Association Between Levels of Radon And Bioaerosols (Bacteria And Fungi) By Living Conditions

This study aimed to measure the levels of airborne radon (Rn) and bioaerosols—culturable airborne bacteria (CAB) and culturable airborne fungi (CAF)—in South Korea’s residential environments, considering living conditions such as the number of ventilations, number of windows, floors, temperature, and relative humidity. These levels were evaluated for 32 houses of residents from the socially vulnerable class. Rn gas and bioaerosols were sampled twice: in fall and summer. A self-report survey gathered residents’ information on their general characteristics (daily residence time, heating and cooking type, cleaning and washing cycle, etc.) and health condition scores (0–100 points) on the day of sampling. The range of Rn levels was 0.43–7.439 pCi/L with a median of 0.70 pCi/L. The CAB levels were 239–488 colony-forming unit (CFU)/m3 with a median of 309 CFU/m3, and CAF levels were 174–366 CFU/m3 with a median of 233 CFU/m3. Thus, this study found that semi-basement residential indoor environments negatively affected Rn and bioaerosol levels, and living in such residences resulted in high health condition scores.

Effect of Air Purification Systems on Particulate Matter and Airborne Bacteria in Public Buses

The indoor air quality in public transport systems is a major concern in South Korea. Within this context, we investigated the effect of air purification systems on the indoor air quality of intercity buses, one of the most popular transport options in South Korea. Air purifiers were custom designed and equipped with high-efficiency particulate air (HEPA) filters to remove particulate matter and ultraviolet light-emitting diodes (UV-LEDs) to remove airborne bacteria. To investigate the effectiveness of the air purification systems, we compared concentrations of particulate matter (PM2.5 and PM10), airborne bacteria, and carbon dioxide (CO2) in six buses (three with air purification systems and three without) along three bus routes (BUS1, BUS2, BUS3) in Gyeonggi Province, South Korea, between 6 April and 4 May 2021. Compared to the buses without air purification, those with air purification systems showed 34–60% and 25–61% lower average concentrations of PM2.5 and PM10, respectively. In addition, buses with air purification systems had 24–78% lower average airborne bacteria concentrations compared to those without air purification systems (when measured after 30 min of initial purification).

Investigation of Sources, Diversity, and Variability of Bacterial Aerosols in Athens, Greece: A Pilot Study

We characterized the composition, diversity, and potential bacterial aerosol sources in Athens’ urban air by DNA barcoding (analysis of 16S rRNA genes) during three seasons in 2019. Air samples were collected using the recently developed Rutgers Electrostatic Passive Sampler (REPS). It is the first field application of REPS to study bacterial aerosol diversity. REPS samplers captured a sufficient amount of biological material to demonstrate the diversity of airborne bacteria and their variability over time. Overall, in the air of Athens, we detected 793 operational taxonomic units (OTUs), which were fully classified into the six distinct taxonomic categories (Phylum, Class, Order, etc.). These OTUs belonged to Phyla Actinobacteria, Firmicutes, Proteobacteria, Bacteroidetes, Cyanobacteria, and Fusobacteria. We found a complex community of bacterial aerosols with several opportunistic or potential pathogens in Athens’ urban air. Referring to the available literature, we discuss the likely sources of observed airborne bacteria, including soil, plants, animals, and humans. Our results on bacterial diversity are comparable to earlier studies, even though the sampling sites are different or geographically distant. However, the exact functional and ecological role of bioaerosols and, even more importantly, their impact on public health and the ecosystem requires further air monitoring and analysis.

Investigations on Bacterial Load in the Rural and Urban Indoor and Outdoor Environment of Gwalior, Madhya Pradesh, India

Comparative analysis of airborne bacterial load in the rural and urban indoor and outdoor environment is of utmost importance to evaluate the wellbeing hazards linked with co3ntamination of airborne bacteria in the indoor environment. The present study was conducted during December, 2020 to March, 2021 among 50 randomly selected rural and urban (Adupurajagir and Gwalior, respectively) dwellings to determine the indoor and outdoor bacterial load. The mean load of 562.35 CFU/m3 airborne bacteria was recorded in the indoor environment of a modular kitchen in Gwalior city. The mean load of 2593.75 CFU/m3 bacteria was recorded in the indoor environment of the traditional kitchen in Adupurajagir village. In addition, bacterial load of respectively 1215.13 CFU/m3 and 783.03 CFU/m3 was calculated in the open space at both study sites. Based on morphological characteristics five bacterial species (spp.) were identified Staphylococcus aureus spp, Bacillus spp, Coagulase-negative Staphylococcus spp, E-coli spp, and Micrococcus spp. By gram staining method the most common bacteria were gram-positive (+ve) [n=85, 54.48% (37.17% cocci, 17.94% bacilli)] followed by gram-negative (-ve) [n=71, 45.51% (23.07% cocci, 21.79% bacilli)] identified. Pearson’s correlation coefficient was employed between bacterial load and physical factors of the indoor environment in the rural traditional kitchen. Bacterial load (CFU/m3) showed a significant correlation with temperature (p < 0.001). However, a non-significant correlation was recorded with relative humidity (p > 0.01). High bacterial load was found in the rural traditional kitchen’s indoor environment compared to urban modular kitchen. Outcomes from this study revealed that bioaerosol sampling could deliver fruitful knowledge about the variation of air quality and prevent possible hospital admissions.

A systematic review and meta-analysis of indoor bioaerosols in hospitals: The influence of heating, ventilation, and air conditioning

Objectives To evaluate (1) the relationship between heating, ventilation, and air conditioning (HVAC) systems and bioaerosol concentrations in hospital rooms, and (2) the effectiveness of laminar air flow (LAF) and high efficiency particulate air (HEPA) according to the indoor bioaerosol concentrations. Methods Databases of Embase, PubMed, Cochrane Library, MEDLINE, and Web of Science were searched from 1st January 2000 to 31st December 2020. Two reviewers independently extracted data and assessed the quality of the studies. The samples obtained from different areas of hospitals were grouped and described statistically. Furthermore, the meta-analysis of LAF and HEPA were performed using random-effects models. The methodological quality of the studies included in the meta-analysis was assessed using the checklist recommended by the Agency for Healthcare Research and Quality. Results The mean CFU/m3 of the conventional HVAC rooms and enhanced HVAC rooms was lower than that of rooms without HVAC systems. Furthermore, the use of the HEPA filter reduced bacteria by 113.13 (95% CI: -197.89, -28.38) CFU/m3 and fungi by 6.53 (95% CI: -10.50, -2.55) CFU/m3. Meanwhile, the indoor bacterial concentration of LAF systems decreased by 40.05 (95% CI: -55.52, -24.58) CFU/m3 compared to that of conventional HVAC systems. Conclusions The HVAC systems in hospitals can effectively remove bioaerosols. Further, the use of HEPA filters is an effective option for areas that are under-ventilated and require additional protection. However, other components of the LAF system other than the HEPA filter are not conducive to removing airborne bacteria and fungi. Limitation of study Although our study analysed the overall trend of indoor bioaerosols, the conclusions cannot be extrapolated to rare, hard-to-culture, and highly pathogenic species, as well as species complexes. These species require specific culture conditions or different sampling requirements. Investigating the effects of HVAC systems on these species via conventional culture counting methods is challenging and further analysis that includes combining molecular identification methods is necessary. Strength of the study Our study was the first meta-analysis to evaluate the effect of HVAC systems on indoor bioaerosols through microbial incubation count. Our study demonstrated that HVAC systems could effectively reduce overall bioaerosol concentrations to maintain better indoor air quality. Moreover, our study provided further evidence that other components of the LAF system other than the HEPA filter are not conducive to removing airborne bacteria and fungi. Practical implication Our research showed that HEPA filters are more effective at removing bioaerosols in HVAC systems than the current LAF system. Therefore, instead of opting for the more costly LAF system, a filter with a higher filtration rate would be a better choice for indoor environments that require higher air quality; this is valuable for operating room construction and maintenance budget allocation.

Bacterial aerosol, particulate matter, and microclimatic parameters in the horse stables in Poland

Keeping horses in good condition requires providing them with living conditions that meet welfare requirements. These animals should be accommodated with suitable space, access to high nutritional fodder and water, and a suitable microclimate in their shelters. When it comes to the environment in the stables, a serious problem is created by particulate matter (PM), which consists of bacteria. PM concentration may be responsible for developing multiple lower respiratory tract diseases in horses, including allergies and recurrent airway obstruction (RAO). In turn, these ailments may lead to decreasing equine physical and mental fitness. Additionally, people who spend time in the stables are exposed to the same harmful factors. The study was conducted in Udórz Stud Farm located in the southern region of Poland. The study was carried out in 2 different types of stables: 3 runners (a type of stable where horses are housed together and occasionally linked up, e.g., for feeding or grooming) and 2 box stables. The research continued for 2 years and the samples were collected in each season. The bioaerosol samples were collected using a six-stage Andersen-Graseby cascade impactor to assess size distribution and concentrations of airborne bacteria. PM concentration was analyzed using the DustTrak™ II Aerosol Monitor 8530, while microclimate parameters were measured using the Kestrel 5000 Weather Meter. There are almost no studies concerning size distribution of airborne bacteria, individual PM fractions, and the impact of everyday handling on the changes in the bioaerosol and PM concentration. This preliminary study provided basic information on this subject. We have revealed a strong correlation between high PM and bacterial aerosol concentrations. Higher contamination levels were recorded in runners, as compared to box stables. The highest bacterial aerosol level was detected in the spring. The analysis of the fractions of the bacterial aerosol in the stables indicated the highest share of ultra-fine fraction (0.65–2.1 µm), while respirable fraction (below 4.7 µm) exceeded 75%. It was established that the concentration of the bacterial aerosol inside the stables was many times higher than outside. It depended significantly on everyday activities undertaken in the stables, like feeding or cleaning. Taking the above into account, a different cleaning system should be developed (a wet cleaning system, with the use of water) and excrement should be removed more frequently.

Indoor Air Quality in New Zealand Office Buildings: Studies of Airborne Bacteria and Fungi

<p>The aim of this thesis was to investigate the levels of indoor airborne bacteria and fungi in fully sealed mechanically ventilated offices in New Zealand. One of the main objectives was to examine the indoor airborne bacterial and fungal levels in Auckland and Wellington offices and to compare the quality of indoor air in offices in both cities. Examining the differences in indoor airborne bacterial and fungal levels between complaint and non-complaint offices as well as comparing those levels with those of similar indoor environments overseas was also one of the main objectives of this thesis. Indoor and outdoor air data used in this thesis were recorded during commercial investigation of 235 offices in Auckland and Wellington by the Institute of Environmental Science and Research (ESR) and Advanced Building Services (ABS). This data included measurements of indoor microclimatic parameters (temperature and relative humidity), indoor and outdoor airborne bacterial and fungal concentrations and indoor carbon dioxide levels. Statistical analyses showed the indoor bacterial levels in Auckland offices were significantly higher than those of Wellington offices. Indoor fungal levels in Auckland offices, on the other hand, were significantly below those of Wellington offices despite the fact that outdoor fungal levels in Auckland were at least three times higher than those of Wellington. No significant differences have been observed between airborne bacterial and fungal levels in complaint and non-complaint offices. Indoor airborne bacterial and fungal levels in New Zealand offices appeared also to be within the levels of those of overseas offices. However, as the bacterial and fungal sampling techniques used by ESR and ABS were different from those used in overseas studies and this can affect airborne bacterial and fungal absolute counts significantly, care is needed in making such comparisons. Finally, an evaluation tool has been developed to overcome the difficulties associated with comparison between indoor airborne fungal levels obtained using different measurements techniques. This tool can be used to establish whether elevated fungal problems exist in an office environment and the likely causes of these problems.</p>

Indoor Air Quality in New Zealand Office Buildings: Studies of Airborne Bacteria and Fungi

<p>The aim of this thesis was to investigate the levels of indoor airborne bacteria and fungi in fully sealed mechanically ventilated offices in New Zealand. One of the main objectives was to examine the indoor airborne bacterial and fungal levels in Auckland and Wellington offices and to compare the quality of indoor air in offices in both cities. Examining the differences in indoor airborne bacterial and fungal levels between complaint and non-complaint offices as well as comparing those levels with those of similar indoor environments overseas was also one of the main objectives of this thesis. Indoor and outdoor air data used in this thesis were recorded during commercial investigation of 235 offices in Auckland and Wellington by the Institute of Environmental Science and Research (ESR) and Advanced Building Services (ABS). This data included measurements of indoor microclimatic parameters (temperature and relative humidity), indoor and outdoor airborne bacterial and fungal concentrations and indoor carbon dioxide levels. Statistical analyses showed the indoor bacterial levels in Auckland offices were significantly higher than those of Wellington offices. Indoor fungal levels in Auckland offices, on the other hand, were significantly below those of Wellington offices despite the fact that outdoor fungal levels in Auckland were at least three times higher than those of Wellington. No significant differences have been observed between airborne bacterial and fungal levels in complaint and non-complaint offices. Indoor airborne bacterial and fungal levels in New Zealand offices appeared also to be within the levels of those of overseas offices. However, as the bacterial and fungal sampling techniques used by ESR and ABS were different from those used in overseas studies and this can affect airborne bacterial and fungal absolute counts significantly, care is needed in making such comparisons. Finally, an evaluation tool has been developed to overcome the difficulties associated with comparison between indoor airborne fungal levels obtained using different measurements techniques. This tool can be used to establish whether elevated fungal problems exist in an office environment and the likely causes of these problems.</p>