The objective of this paper is to examine the building ventilation systems and concentration of selected indoor air pollutants for the pharmaceutical lab. Chromatography and chemistry labs in the building were selected for this study to represent the IAQ status in the premises with different HVAC system design and location. The result revealed that all gas contaminants are below the threshold limits recommended by American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE). Dust particles does not fulfill the guides of Ministry of Health (Malaysia). Chromatography unit indoor air quality is generally better than the chemistry unit. The average relative humidity of 60.5% was slightly exceeded the ASHRAE threshold limit. The Computational Fluid Dynamic (CFD) simulation showed the concentration of the particulates or airbornes increased towards the floor.