Indoor/Outdoor airborne microbiome characteristics in residential areas across four seasons and its indoor purification.

Bioaerosols are more likely to accumulate in the residential environment, and long-term inhalation may lead to a variety of diseases and allergies. Here, we studied the distribution, influencing factors and diffusion characteristics of indoor and outdoor microbiota pollution in six residential buildings in Guangzhou, southern China over a period of one year. The results showed that the particle sizes of bioaerosol were mainly in the range of inhalable particle size (<4.7 µm) with a small difference among four seasons (74.61 % ± 2.17 %). The microbial communities showed obvious seasonal differences with high abundance in summer, but no obvious geographical differences. Among them, the bacteria were more abundant than the fungi. The dominant microbes in indoor and outdoor environments were similar, with Anoxybacillu, Brevibacillus and Acinetobacter as the dominant bacteria, and Cladosporium, Penicillium and Alternaria as the dominant fungi. The airborne microbiomes were more sensitive to temperature and particulate matter (PM2.5, PM10) concentrations. Based on the Sloan neutral model, bacteria were more prone to random diffusion than fungi, and the airborne microbiome can be randomly distributed in indoor and outdoor environments and between the two environments in each season. Bioaerosol in indoor was mainly from outdoor. The health risk evaluation showed that the indoor inhalation risks were higher than those outdoor. The air purifier had a better removal efficiency on 1.1-4.7 µm microorganisms, and the removal efficiency on Gram-negative bacteria was better than that on Gram-positive bacteria. This study is of great significance for the risk assessment and control of residential indoor bioaerosol exposure.

Airborne pollen exposure and risk of hospital admission for allergic rhinitis in Beijing: A time-stratified case-crossover study.

BACKGROUND: Airborne pollen is a crucial risk factor in allergic rhinitis (AR). The severity of AR symptoms can vary based on pollen type and concentration. This study aimed to estimate the association between exposure to different pollen types and AR risk. METHODS: We obtained data from patients admitted to the Beijing Tongren Hospital for AR, and data on pollen concentration, meteorological factors, and fine particulate matter (PM2.5) from 13 districts in Beijing from 2016 to 2019. We used a time-stratified case-crossover study design and calculated odds ratios (ORs) related to the risk of AR associated with a 10 grain/1000 mm2 increase in total pollen concentrations for specific pollen types. A stratified analysis was conducted to assess whether the associations were varied by age and sex. RESULTS: The OR of AR associated with a 10 grain/1000 mm2 increase in the 7-day average pollen concentration was 1.014 (95% CI: 1.014, 1.015), 1.076 (95% CI: 1.070, 1.082), 1.024 (95% CI: 1.023, 1.025), 1.042 (95% CI: 1.039, 1.045), 1.142 (95% CI: 1.137, 1.147), 1.092 (95% CI: 1.088, 1.097), 1.046 (95% CI: 1.035, 1.058), and 1.026 (95% CI: 1.024, 1.028) for total pollen, Ulmus, Cupressaceae, Populus, Fraxinus, Pinus, Betula, and Artemisia, respectively. Both tree pollen (Ulmus, Cupressaceae, Populus, Fraxinus, Betula, and Pinus) and weed pollen (Artemisia, Chenopodium, and Humulus) were correlated with an increased risk of AR. These associations remained consistent across distinct subgroups defined by both age and sex. CONCLUSION: Exposure to pollen from trees and weeds might be associated with an increased risk of AR. This research provides valuable scientific support for both clinical practitioners and patients with AR regarding the hazards of pollen exposure.

Assessing the potential spray drift of a six-rotor unmanned aerial vehicle sprayer using a test bench and airborne drift collectors under low wind velocities: impact of atomization characteristics and application parameters.

BACKGROUND: The unmanned aerial spraying systems (UASS) have gained widespread use for plant protection in recent years. However, spray drift from UASS is a major concern when controlling weeds over large areas and warrants a thorough investigation. This study examined the atomization characteristics of the herbicide florpyrauxifen-benzyl under downwash airflow using a UASS spray test platform. Potential spray drift was assessed using a test bench (TB) and airborne drift collectors (ADCs) in the field under low wind speeds (<1 m s-1). RESULTS: Atomization characteristics were significantly affected by the spray liquid, adjuvant, nozzle type and spray pressure. The addition of an adjuvant reduced the liquid sheet length, improved physicochemical properties and increased droplet size under the downwash airflow field. Drift evaluation in the field using the TB revealed that sediment spray drift predominantly occurred from the middle to the entire length of the device when fine-to-medium droplets were produced after the sprayer passed. ADC assessment found that higher flight altitudes and finer droplets resulted in higher drift values, whereas the addition of an adjuvant and the use of an air-induction nozzle reduced drift <3 m aboveground. CONCLUSION: The combination of using TB in the target area and ADCs in the off-target area as an alternative method to determine residual droplets in the current airflow provided valuable insights into airborne drift assessment for UASS. © 2024 Society of Chemical Industry.

A novel approach to managing facility airborne diseases: suppressing air pathogens with smoke aerosols generated from fungicide phase transition.

BACKGROUND: Environmental microorganisms are major contributors to the development and spread of disease. Chemical disinfection can inhibit pathogens and play a preventive role against diseases. In agriculture, prolonging the floating time of chemical pesticides in the air has a positive effect on the control of airborne diseases. However, the interaction of chemical pesticides with airborne pathogens is not yet known. RESULTS: Here, triazole fungicide was transformed into stable smoke aerosols in order to assess the feasibility of employing phase transition release pesticides for air disinfection. The phase transition had a minimal impact on hexaconazole (Hexa) and myclobutanil (Mycl), with their smoke formation rates remaining consistently >90%. In microscopic morphology, triadimenol (Tria) and epoxiconazole (Epox) are solid, and tebuconazole (Tebu), Hexa, Mycl and difenoconazole (Dife) are liquid. Liquid smoke has advantages over solid smoke in the inhibition of environmental pathogens. The floatability and spatial distribution of fungicide aerosol were optimized by the combination of smoke particles with different properties, so that the fungicide aerosol could meet the conditions of practical application. In practical applications, smoke exhibits a gentler deposition process at the target interface compared to spray, along with a more homogeneous distribution of fungicides. Moreover, fungicide smoke demonstrates superior control efficacy and leaves behind lower residual amounts on fruit. CONCLUSION: In conclusion, the implementation of fungicide phase transition as a smoke aerosol offers a viable approach to effectively suppress pathogen aerosols and enhance the control of airborne diseases. © 2024 Society of Chemical Industry.

Evaluation of trend and mortality pattern of communicable diseases in a teaching institution in Kerala.

Context: Even in this era of epidemiologic transition communicable disease is still a major public health problem. Surveillance and timely prevention and control activities are the key to the reduction of morbidity and mortality of communicable diseases. Identifying the trend in communicable diseases and pattern of mortality for a period of ten years will be an insight into the ongoing surveillance. Aim: In this study we have analysed data from 2013 to 2022 to evaluate the trend and mortality pattern of communicable diseases in a teaching institution in Kerala. Settings and Design: A retrospective record-based cross-sectional study conducted at the Department of Community Medicine, Government Medical College, Kottayam. Methods and Material: All confirmed communicable disease cases reported from 2013 to 2022 were included in this study except COVID-19-positive cases. The communicable diseases were grouped as: airborne, waterborne, vector-borne, zoonosis, bloodborne diseases and others. SPSS version 20.0 software, Microsoft Word, and Excel were used in data handling and analysis. Results: Total cases reported were 48124. The majority of the morbidity was due to airborne diseases (17585,37%) followed by waterborne diseases (6381, 13%). The total number of deaths reported was 1842. Airborne and zoonotic diseases together accounted for more than 50% of the mortality. Case fatality rate of zoonosis (20.2%) was the highest followed by bloodborne diseases (10.2%). Conclusions: Communicable diseases still continue as a public health problem contributing to morbidity and mortality. Airborne diseases and zoonotic diseases constitute the maximum mortality.

Noviherbaspirillum album sp. nov., an airborne bacteria isolated from an urban area of Beijing, China.

A Gram-negative, ellipsoidal to short-rod-shaped, motile bacterium was isolated from Beijing's urban air. The isolate exhibited the closest kinship with Noviherbaspirillum aerium 122213-3T, exhibiting 98.4 % 16S rRNA gene sequence similarity. Phylogenetic analyses based on 16S rRNA gene sequences and genomes showed that it clustered closely with N. aerium 122213-3T, thus forming a distinct phylogenetic lineage within the genus Noviherbaspirillum. The average nucleotide identity and digital DNA-DNA hybridization values between strain I16B-00201T and N. aerium 122213-3T were 84.6 and 29.4 %, respectively. The respiratory ubiquinone was ubiquinone 8. The major fatty acids (>10 %) were summed feature 3 (C16:1ω6c/C16:1ω7c, 43.3 %), summed feature 8 (C18:1ω7c/C18:1ω6c, 15.9 %) and C12:0 (11.0 %). The polyamine profile showed putrescine as the predominant compound. The polar lipid profile consisted of diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylcholine, unknown lipids and unknown phosphatidylaminolipids. The phenotypic, phylogenetic and chemotaxonomic results consistently supported that strain I16B-00201T represented a novel species of the genus Noviherbaspirillum, for which the name Noviherbaspirillum album sp. nov. is proposed, with I16B-00201T (=CPCC 100848T=KCTC 52095T) designated as the type strain. Its DNA G+C content is 59.4 mol%. Pan-genome analysis indicated that some Noviherbaspirillum species possess diverse nitrogen and aromatic compound metabolism pathways, suggesting their potential value in pollutant treatment.

Radiocaesium in mosses from the Kopacki rit Nature Park in Croatia: searching for undeclared releases from nuclear facilities in war-torn Ukraine.

The invasion of Ukraine and military operations around Ukrainian nuclear power plants and other nuclear facilities have prompted us to search for radiocaesium in mosses from the Kopacki Rit Nature Park in Croatia, since mosses are known bioindicators of airborne radioactive pollution, and Kopacki Rit is a known low radiocaesium background area. Sampling was finished in August 2023, and our analysis found no elevated radiocaesium levels. Kopacki Rit therefore remains a suitable place for future detection of anthropogenic radioactive pollutants.

A Simulation Study to Reveal the Epidemiology and Aerosol Transmission Characteristics of Botrytis cinerea in Grape Greenhouses.

Most previously studies had considered that plant fungal disease spread widely and quickly by airborne fungi spore. However, little is known about the release dynamics, aerodynamic diameter, and pathogenicity threshold of fungi spore in air of the greenhouse environment. Grape gray mold is caused by Botrytis cinerea; the disease spreads in greenhouses by spores in the air and the spore attaches to the leaf and infects plant through the orifice. In this study, 120 µmol/L propidium monoazide (PMA) were suitable for treatment and quantitation viable spore by quantitative real-time PCR, with a limit detection of 8 spores/mL in spore suspension. In total, 93 strains of B. cinerea with high pathogenicity were isolated and identified from the air samples of grapevines greenhouses by a portable sampler. The particle size of B. cinerea aerosol ranged predominately from 0.65-3.3 µm, accounting for 71.77% of the total amount. The B. cinerea spore aerosols were infective to healthy grape plants, with the lowest concentration that could cause disease being 42 spores/m3. Botrytis cinerea spores collected form six greenhouse in Shandong Province were quantified by PMA-qPCR, with a higher concentration (1182.89 spores/m3) in May and June and a lower concentration in July and August (6.30 spores/m3). This study suggested that spore dispersal in aerosol is an important route for the epidemiology of plant fungal disease, and these data will contribute to the development of new strategies for the effective alleviation and control of plant diseases.

Laboratory studies on the infectivity of human respiratory viruses: Experimental conditions, detections, and resistance to the atmospheric environment.

The environmental stability of infectious viruses in the laboratory setting is crucial to the transmission potential of human respiratory viruses. Different experimental techniques or conditions used in studies over the past decades have led to diverse understandings and predictions for the stability of viral infectivity in the atmospheric environment. In this paper, we review the current knowledge on the effect of simulated atmospheric conditions on the infectivity of respiratory viruses, mainly focusing on influenza viruses and coronaviruses, including severe acute respiratory syndrome coronavirus 2 and Middle East respiratory syndrome coronavirus. First, we summarize the impact of the experimental conditions on viral stability; these involve the methods of viral aerosol generation, storage during aging and collection, the virus types and strains, the suspension matrixes, the initial inoculum volumes and concentrations, and the drying process. Second, we summarize and discuss the detection methods of viral infectivity and their disadvantages. Finally, we integrate the results from the reviewed studies to obtain an overall understanding of the effects of atmospheric environmental conditions on the decay of infectious viruses, especially aerosolized viruses. Overall, this review highlights the knowledge gaps in predicting the ability of viruses to maintain infectivity during airborne transmission.

Recent progress in online detection methods of bioaerosols.

The aerosol transmission of coronavirus disease in 2019, along with the spread of other respiratory diseases, caused significant loss of life and property; it impressed upon us the importance of real-time bioaerosol detection. The complexity, diversity, and large spatiotemporal variability of bioaerosols and their external/internal mixing with abiotic components pose challenges for effective online bioaerosol monitoring. Traditional methods focus on directly capturing bioaerosols before subsequent time-consuming laboratory analysis such as culture-based methods, preventing the high-resolution time-based characteristics necessary for an online approach. Through a comprehensive literature assessment, this review highlights and discusses the most commonly used real-time bioaerosol monitoring techniques and the associated commercially available monitors. Methods applied in online bioaerosol monitoring, including adenosine triphosphate bioluminescence, laser/light-induced fluorescence spectroscopy, Raman spectroscopy, and bioaerosol mass spectrometry are summarized. The working principles, characteristics, sensitivities, and efficiencies of these real-time detection methods are compared to understand their responses to known particle types and to contrast their differences. Approaches developed to analyze the substantial data sets obtained by these instruments and to overcome the limitations of current real-time bioaerosol monitoring technologies are also introduced. Finally, an outlook is proposed for future instrumentation indicating a need for highly revolutionized bioaerosol detection technologies.

Global warming contributes to reduction in the intensity of Artemisia pollen seasons in Lublin, central-eastern Poland.

INTRODUCTION AND OBJECTIVE: Species of the genus Artemisia (Asteraceae) are weeds and ruderal plants growing in northern temperate regions of the world. Many of them are used in medicine and the cosmetic industry and for culinary purposes. Pollen grains of plants of this genus contain the most important aeroallergens. MATERIAL AND METHODS: An aerobiological study conducted with the volumetric method in Lublin in 2001-2022. Trend lines for the season parameters were established. Spearman's correlation and stepwise regression analyses were carried out to determine relationships between various parameters of the pollen season and meteorological factors. PCA analysis was also carried out to visually compare the pollen seasons. RESULTS: In Lublin, central-eastern Poland, the Artemisia pollen season lasted on average from the second ten days of July to the end of August, with its beginning depending on the temperature in April and May. The highest pollen concentrations were mainly recorded in the first half of August and were largely dependent on the mean temperature in June and July. The second peak in the pollen season recorded in September was associated with the presence of Artemisia annua pollen. Intense sunshine in June and the higher temperatures in June and July resulted in significant reduction in the Artemisia annual pollen sum (by 65%) over 22 years. Artemisia vulgaris is abundant in the Lublin region and contributes substantially to the amount of Artemisia pollen in the aeroplankton. CONCLUSIONS: The downward trend in the amount of Artemisia pollen was a result of the increase in temperatures observed in the summer months, and the declining rainfall rates. The global warming effect is extremely unfavourable for plants of Artemisia vulgaris, as they require moist soil substrates for growth.

Personal exposure to airborne organic pollutants and lung function changes among healthy older adults.

Epidemiological evidence on the impact of airborne organic pollutants on lung function among the elderly is limited, and their underlying biological mechanisms remain largely unexplored. Herein, a longitudinal panel study was conducted in Jinan, Shandong Province, China, involving 76 healthy older adults monitored over a span of five months repetitively. We systematically evaluated personal exposure to a diverse range of airborne organic pollutants using a wearable passive sampler and their effects on lung function. Participants' pulmonary function indicators were assessed, complemented by comprehensive multi-omics analyses of blood and urine samples. Leveraging the power of interaction analysis, causal inference test (CIT), and integrative pathway analysis (IPA), we explored intricate relationships between specific organic pollutants, biomolecules, and lung function deterioration, elucidating the biological mechanisms underpinning the adverse impacts of these pollutants. We observed that bis (2-chloro-1-methylethyl) ether (BCIE) was significantly associated with negative changes in the forced vital capacity (FVC), with glycerolipids mitigating this adverse effect. Additionally, 31 canonical pathways [e.g., high mobility group box 1 (HMGB1) signaling, phosphatidylinositol 3-kinase (PI3K)/AKT pathway, epithelial mesenchymal transition, and heme and nicotinamide adenine dinucleotide (NAD) biosynthesis] were identified as potential mechanisms. These findings may hold significant implications for developing effective strategies to prevent and mitigate respiratory health risks arising from exposure to such airborne pollutants. However, due to certain limitations of the study, our results should be interpreted with caution.

Development of a vibration-damping, sound-insulating, and heat-insulating porous sphere foam system and its application in green buildings.

With the development of green buildings, people pay more attention to the quality of the indoor sound environment. The air sound insulation performance of floors and exterior walls plays a key role in today's green buildings. The thermal performance of the enclosure structure's floor and exterior wall heat transfer resistance is an important factor in reducing building carbon emissions in green buildings. The aim of this paper is to study the efficiency of the acoustic and thermal insulation of a foaming system with porous carbon balls and the combination of different structural ways of construction boards and external walls. The acoustic and thermal parameters of different sound insulation and thermal insulation systems designed with porous carbon sphere foam and inserted into the floors and exterior walls are compared to highlight the optimal structure. The theoretical and experimental tests showed that to improve the sound insulation performance of the floor, a sound insulation system needs to be placed on the surface of the floor in contact with the impact object and inlaid in the vertical gap in contact with the floor and the wall. Furthermore, it has been determined that the surface of the foam particle acoustic ball with micropores has good sound absorption performance. Finally, the high-quality building thermal insulation material with low thermal conductivity in any combination with the floor slabs and the external wall structure improves the thermal insulation performance.

Disturbance Observation and Suppression in an Airborne Electro-Optical Stabilized Platform Based on a Generalized High-Order Extended State Observer.

Active disturbance rejection control (ADRC) is widely used in airborne optoelectronic stabilization platforms due to its minimal reliance on the mathematical model of the controlled object. The extended state observer (ESO) is the core of ADRC, which treats internal parameter variations and external disturbances as total disturbances, observes the disturbances as extended states, and then compensates them into the control loop to eliminate their effects. However, the ESO can only achieve a precise estimation of constant or slowly varying disturbances. When the disturbance is periodically changing, satisfactory results cannot be obtained. In this paper, a generalized high-order extended state observer (GHOESO) is proposed to achieve the precise estimation of known frequency sinusoidal disturbance signals and improve disturbance suppression levels. Through numerical simulations, a traditional ESO and GHOESO are compared in terms of disturbance observation capability and disturbance suppression ability for single and compound disturbances based on our prior knowledge of disturbance frequency. The effectiveness of the proposed GHOESO method is verified. Finally, the algorithm is applied to an airborne optoelectronic stabilization platform for a 1°/1 Hz swing experiment on a space hexapod swing table. The experimental results demonstrate the superiority of the GHOESO proposed in this paper.

Quantitative evaluation of anthropogenic sources and health risks of rare earth elements in airborne particulate matter.

Rare earth elements (REEs) have emerged as contaminants in airborne particulate matter (PM); however, their anthropogenic sources remain poorly quantified, and associated health risks are unknown. This study investigates the REE distribution across eight sizes of airborne PM during July and December in Qingdao, a major Chinese port city. Our results reveal a single coarse-mode distribution with REE concentrations. In contrast, fine PM (size: 0.43-2.1 µm) exhibits notable enrichment of La and Ce compared to Al and other REEs. This study traces La and Ce enrichment to fluid catalytic cracking catalysts (FCCC)-related sources, including refinery and ship emissions, by comparing the REE fractionation in samples with potential sources. We quantify the contributions from FCCC-related sources to La (July: 33.6 % ± 3.2 %, Dec.: 46.4 % ± 5.2 %) and Ce (July: 16.5 % ± 14.3 %, Dec.: 30.3 % ± 12.2 %) by comparing measured concentrations with predictions derived from neighboring REEs, a method previously used exclusively in aquatic systems. For the first time, supply ratios of refinery and ship to FCCC-related La are calculated using a two-component mixing model based on the [La]FCCC/[V]anth, revealing the dominance of refinery emissions (July: 97.3 % ± 0.6 %, Dec.: 99.6 % ± 0.1 %). Furthermore, a global review of La and Ce anomalies that integrates published REE data with our findings reveals a widespread distribution of positive anomalies. The significantly positive correlation between La and Ce anomalies underscores FCCC-related emissions as a global source in fine PM, contributing 0-92 % (mean: 35 % ± 33 %) for La and 0-72 % (mean: 21 % ± 24 %) for Ce. Although the non-carcinogenic health risks of Ce are generally low globally, concerns should be raised in areas near source emissions, where Ce health risks sharply increased along with its concentrations. There is urgently need to establish a threshold value for La, owing to its global enrichment. This study provides novel insights into the sources and health implications of REEs in airborne PM.

The Oxidative Potential of Airborne Particulate Matter Research Trends, Challenges, and Future Perspectives-Insights from a Bibliometric Analysis and Scoping Review.

This study is a comprehensive analysis of the oxidative potential (OP) of particulate matter (PM) and its environmental and health impacts. The researchers conducted a bibliometric analysis and scoping review, screening 569 articles and selecting 368 for further analysis. The study found that OP is an emerging field of study, with a notable increase in the number of publications in the 2010s compared to the early 2000s. The research is primarily published in eight journals and is concentrated in a few academic and university-based institutions. The study identified key research hotspots for OP-PM, emphasizing the importance of capacity building, interdisciplinary collaboration, understanding emission sources and atmospheric processes, and the impacts of PM and its OP. The study highlighted the need to consider the effects of climate change on OP-PM and the regulatory framework for PM research. The findings of this study will contribute to a better understanding of PM and its consequences, including human exposure and its effects. It will also inform strategies for managing air quality and protecting public health. Overall, this study provides valuable insights into the field of OP-PM research and highlights the need for continued research and collaboration to address the environmental and health impacts of PM.

An Engineering Alternative to Lockdown During COVID-19 and Other Airborne Infectious Disease Pandemics: Feasibility Study.

BACKGROUND: Now and in the future, airborne diseases such as COVID-19 could become uncontrollable and lead the world into lockdowns. Finding alternatives to lockdowns, which limit individual freedoms and cause enormous economic losses, is critical. OBJECTIVE: The purpose of this study was to assess the feasibility of achieving a society or a nation that does not require lockdown during a pandemic due to airborne infectious diseases through the mass production and distribution of high-performance, low-cost, and comfortable powered air purifying respirators (PAPRs). METHODS: The feasibility of a social system using PAPR as an alternative to lockdown was examined from the following perspectives: first, what PAPRs can do as an alternative to lockdown; second, how to operate a social system utilizing PAPR; third, directions of improvement of PAPR as an alternative to lockdown; and finally, balancing between efficiency of infection control and personal freedom through the use of Internet of Things (IoT). RESULTS: PAPR was shown to be a possible alternative to lockdown through the reduction of airborne and droplet transmissions and through a temporary reduction of infection probability per contact. A social system in which individual constraints imposed by lockdown are replaced by PAPRs was proposed, and an example of its operation is presented in this paper. For example, the government determines the type and intensity of the lockdown and activates it. At that time, the government will also indicate how PAPR can be substituted for the different activity and movement restrictions imposed during a lockdown, for example, a curfew order may be replaced with the permission to go outside if wearing a PAPR. The following 7 points were raised as directions for improvement of PAPR as an alternative method to lockdown: flow optimization, precise differential pressure control, design improvement, maintenance method, variation development such as booth type, information terminal function, and performance evaluation method. In order to achieve the effectiveness and efficiency in controlling the spread of infection and the individual freedom at a high level in a social system that uses PAPRs as an alternative to lockdown, it was considered effective to develop a PAPR wearing rate network management system utilizing IoT. CONCLUSIONS: This study shows that using PAPR with infection control ability and with less economic and social damage as an alternative to nationwide lockdown is possible during a pandemic due to airborne infectious diseases. Further, the efficiency of the government's infection control and each citizen's freedom can be balanced by using the PAPR wearing rate network management system utilizing an IoT system.

Assessment of chlorine and hydrogen peroxide on airborne bacteria: Disinfection efficiency and induction of antibiotic resistance.

Airborne pathogens severely threaten public health worldwide. Air disinfection is essential to ensure public health. However, excessive use of disinfectants may endanger environmental and ecological security due to the residual disinfectants and their by-products. This study systematically evaluated disinfection efficiency, induction of multidrug resistance, and the underlying mechanisms of disinfectants (NaClO and H2O2) on airborne bacteria. The results showed that airborne bacteria were effectively inactivated by atomized NaClO (>160 µg/L) and H2O2 (>320 µg/L) after 15 min. However, some bacteria still survived after disinfection by atomized NaClO (0-80 µg/L) and H2O2 (0-160 µg/L), and they exhibited significant increases in antibiotic resistance. The whole-genome sequencing of the resistant bacteria revealed distinct mutations that were responsible for both antibiotic resistance and virulence. This study also provided evidences and insights into possible mechanisms underlying the induction of antibiotic resistance by air disinfection, which involved intracellular reactive oxygen species formation, oxidative stress responses, alterations in bacterial membranes, activation of efflux pumps, and the thickening of biofilms. The present results also shed light on the role of air disinfection in inducing antibiotic resistance, which could be a crucial factor contributing to the global spread of antibiotic resistance through the air.

Operating Room Airborne Microbial Load: Nonscrubbed Staff Apparel Matters.

BACKGROUND: Infection is a leading cause of total joint arthroplasty failure. In previous studies, we found correlations between the level of contamination, concentrations of airborne particles, and the number of staff present. In this study, we focused on the apparel of nonscrubbed operating room (OR) staff to elucidate their contribution to the airborne microbial load. METHODS: We compared hospital-laundered scrubs to disposable coveralls using 2 methods. (1) Participants entered an isolation chamber with a controlled environment and completed tasks for 1 hour wearing both the approved and alternative OR attire. Settle plates collected viable contaminants that were shed by the participants during testing. (2) Lab members conducted standardized maneuvers in a functional OR that simulated typical movements of the nurse, anesthesiologist, implant representative, and entering/exiting staff. An airborne particle counter and settle plates were positioned throughout the OR. After 1 hour, the staff changed apparel and repeated the test. Each session of both phases consisted of 2 tests by the same individuals on the same day. RESULTS: There was approximately a 10-fold difference in the settlement rate of viable particles between groups when employing the isolation chamber. The settle rate for scrubs was 5,519 ± 1,381 colony forming units (CFUs)/m2/h, while the settle rate for coveralls was 505 ± 55 CFUs/m2/h (P = .008). During testing in the OR, 218.7 ± 35 CFUs/m2/h were captured for scrubs, compared with 50.5 ± 13 CFUs/m2/h for the coverall (P < .01). The concentration of airborne particles collected for scrubs was 4,952.1 ± 495 particles/m3 and 1,065 ± 53 particles/m3 for the coveralls (P < .01). This was a 77% and 79% reduction for both measures, respectively. CONCLUSIONS: The open nature of standard scrubs allows contaminated particles to escape into the OR environment, whereas the one-piece design of the coveralls restricts pathways of escape. The results of this study may be helpful when developing hospital infection prevention policies.