Microbial Assessment of Indoor Air Quality of Laboratory Sections in Obong University, Obong Ntak, Nigeria

Representative assessment parameters are proposed for indoor air quality (IAQ) audit in various strategies and guidelines.1 In Hong Kong, assessment of indoor airborne fungi is not incorporated in many IAQ audits of air-conditioned offices, although the exposure to airborne fungi could cause a variety of adverse health effects. An IAQ assessment for a local office will audit 12 parameters, including air temperature, relative humidity, air velocity, carbon dioxide, carbon monoxide, respirable suspended particulates, nitrogen dioxide, ozone, formaldehyde, total volatile organic compounds, radon, and airborne bacteria. This paper reviews recent studies of the indoor airborne fungi levels and IAQ assessments in some air-conditioned offices of Hong Kong and evaluates the contribution of the airborne fungi to an unsatisfactory IAQ in the environment. The unsatisfactory rates regarding the assessment parameters were evaluated using the Monte Carlo simulations with measured data in Hong Kong Offices. In particular, the impact of selecting representative IAQ assessment parameters was examined against an express assessment protocol (EAP), which assessed some dominant contributors of unsatisfactory IAQ.2 The results reported that the three top ranked contributors for unsatisfactory IAQ were total volatile organic compounds (TVOC), indoor airborne fungi count (AFC) and airborne bacteria count (ABC) for air-conditioned offices of Hong Kong. Practical applications: This study has shown that the assessments of airborne fungi levels in office environment is an important issue and further investigations for the airborne fungi in the IAQ audits were thus recommended. The results of this study could be a useful source of reference for policymakers in evaluation of an effective IAQ assessment protocol with some representative IAQ assessment parameters.

Wholesale traditional markets (WTMs) have established the most comprehensive and advanced auction systems for fresh seafood, meat, and fruits. Understanding the levels of bioaerosols of different sizes in WTMs can help to develop strategies to reduce the spread of infectious diseases. This study was aimed at analyzing and comparing the size distributions of culturable airborne bacteria (AB) and airborne fungi (AF) in a typical wholesale traditional fish market (WTFM). The AB and AF concentrations in the WTFM were relatively both high during and after the operation. The average AB concentration significantly increased from 4.73 × 10 3 during operation to 8.58 × 10 3 CFU/m 3 after operation. The highest concentration of AB was observed at the fourth stage (2.1–3.3 μ m), accounting for 26.22% and 28.15% of the total AB measured during and after operation, respectively. The average AF concentration remained steady from 2.77 × 10 3 during operation to 2.53 × 10 3 CFU/m 3 after operation. The fourth stage also showed the highest AF concentration postoperation, comprising 35.47% of the total AF measured. Particles in this size range can be easily inhaled and deposited in the bronchial tubes, posing significant health risks. This study identified four and two types of possible pathogenicity in dominant AB and dominant AF, respectively. Commonly pathogenic Flavobacterium spp. frequently found in seafood and the highly pathogenic AF species Aspergillus tamarii and Aspergillus ochraceus were also detected. These pathogens and ultrafine biological aerosols (< 1 μ m) can induce respiratory conditions such as aspergillosis. Based on these findings, the WTFM management should implement targeted interventions to reduce the concentration of harmful particles.

Airborne bacteria and fungi in hospital environments are of great concern due to their potential role as a source of nosocomial infections. The aim of this study was to evaluate concentration and diversity of airborne bacteria and fungi in relation to particle mass concentration in sensitive wards of a pediatric hospital. The study was performed in the cardiac care unit (CCU), the neonatal intensive care unit (NICU), the cancer blood ward (BW), the ENT (ear, nose, throat) operation room (OT1) and the eye operation room (OT2). The air samples were collected by impaction using the single-stage Andersen sampler. The flow rate and sampling time of the pump were adjusted to 28.3 l/min for 5 min. The mean concentration of indoor airborne fungi and bacteria ranged from 0–63 to 19–356 CFU/m3, respectively. OT2 and CCU wards were the most contaminated wards for airborne bacteria and fungi, respectively (243 ± 77 vs. 30 ± 7 CFU/m3). The airborne Gram-positive cocci (Staphylococcus and Micrococcus) were the most detected bacterial genera (75%) in all indoor air samples, and the most prevalent genera in indoor environment were Cladosporium spp. (19%) followed by Penicillium spp. (16%), Aspergillus spp. (16%) and Paecilomyces spp. (10%). Results showed that the outdoor airborne bacteria and PM concentration at different sizes were significantly higher than indoors, suggesting that the indoor airborne particle may have originated from the outdoor air. There were significant positive relationships between indoor airborne fungi concentrations with indoor PM2.5 and PM10.

Air is an important part of human life. However, air can be contaminated with microorganisms such as airborne bacteria and fungi. Temperature and relative humidity in a room can have an impact on the quantity of airborne bacteria and fungi. This study aims to figure out the correlation between the number of airborne bacteria and fungi with temperature and relative humidity. In 15 rooms of Microbiology laboratory, NA and SDA Petri plates were placed, after incubation, the number of colonies in each plate was counted. Pearson test was conducted with SPSS to determine the correlation between temperature and relative humidity to the number of airborne bacteria and fungi. The highest number of airborne bacteria was in the reading room (352 CFU/m3), while the lowest number was in the laundry room (13 CFU/m3) and the highest number of airborne fungi was in the Mycology room (156 CFU/m3), while there were no airborne fungi found in the urine and laundry rooms. Based on the results of the Pearson test, it was found that the value of p = 0.668 (p> 0.5) showed that there was no correlation between temperature and the number of airborne bacteria and fungi. Based on the results of the Pearson test, the value of p = 0.745 (p> 0.5) showed that there was no correlation between relative humidity and the number of airborne bacteria and fungi. There is no correlation between temperature and relative humidity with the number of airborne bacteria and fungi.

Inactivation of airborne microbial contaminants by a heat-pump-driven liquid-desiccant air-conditioning system

To characterize the emission of microbial aerosols from the widely used municipal sewage treatment plants (MSTP) in China, an Andersen six-stage impactor and the culture method were employed to determine the concentrations and size distributions of airborne viable bacteria, fungi and actinomycetes in a sewage treatment plant with an oxidation ditch process in Xi’an in summer. The results showed that the concentrations and size distributions of each of the airborne microorganisms varied greatly at different phases of sewage treatment process. The highest bacteria (7866 ± 970 CFU/m 3 ) and actinomycetes concentrations (2139 ± 229 CFU/m 3 ) were found in the sludge-dewatering house while the highest fungi concentration (2156 ± 119 CFU/m 3 ) at the oxidation ditch. The particle size distributions showed that similar singlepeak pattern for airborne actinomycetes, bacteria and fungi. Another important finding was that about 52% of airborne bacteria, 62% of airborne fungi and 65% of airborne actinomycetes were in respirable size range (less than 3.3 μm), indicating that most microbial aerosols from MSTP could easily penetrate into the human alveolus. Finally, the order of the count median diameters of different microbial aerosols was found to be similar at each phase, that is, airborne bacteria > airborne fungi > airborne actinomycetes. This implied that airborne actinomycetes emitted from MSTP might have a more significant effect on public health and urban air quality than bacteria and fungi.

The exposure level and distribution characteristics of airborne bacteria and fungi were assessed in the workers' activity areas (station office, bedroom, ticket office and driver's seat) and passengers' activity areas (station precinct, inside the passenger carriage, and platform) of the Seoul metropolitan subway. Among investigated areas, the levels of airborne bacteria and fungi in the workers' bedroom and station precincts were relatively high. No significant difference was found in the concentration of airborne bacteria and fungi between the underground and above ground activity areas of the subway. The genera identified in all subway activity areas with a 5% or greater detection rate were Staphylococcus, Micrococcus, Bacillus and Corynebacterium for airborne bacteria and Penicillium, Cladosporium, Chrysosporium, Aspergillus for airborne fungi. Staphylococcus and Micrococcus comprised over 50% of the total airborne bacteria and Penicillium and Cladosporium comprised over 60% of the total airborne fungi, thus these four genera are the predominant genera in the subway station.

Exposure level and distribution of airborne bacteria and fungi in an urban utility tunnel: A case study

This study thoroughly examined indoor air quality in six chain stores in Isfahan, Iran and involved the measurement of air pollutants (PM2.5, PM10, NO2, SO2, CO2, bacteria and fungi), alongside noise levels and thermal comfort over four seasons (2023-2024). To address the diversity of pollutants and enhance decision-making, an indoor air quality index (IAQI) was proposed, based on the importance coefficient and pollutant duration of presence. The results revealed that concentration of PMs in the autumn was relatively higher than in other seasons, with a strong correlation (R2 = 0.926) observed between PM2.5 and PM10. For other parameters, levels remained within acceptable limits; however, noise levels in all seasons and stores exceeded standards. Airborne bacteria (312-1,007 CFU/m³), dominated by Rhodococcus and Micrococcus, and airborne fungi (639-1,332 CFU/m³), mainly represented by Aspergillus and Penicillium, were detected. Overall, most stores exhibited intermediate biological contamination levels across all seasons. The proposed IAQI for all seasons and stores, with some allowance for variability, falls into class D, corresponding to an intermediate/acceptable indoor air quality level. In conclusion, the air quality in studied stores does not pose an immediate concern for customers and visitors, continuous monitoring and the implementation of ventilation equipment are recommended to ensure the well-being of store personnel.

Poor indoor air in schools has become a wide-spread problem with serious effects on occupant health. Resultant costs can be considerable at both local and national government levels. These include absenteeism and rehabilitation as well as building alterations and even demolition and rebuilding. This project aims to show factors contributing to health problems in Swedish schools. It includes a literature survey and particle measurements taken during various activities. Due to the fact that today there is no standard for indoor air quality (IAQ) in schools, in this project we used the outdoor air surrounding the building as an indicator. Results showed that indoor school environments had high airborne pollution levels, to a degree that probably causes health problems for many people. Regarding IAQ, this project shows the importance of taking into consideration choices in activities and furnishing of the building.

Characterization of airborne bacteria and fungi at a land-sea transition site in Southern China

The main purpose was to validate the use of outdoor-indoor volumetric impaction sampler with Hirst-type spore traps (HTSTs) to continuously monitor fungal load in order to prevent invasive fungal infections during major structural work in hospital settings. For 4 weeks, outdoor fungal loads were quantified continuously by 3 HTSTs. Indoor air was sampled by both HTST and viable impaction sampler. Results were expressed as particles/m3 (HTST) or colony-forming units (CFU)/m3 (biocollector). Paired comparisons by day were made with Wilcoxon’s paired signed-rank test or paired Student’s t-test as appropriate. Paired airborne spore levels were correlated 2 by 2, after log-transformation with Pearson’s cross-correlation. Concordance was calculated with kappa coefficient (κ). Median total fungal loads (TFLs) sampled by the 3 outdoor HTSTs were 3,025.0, 3,287.5 and 3,625.0 particles/m3 (P = 0.6, 0.6 and 0.3).—Concordance between Aspergillaceae fungal loads (AFLs, including Aspergillus spp. + Penicillium spp.) was low (κ = 0.2). A low positive correlation was found between TFLs sampled with outdoor HTST and indoor HTST with applying a 4-hour time lag, r = 0.30, 95% CI (0.23–0.43), P<0.001. In indoor air, Aspergillus spp. were detected by the viable impaction sampler on 63.1% of the samples, whereas AFLs were found by HTST-I on only 3.6% of the samples. Concordance between Aspergillus spp. loads and AFLs sampled with the 2 methods was very low (κ = 0.1). This study showed a 4-hour time lag between increase of outdoor and indoor TFLs, possibly due to insulation and aeraulic flow of the building. Outdoor HTSTs may permit to quickly identify (after 48 hours) time periods with high outdoor fungal loads. An identified drawback is that a too low sample area read did not seem to enable detection of Aspergillaceae spores efficiently. Indoor HTSTs may not be recommended at this time, and outdoor HTSTs need further study. Air sampling by viable impaction sampler remains the reference tool for quantifying fungal contamination of indoor air in hospitals.

Jumping on the bed and associated increases of PM10, PM2.5, PM1, airborne endotoxin, bacteria, and fungi concentrations

Indoor airborne bacteria and fungi levels can be selected as indicators of a healthy indoor environment. This study investigated the relationships between the airborne bacteria levels, fungi levels, and thermal environmental parameters, i.e., air temperature and relative humidity, in some offices with a Mechanical Ventilation and Air-Conditioning (MVAC) system operating. A total of 101 samples were collected from two typical Hong Kong air-conditioned office premises. There was evidence that the operation of the MVAC system would have significant influence on both of the indoor airborne bacteria and fungi levels. The results showed that no significant difference in airborne bacteria and fungi levels was observed between offices having similar thermal environments ( p &gt; 0.05). However, significantly higher airborne bacteria and fungi levels were found in the same office during non-office hours when the air-conditioning system was shut down ( p&lt;0.03). It was also reported that the airborne bacteria and fungi levels would be correlated with the thermal environmental parameters in some offices ( p&lt;0.0001).

The concentration of airborne bacteria and fungi in public buildings is regulated by law in Korea. Levels are investigated during the moderate seasons, spring (March—May) and autumn (September—November), using a six-stage cascade impactor. Total concentrations of airborne bacteria and fungi range from 290 to 940 cfu · m-3 and 330 to 540 cfu · m -3, respectively. The levels of airborne bacteria and fungi are significantly highest in a kindergarten building and lowest in an elderly welfare facility ( p&lt;0.05). The ratio of respirable to total concentration range from 30 to 40% for airborne bacteria and from 55 to 70% for airborne fungi but there is no significant difference among the public buildings examined ( p&gt;0.05). The mean ratios of indoor and outdoor concentrations of airborne bacteria and fungi are below 1.0 regardless of the fraction of particle size and building type. The indoor concentration of airborne bacteria and fungi do not correlate significantly with indoor temperature and relative humidity ( p&gt;0.05). However, this does have a significant positive correlation with CO2 and the number of people per area of the sampling site ( p&lt;0.05), which implies that the activity of residents has considerable effect on the levels of both airborne bacteria and fungi.