INDOOR AND OUTDOOR BIOAEROSOL SAMPLING AND BACTERIAL COUNTING ANALYSIS

Abstract

Bioaerosol concentrations are significantly affected by environmental conditions. Therefore, bioaerosol sampling is important to monitor and control air quality, in particular to control airborne diseases. This study was conducted in August 2019 to investigate the air quality in a government premise in Selangor, Malaysia. The sampling sites were selected randomly from the same building. One of the samples was collected from a garden as outdoors sample, while others were collected indoors, which included the pantry, toilet, staff rooms, store rooms, meeting room, prayer room, exhibition hall and training room. The eleven sampling sites differ from each other in terms of the presence of personnel, windows, air conditioning system, water source, organic substrates and flooring materials. For bioaerosol sampling, the Andersen impaction method was applied using Nutrient Agar (NA) non-selective media plates. Three units of biological air samplers (SKC Quick Take 30, USA) with setting of 2 min sampling time and volume flow rate of 28.3 L/min were used in each sampling location. The plates were incubated at 35 ºC for 24 h and underwent the plate count
process using an automatic colony counter (Interscience Scan 4000, USA). The total number of bacterial colonies for 24 and 48 h were counted and recorded before the bacterial concentrations were calculated using the concentration of biological contaminants calculation formula. The results showed that all the indoor and outdoor locations were still at healthy levels and do not exceed the maximum limit of 1,000 CFU/m3 for the total number of bioaerosol particles that has been recommended by the National Institute of Occupational Safety and Health (NIOSH) and American
Conference of Governmental Industrial Hygienists (ACGIH). However, the staff room exceeded the culture count for total bacteria of 500 CFU/m3 that was recommended by ACGIH. The higher bacterial concentrations in the staff room and prayer room than the garden could be influenced by several factors including presence of personnel, air ventilation, flooring material, water sources and organic substrates. In conclusion, the airborne bacteria presence could possibly originate from outdoor sources, with textile and humans as the main vectors of the contamination in both locations,
especially during the haze period.
Keywords: Bioaerosol; indoor and outdoor environments; biological air sampler; automatic colony counter; haze period.

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