP IAQ 2010 requirements revealed poor IAQ at the study site, which could have a negative influence on the employees’ health. To cut down on air pollution, the improvement on the ventilation system should be done to reduce the risks to the employees’ health.