Airborne bacteria and fungal spores in the indoor environment. A case study in Singapore

Abstract

The concentration of airborne fungal spores and bacteria as related to room temperature, humidity and occupancy levels within a library building in Singapore was determined. Measurement of indoor air quality with respect to microorganisms is of particular importance in tropical environments due to the extensive use of air-conditioning systems and the potential implications for human health. This study has revealed a number of interesting relationships between the Concentrations of fungal spores and bacteria in relation to both environmental and human factors. The levels of fungal spores measured in the indoor environment were approximately fifty times lower than those measured outside, probably because of the lowered humidity caused by air-conditioning in the indoor environment. The variation in fungal spore concentration in the outdoor environment is likely to be due to the diurnal periodicity of spore release and the response to environmental factors such as light temperature and humidity The indoor concentration of fungal spores in air was not clearly correlated to concentrations measured in air outside of the library building and remained relatively constant, unaffected by the difference in the numbers of occupants in the library. In contrast, the indoor concentrations of bacteria in air were approximately ten times higher than those measured outdoors, indicating a significant internal source of bacteria. The elevated levels of indoor bacteria were primarily attributed to the number of library occupants. Increased human shedding of skin cells, ejection of microorganisms and particulates from the respiratory tract, and the transport of bacteria on suspended dust particles from floor surfaces probably accounts for the strong positive correlation between occupancy levels and the concentration of bacteria in internal air.

Assessment of bio-contaminants during COVID-19 outbreak from the indoor environment of Hail city, Kingdom of Saudi Arabia

“…There was no significant (p>0.05) association between sample collection time and types of bacterial isolates. Our results agree with previous studies that major sources of micro-contaminants attributed by humans' activities and human occupancy in residential areas [ 26 - 28 ]. Similarly, some other studies also reported that the nature of human contact and human behavior has great influence on in door environment [ 29 , 30 ] for instance, presence of bacteria in the kitchen surface area is influenced by the various kind of food [ 31 ], and surfaces area most often affected by hands containing higher concentrations of skin flora [ 32 ].…”

A Study of Microbe Air Levels in Selected Rooms of a Hospital Cultivated on Two Culture Medias

“…This indicated that indoor environment of each selected location in the hospital provides more favorable conditions for the survival of fungi. In addition, chloramphenicol used in RBCA media was included for the elimination of bacterial colonies in fungal culture while rose Bengal reduced the growth of fungi which eased identification of individual colonies [24]. This result is in line with the finding of earlier researcher by Guiamet et al [25], who studied in indoor air sampling showed the similar identification of fungi that were Aspergillus sp.…”

The Abundance and Diversity of Antibiotic Resistance Genes in the Atmospheric Environment of Biology Laboratories and Surroundings

“…The variations in the abundance of cultivable bacteria concentration in the air samples of laboratories and surroundings Cultivable airborne bacteria concentration of all samples varied from 1 CFU/m 3 , sample RL2 to 41 CFU/m 3 , sample CO3 (Figure.2), signi cantly lower than the cultivable airborne bacteria concentrations of library, hospital, other indoor environmental air samples and outdoor air samples such as wastewater treatment plant measured with tryptic soy agar (TSA) and blood agar (BA) medium in previous studies[15,[54][55][56].…”