Fungal Contamination in Hospital Environments

Objectives.To assess the degree of fungal contamination in hospital environments and to evaluate the ability of air conditioning systems to reduce such contamination.Methods.We monitored airborne microbial concentrations in various environments in 10 hospitals equipped with air conditioning. Sampling was performed with a portable Surface Air System impactor with replicate organism detection and counting plates containing a fungus-selective medium. The total fungal concentration was determined 72-120 hours after sampling. The genera most involved in infection were identified by macroscopic and microscopic observation.Results.The mean concentration of airborne fungi in the set of environments examined was 19 ± 19 colony-forming units (cfu) per cubic meter. Analysis of the fungal concentration in the different types of environments revealed different levels of contamination: the lowest mean values (12 ± 14 cfu/m3) were recorded in operating theaters, and the highest (45 ± 37 cfu/m3) were recorded in kitchens. Analyses revealed statistically significant differences between median values for the various environments. The fungal genus most commonly encountered was Penicillium, which, in kitchens, displayed the highest mean airborne concentration (8 ± 2.4 cfu/m3). The percentage (35%) of Aspergillus documented in the wards was higher than that in any of the other environments monitored.Conclusions.The fungal concentrations recorded in the present study are comparable to those recorded in other studies conducted in hospital environments and are considerably lower than those seen in other indoor environments that are not air conditioned. These findings demonstrate the effectiveness of air-handling systems in reducing fungal contamination.

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Numerical study and optimization of air-conditioning systems grilles used in indoor environments

International Journal of Energy and Environmental Engineering ◽

10.1007/s40095-021-00412-1 ◽

2021 ◽

Author(s):

Luis Angeles-Rodríguez ◽

Cesar Celis

Keyword(s):

Air Conditioning ◽

Numerical Study ◽

Indoor Environments ◽

Air Conditioning Systems

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A dynamic model for human thermal comfort for smart building applications

Proceedings of the Institution of Mechanical Engineers Part I Journal of Systems and Control Engineering ◽

10.1177/0959651819865795 ◽

2019 ◽

Vol 234 (4) ◽

pp. 472-483

Author(s):

Ghezlane Halhoul Merabet ◽

Mohamed Essaaidi ◽

Driss Benhaddou

Keyword(s):

Thermal Comfort ◽

Air Conditioning ◽

Research Work ◽

Comfort Level ◽

Indoor Environments ◽

Air Conditioning System ◽

Human Thermal Comfort ◽

Local Quality ◽

Set Up ◽

Air Conditioning Systems

Thermal comfort is closely related to the evaluation of heating, ventilation, and air conditioning systems. It can be seen as the result of the perception of the occupants of a given environment, and it is the product of the interaction of a number of personal and environmental factors. Otherwise, comfort issues still do not play an important role in the daily operation of commercial buildings. However, in the workplace, local quality effects, in addition to the health, the productivity that has a significant impact on the performance of the activities. In this regard, researchers have conducted, for decades, investigations related to thermal comfort and indoor environments, which includes developing models and indices through experimentations to establish standards to evaluate comfort and factors and set-up parameters for heating, ventilation, and air conditioning systems. However, to our best knowledge, most of the research work reported in the literature deals only with parameters that are not dynamically tracked. This work aims to propose a prototype for comfort measuring through a wireless sensor network and then presenting a model for thermal comfort prediction. The developed model can be used to set up a heating, ventilation, and air conditioning system to meet the expected comfort level. In particular, the obtained results show that there is a strong correlation between users’ comfort and variables such as age, gender, and body mass index as a function of height and weight.

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Exploiting the Advantages of Molecular Tools for the Monitoring of Fungal Indoor Air Contamination: First Detection of Exophiala jeanselmei in Indoor Air of Air-Conditioned Offices

Microorganisms ◽

10.3390/microorganisms7120674 ◽

2019 ◽

Vol 7 (12) ◽

pp. 674

Author(s):

Xavier Libert ◽

Camille Chasseur ◽

Ann Packeu ◽

Fabrice Bureau ◽

Nancy H. Roosens ◽

...

Keyword(s):

Indoor Air ◽

Air Conditioning ◽

Indoor Air Pollution ◽

Airborne Fungi ◽

Interesting Case ◽

Public Health Issue ◽

Molecular Tools ◽

Exophiala Jeanselmei ◽

Monitoring Protocols ◽

Air Conditioning Systems

Today, indoor air pollution is considered a public health issue. Among the impacting pollutants, indoor airborne fungi are increasingly highlighted. Most of the monitoring protocols are culture-based, but these are unable to detect the uncultivable and/or dead fraction or species suppressed by fast-growing fungi, even though this fraction could impact health. Among the contaminants suspected to be part of this fraction, Exophiala jeanselmei is an interesting case study. Known to be pathogenic, this black yeast grows in humid environments such as air-conditioning systems, where it has been previously detected using classical culture-based methods. However, until now, this fungus was never detected in indoor air in contact with these air-conditioning systems. This study shows the first detection of E. jeanselmei in indoor air collected from offices in contact with contaminated air-conditioning reservoirs. While its presence in indoor air could not be demonstrated with culture-based methods, it was found by real-time PCR and massive parallel sequencing. The latter also allowed obtaining a broader view on the fungal diversity in the tested samples. Similar approaches were applied on water samples collected from the conditioning reservoirs to trace the source of contamination. The comparison of results obtained with both methods confirmed that the molecular tools could improve indoor air monitoring, especially of dead and/or uncultivable contaminants or when competition between species could occur.

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Numerical analysis of the methods for reducing the energy use of air-conditioning systems in non-uniform indoor environments

Building and Environment ◽

10.1016/j.buildenv.2019.106442 ◽

2020 ◽

Vol 167 ◽

pp. 106442 ◽

Cited By ~ 4

Author(s):

Chao Liang ◽

Xianting Li ◽

Xiaoliang Shao ◽

Baoming Li

Keyword(s):

Numerical Analysis ◽

Air Conditioning ◽

Energy Use ◽

Indoor Environments ◽

Air Conditioning Systems

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Control Strategies in Multi-Zone Air Conditioning Systems

Energies ◽

10.3390/en12030347 ◽

2019 ◽

Vol 12 (3) ◽

pp. 347 ◽

Cited By ~ 2

Author(s):

Behzad Rismanchi ◽

Juan Zambrano ◽

Bryan Saxby ◽

Ross Tuck ◽

Mark Stenning

Keyword(s):

Air Conditioning ◽

New Technologies ◽

Control Strategies ◽

Efficient Solutions ◽

Indoor Environments ◽

Commercial Building ◽

Thermal Discomfort ◽

Variable Air Volume ◽

Air Volume ◽

Air Conditioning Systems

In a commercial building, a significant amount of energy is used by the ventilation systems to condition the air for the ‎indoor environments to satisfy the required quantity (temperature ‎and humidity) and quality (amount of fresh air). For many years, Variable Air Volume ‎‎(VAV) systems have been considered as the most efficient solutions by balancing the airflow volume based on the demand making them energy efficient when compared with the traditional Constant Air Volume (CAV) systems. However, the setpoints in VAV systems are ‎often misread by the sensors due to stratification and formation of pollutant pockets and ‎responding to design levels that overestimate the real-time demand conditions, which result in ‎waste of energy, thermal discomfort and unhealthy air. In general, VAV devices are expensive, complicated and prone to failures and ‎they are used only in medium and large projects. More recently, new technologies have evolved to solve this issue. In one of the new solutions, VAV motors terminals are replaced with flaps which are simpler and less expensive thus, they can be implemented ‎in a wider range of projects. In systems, balancing and supplying the optimal airflow ‎to reduce the energy consumption while delivering ideal thermal and Indoor Air Quality (IAQ) levels are the ‎main challenges. In this paper, a comparison of the recent technologies with traditional VAV systems is presented to be used as a guild line for researchers and designers in the field of Heating Ventilation Air Conditioning (HVAC)‎.

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Fungal colonization of air-conditioning systems

Archives of Biological Sciences ◽

10.2298/abs0802201l ◽

2008 ◽

Vol 60 (2) ◽

pp. 201-206 ◽

Cited By ~ 6

Author(s):

Milica Ljaljevic-Grbic ◽

Jelena Vukojevic ◽

M. Stupar

Keyword(s):

Aspergillus Fumigatus ◽

Indoor Air ◽

Air Conditioning ◽

Fungal Colonization ◽

Air Conditioner ◽

Volatile Organics ◽

Hospital Environments ◽

Indoor Fungi ◽

Air Conditioning Systems ◽

Human Infections

Fungi have been implicated as quantitatively the most important bioaerosol component of indoor air associated with contaminated air-conditioning systems. rarely, indoor fungi may cause human infections, but more commonly allergenic responses ranging from pneumonitis to asthma-like symptoms. From all air conditioner filters analyzed, 16 fungal taxa were isolated and identified. Aspergillus fumigatus causes more lethal infections worldwide than any other mold. Air-conditioning filters that adsorb moisture and volatile organics appear to provide suitable substrates for fungal colonization. It is important to stress that fungal colonization of air-conditioning systems should not be ignored, especially in hospital environments.

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Can Air-Conditioning Systems Contribute to the Spread of SARS/MERS/COVID-19 Infection? Insights from a Rapid Review of the Literature

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph17176052 ◽

2020 ◽

Vol 17 (17) ◽

pp. 6052 ◽

Cited By ~ 6

Author(s):

Francesco Chirico ◽

Angelo Sacco ◽

Nicola Luigi Bragazzi ◽

Nicola Magnavita

Keyword(s):

Air Conditioning ◽

Far East ◽

Hvac Systems ◽

Rapid Review ◽

Sufficient Evidence ◽

Indoor Environments ◽

Airborne Transmission ◽

International Agencies ◽

Viral Particles ◽

Air Conditioning Systems

The airborne transmission of SARS-CoV-2 is still debated. The aim of this rapid review is to evaluate the COVID-19 risk associated with the presence of air-conditioning systems. Original studies (both observational and experimental researches) written in English and with no limit on time, on the airborne transmission of SARS-CoV, MERS-CoV, and SARS-CoV-2 coronaviruses that were associated with outbreaks, were included. Searches were made on PubMed/MEDLINE, PubMed Central (PMC), Google Scholar databases, and medRxiv. A snowball strategy was adopted to extend the search. Fourteen studies reporting outbreaks of coronavirus infection associated with the air-conditioning systems were included. All studies were carried out in the Far East. In six out the seven studies on SARS, the role of Heating, Ventilation, and Air Conditioning (HVAC) in the outbreak was indirectly proven by the spatial and temporal pattern of cases, or by airflow-dynamics models. In one report on MERS, the contamination of HVAC by viral particles was demonstrated. In four out of the six studies on SARS-CoV-2, the diffusion of viral particles through HVAC was suspected or supported by computer simulation. In conclusion, there is sufficient evidence of the airborne transmission of coronaviruses in previous Asian outbreaks, and this has been taken into account in the guidelines released by organizations and international agencies for controlling the spread of SARS-CoV-2 in indoor environments. However, the technological differences in HVAC systems prevent the generalization of the results on a worldwide basis. The few COVID-19 investigations available do not provide sufficient evidence that the SARS-CoV-2 virus can be transmitted by HVAC systems.

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Assessment of the abundance and diversity of airborne fungi in two different air conditioning systems in Paraíba, Brazil

International Journal of Advanced Engineering Research and Science ◽

10.22161/ijaers.710.39 ◽

2020 ◽

Vol 7 (10) ◽

pp. 342-347

Author(s):

José Soares do Nascimento ◽

Lisiane Martins Volcão ◽

Klebson Cordeiro Costa ◽

Marília Gabriela dos Santos Cavalcanti ◽

Bruno Henrique Andrade Galvão

Keyword(s):

Air Conditioning ◽

Airborne Fungi ◽

Abundance And Diversity ◽

Air Conditioning Systems

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Air-Conditioning and the Transmission of COVID-19 in Indoor Environment

Environmental Management and Sustainable Development ◽

10.5296/emsd.v10i3.18461 ◽

2021 ◽

Vol 10 (3) ◽

pp. 1

Author(s):

Tosin T. Oye ◽

Naren Gupta ◽

Keng Goh ◽

Toyosi K. Oye

Keyword(s):

Air Conditioning ◽

Indoor Environment ◽

Respiratory Infections ◽

Indoor Environments ◽

Infectious Dose ◽

Air Conditioning Systems ◽

Droplet Nuclei ◽

Respiratory Droplets

Substandard ventilation in restricted air-conditioning indoor places is allied with upsurge in the respiratory infections’ transmission. There have been several COVID-19 spread occurrences connected with indoor environment, together with a few from pre-symptomatic situations. Ventilation role in averting coronavirus transmission is not precise (i.e., through inhibiting transmission of an infectious dose to susceptible individuals or preventing the spreading of contagious particles to lessen the risk of transmission). SARS-CoV-2 is believed to be mainly spread through significant respiratory droplets, nevertheless, a growing amount of epidemic information associate aerosol role in the epidemics of coronavirus. Aerosols comprise of droplet nuclei and little droplets which stay in the air for longer than significant droplets. Recent studies show that coronavirus particles can stay transmissible on numerous substances, including aerosols within the indoor environments, as well as the contagion period contingent on humidity and temperature. Thus far, COVID-19 transmission via air-conditioning systems is unclear, but it is considered possible.

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