Survey of Airborne Microorganisms in an Arcade-Type Traditional Market in Anseong, South Korea.

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<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>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>0.05). However, this does have a significant positive correlation with CO2 and the number of people per area of the sampling site ( p<0.05), which implies that the activity of residents has considerable effect on the levels of both airborne bacteria and fungi.

Distribution characteristics of airborne bacteria and fungi in the feedstuff-manufacturing factories

Airborne microbiological characteristics in public buildings of Korea

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.

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

Microbial aerosol whose species and concentrations are closely related to human health is ubiquitous. The effect of microbes on human and animal health and production performance is, in many cases, caused by the spreading of air. Samples in this experiment were from a live poultry market (LPM) in Tai’an, China, collected three times a day (8 am, 14 pm, and 20 pm) over three consecutive days each month for 11 months (Original sampling plan was a year, the government due to the environmental protection, the was LPM closed). The main indicators of the test were concentrations of cultural airborne bacteria, airborne fungi, and Gram-negative bacteria. At the same time the species of Gram-negative bacteria and the concentration of endotoxin were tested. Temperature and humidity were recorded in the process of each sampling. The results showed that the diurnal variation of the concentration of bacteria, fungi, and Gram-negative bacteria is higher in the morning and evening, but lower at noon. The concentrations of airborne bacteria and Gram-negative bacteria increased in earlier months and decreased in later months, with the peak appearing in the autumn. The concentration of fungi showed a decrease first and then tended to stabilize, with the peak occurring in the spring. The concentration peak of endotoxin occurred in the summer. Endotoxin levels were significantly correlated with humidity (r = 0.90, p < 0.01). Most bacteria were distributed at the third and fourth stages (2.1–4.7 μm) in the ANDERSEN-6 sampler. The dominant species of Gram-negative bacteria during the four seasons were Pseudomonas aeruginosa, Acinetobacter, Klebsiella pneumoniae, and Salmonella. In China, people have a habit of eating fresh poultry, LPM distribution is widespread, stream of people and traffic flow are large, easily caused the spread of bacteria and viruses, so the LPM microbial aerosol research have significant public health implications.

To quantify characteristics of bioaerosols in university indoor environments, concentration and size distribution of airborne culturable bacteria and fungi were examined in four types of buildings of Chang'an University in Xi'an, China, from March, 2012 to February, 2013. Indoor temperature and relative humidity (RH) were also measured to determine correlations between bioaerosols and environmental parameters. Results showed that concentration and size distribution of airborne bacteria and fungi varied in various indoor environments due to the appearance of different indoor sources and human occupancy. The highest mean concentrations of airborne bacteria and fungi were found in the canteen (1,025±91 and 699±57 CFU/m3), followed by the clinic and dormitories, and the lowest in classrooms (479±66 and 345±15 CFU/m3). Airborne bacteria and fungi here showed higher concentrations than those of western universities. Similar seasonal variations of airborne fungal concentrations were observed for all indoor environments, with higher levels in fall and winter and lower in spring and summer. Indoor temperature showed more significant correlation with bioaerosols than RH in all indoor environments. Another important finding was that more than 75% bacterial and fungal aerosols were in respirable size range in each indoor environment.

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.

Assessment of airborne bacteria and fungi in pig buildings in Korea

The present study sought to evaluate the energy consumption, indoor air quality and concentration of airborne bacteria and fungi in the Sapporo underground walkway, which is in a cold region of Japan. The energy consumption, temperature, relative humidity, and carbon dioxide concentrations of the underground walkway were investigated for 4 years from its opening in 2011 (until 2014). The temperature, relative humidity, and carbon dioxide concentrations were automatically detected using sensors and data from Sapporo city hall. To evaluate the microbial contamination in the ventilation system and indoors, the concentrations of airborne bacteria and fungi were measured on 2 days (a weekday and a weekend day) during opening hours in both summer and winter. The concentration of airborne microbes in the supply air, indoor air, and outside air was compared. Species of airborne bacteria were identified using 16S rDNA sequence analysis. The energy use intensities were decreased in 2013, when the walkway temperature was changed during both winter and summer. The carbon dioxide concentration in the walkway was maintained below 1000 ppm. The number of airborne bacteria and fungi in the supply air from the ceiling diffuser was lower than those in the outdoor and indoor air. These results indicate that both energy consumption and indoor air quality were maintained in the walkway throughout the 4-year period. This study could be helpful for developing the related standards for indoor air quality and for developing control strategies to properly operate air conditioning and ventilation systems in underground spaces.

Bioaerosols have a major negative effect on air quality and on public health by causing the spread of diseases. This study evaluated the bioaerosol composition and variation in a semi‐arid megacity of northwest China from October 2019 to January 2020 using an Andersen six‐stage impactor sampler. The size distribution, diurnal variations of the concentrations of airborne bacteria, airborne fungi, and total airborne microbes (TAM) were investigated in autumn and winter. The mean concentrations of airborne bacteria, fungi, and TAM were 523.5 ± 301.1 colony‐forming units (CFU)/m3, 1318.9 ± 447.8 CFU/m3, and (7.25 ± 1.90) × 106 cells/m3, respectively, in autumn and 581 ± 305.4 CFU/m3, 1234.4 ± 519.9 CFU/m3, and (5.96 ± 1.65) × 106 cells/m3, respectively, in winter. The mean bioaerosol concentrations were slightly higher on nonhaze days than on haze days, but the difference was not statistically significant. Higher ambient particulate matter levels and atmospheric oxidation capacity inhibited bacteria survival. The diurnal maximum bioaerosol concentration was observed in the morning in autumn, whereas in winter, bioaerosols did not exhibit such a distribution, the impact of human activities on bioaerosols was still uncertain. The size of airborne bacteria exhibited a bimodal distribution, whereas a unimodal pattern was observed for fungi and TAM. Most bacteria, fungi, and TAM were distributed in the respirable ranges from trachea and primary bronchi to alveoli, indicating that bioaerosols have a high risk of being inhaled and causing respiratory diseases in Xi’an.

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 (&lt; 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 are an ongoing problem in hospitals. Because of the antimicrobial activities of essential oils (EOs) dispersion of EOs into the air may help to reduce this contamination. The aim of this study was to evaluate the efficacy of the dispersion of selected EOs in reducing the microbial contamination in two hospital wards. The study was carried out at two wards of a 1,227-bed acute-care hospital in Austria. The concentration of airborne bacteria and fungi was measured in patient rooms before and after dispersion of a mixture of Citrus limon EO and Abies alba EO. Before dispersion of the EOs in both wards the mean concentration of bacteria was in a typical range (123 colony forming units (CFU) m–3 and 104 CFU m–3) while the mean concentration of fungi differed substantially (155 CFU m–3 and 28 CFU m–3). After dispersion of the EOs, a reduction in both bacterial and fungal contamination was observed. In the first two hours the mean concentration of airborne bacteria and fungi was reduced by approximately 40% and 30%–60% respectively. The selected EO mixture is effective in reducing the microbial contamination of the indoor air.

The relationship between the viable airborne bacterial and fungal concentrations and the respirable particulate matter with aerodynamic diameter less than 10 μm (PM10), 2.5 μm (PM2.5), and 1 μm (PM1) in the ambient air was studied. An Andersen six stage viable particle sampler and a MAS 100 sampler were used for microbial measurements. Duplicates of samples were collected at each sampling period (20 campaigns in total) at a residential site in the city of Chania (Crete, Greece) during April, May and June 2008. Mean concentration of the total sum of the six size fractions was 79 + 41 CFU m-3 for mesophilic heterotrophic bacteria, whereas for mesophilic fungi it was five times higher (395 + 338 CFU m-3). Particulate matter measurements at the same time period at the same site revealed that the mean concentrations of PM10, PM2.5, and PM1 were 46 + 14, 35 + 14, and 28 + 12 μg m-3, respectively, whereas the mean cumulate counts of PM1 particles was 5,059 + 1,973 particles cm-3. The mean arithmetic concentration of the size distribution of the airborne fungi had a maximum at aerodynamic diameters between 2.1 and 3.3 μm. However, a maximum was not observed for the mean arithmetic concentration of the size distribution of the airborne heterotrophic bacteria. It was also observed that concentrations of airborne bacteria and fungi outdoors were highly variable and do not correlate with the particle number (PM1) or mass concentration of PM10, PM2.5 and PM1. Thereby, the R2-values in all correlations were less than 0.3. However, the concentrations of airborne bacteria and fungi were decreased with increasing mass concentrations of PM10, PM2.5, or PM1 while were increased with increasing number concentration of PM1. In addition, the concentrations of airborne bacteria were increased with increasing concentrations of airborne fungi. Finally, the microbial or the particulate matter data did not correlate with meteorological parameters, such as temperature, relative humidity, wind speed and UV radiation in ambient conditions.

This study was conducted to evaluate the level of microbial contamination of indoor air during 3 years for two residences in one building equipped with heat recovery ventilation devices and located in Kimobetsu town of Hokkaido, Japan. This article documents a case study aimed at monitoring the microbes contaminations indoors for a safe use of energy saving ventilation devices and sanitary indoor air. This articles describes an investigative approach with three components. First, the authors evaluated the indoor air quality and microbial concentration by comparing the concentrations of particulate matter (PM10 and PM2.5), carbon dioxide, and airborne bacteria and fungi of indoor air and outdoor air during spring, summer and winter. Second, the microbial concentration inside an earth tube and a fixed sensible heat exchanger was evaluated by measuring the airborne microbial concentration of the supply air. Third, the authors assessed the possibility of microbial contamination inside the earth tube using the fungal index and by measuring temperature and relative humidity at the tube's outlet airflow. The results showed that the total concentration of airborne fungi was higher in summer than in spring or winter and that the fungal genera Cladosporium sp. and Penicillium sp. were dominant in the samples. Additionally, it was found that the environment inside the earth tube allowed easy growth of fungi from May to September with the highest fungal index measured in August. It was also confirmed that the earth tube did not affect the supply air for a building constructed 4 years ago.