Indoor bacterial load and its correlation to physical indoor air quality parameters in public primary schools

Abstract

Background: Poor indoor air quality is a great problem in schools due to a high number of students per classroom, insufficient outside air supply, poor construction and maintenance of school buildings. Bacteria in the indoor air environment pose a serious health problem. Determination of bacterial load in the indoor environment is necessary to estimate the health hazard and to create standards for indoor air quality control. This is especially important in such densely populated facilities like schools. Methods: Institutional based cross-sectional study was conducted among 51 randomly selected classrooms of eight public primary schools from March 29–April 26, 2018. To determine the bacterial load passive air sampling settle plate method was used by exposing a Petri dish of blood agar media for an hour. The Pearson correlation matrix was employed to assess the correlation between bacterial load and physical parameters. Results: The grand total mean bacterial load was 2826.35 CFU/m3 in the morning and 4514.63 CFU/m3 in the afternoon. The lowest and highest mean bacterial load was recorded at school 3 (450.67 CFU/m3) and school 5 (7740.57 CFU/m3) in the morning and afternoon, respectively. In the morning relative humidity (r = −0.7034), PM2.5 (r = 0.5723) and PM10 (r = 0.6856); in the afternoon temperature (r = 0.3838), relative humidity (r = − 0.4014) were correlated with indoor bacterial load. Staphylococcus aureus, Coagulase-negative Staphylococcus species and Bacillus species were among isolated bacteria. Conclusions: High bacterial load was found in public primary schools in the Gondar city as compared to different indoor air biological standards. Temperature, relative humidity and particulate matter concentration (PM2.5 and PM10) were associated with the indoor bacterial load. Staphylococcus aureus, Coagulase-negative Staphylococcus species and Bacillus species were among isolated bacterial species. Attention should be given to control those physical factors which favour the growth and multiplication of bacteria in the indoor environment of classrooms to safeguard the health of students and teachers in school.

Effect of Air Purifier Use in the Classrooms on Indoor Air Quality—Case Study

“…Poor indoor air quality, which is a serious problem in schools due to the large number of students in the classroom, and insufficient internal air exchange, were reported by Andualum et al [26]. Similar to our study, those authors noted a clear increase in bacterial numbers after classes, and that temperature, relative humidity, and dust concentrations were associated with bacterial contamination.…”

Microbial, environmental and anthropogenic factors influencing the indoor microbiome of the built environment

“…Ninty‐five percent of the airborne particles were having a diameter of less than 1 µm, which showed a significant correlation with concentrations of culturable airborne bacteria [30]. A strong correlation was found between PM 2.5 and total airborne bacteria [13,86]; however, Bragoszewska et al [87] found their negative correlation. Some studies showed no significant correlation between fungal levels and particle counts [30], whereas Armadans‐Gil et al [88] observed a positive correlation between airborne fungi and particle sizes greater than 0.5 µm as well as greater than 1 µm in the hospital rooms.…”

Bioaerosol Assessment of Selected Offices within a Polytechnic

“…Again, Sule, et al [27] stated that ventilation, health status, human traffic and activities are some of the factors which could increase the level of microorganisms in the indoor air. The variation of bacterial load in indoor environments could also be due to environmental factors such as ventilation system of rooms, temperature, humidity, and particulate matter concentration [28].…”