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.

Airflow Characteristics in Aeromedical Aircraft: Considerations During COVID-19.

OBJECTIVE: The aeromedical transport of coronavirus patients presents risks to clinicians and aircrew. Patient positioning and physical barriers may provide additional protection during flight. This paper describes airflow testing undertaken on fixed wing and rotary wing aeromedical aircraft. METHODS: Airflow testing was undertaken on a stationary Hawker Beechcraft B200C and Leonardo Augusta Westland 139. Airflow was simulated using a Trainer 101 (MSS Professional A/S, Odense Sø, Syddanmark, Denmark) Smoke machine. Different cabin configurations were used along with variations in heating, cooling, and ventilation systems. RESULTS: For the Hawker Beechcraft B200C, smoke generated within the forward section of the cabin was observed to fill the cabin to a fluid boundary located in-line with the forward edge of the cargo door. With the curtain closed, smoke was only observed to enter the cockpit in very small quantities. For the Leonardo AW139, smoke generated within the cabin was observed to expand to fill the cabin evenly before dissipating. With the curtain closed, smoke was observed to enter the cockpit only in small quantities CONCLUSION: The use of physical barriers in fixed wing and rotary wing aeromedical aircraft provides some protection to aircrew. Optimal positioning of the patient is on the aft stretcher on the Beechcraft B200C and on a laterally orientated stretcher on the AW139. The results provide a baseline for further investigation into methods to protect aircrew during the coronavirus pandemic.

SARS-CoV-2 indoor contamination: considerations on anti-COVID-19 management of ventilation systems, and finishing materials in healthcare facilities.

Abstract: Many of the devastating pandemics and outbreaks of last centuries have been caused by enveloped viruses. The recent pandemic of Coronavirus disease 2019 (COVID-19) has seriously endangered the global health system. In particular, hospitals have had to deal with a frequency in the emergency room and a request for beds for infectious diseases never faced in the last decades. It is well-known that hospitals are environments with a high infectious risk. Environmental control of indoor air and surfaces becomes an important means of limiting the spread of SARS-CoV-2. In particular, to preserve an adequate indoor microbiological quality, an important non-pharmacological strategy is represented by Heating, Ventilation and Air Conditioning (HVAC) systems and finishing materials. Starting from the SARS-CoV-2 transmission routes, the paper investigates the hospital risk analysis and management, the indoor air quality and determination of microbial load, surface management and strategies in cleaning activities, HVAC systems' management and filters' efficiency. In conclusion, the paper suggests some strategies of interventions and best practices to be taken into considerations for the next steps in design and management.

[Interpretation for the group standards in technical specification for health risk investigation of central air conditioning ventilation system during coronavirus disease 2019 epidemic].

The central air conditioning ventilation system plays an important role in the air circulation of buildings such as centralized isolation medical observation points and general public buildings. In order to meet the requirements of COVID-19 epidemic prevention and control, Beijing Preventive Medicine Association organized Beijing CDC and other professional institutes to write up the group standard entitled "Technical specification for health risk investigation of central air conditioning ventilation system during the COVID-19 epidemic (T/BPMA 0006-2020)" . According to the particularity of central air conditioning ventilation system risk control during the outbreak of similar respiratory infectious diseases, based on current laws and regulations and the principle of scientific, practical, consistency and normative, 8 key points of risk investigations were summarized, which were the location of fresh air outlet, air conditioning mode, air return mode, air system, air distribution, fresh air volume, exhaust and air conditioner components. The contents, process, method, data analysis and conclusion of the investigation implementation were also defined and unified. It could standardize and guide institutions such as disease control and health supervision to carry out relevant risk managements, and provided solutions and technical supports for such major public health emergencies in city operations.

Hospital care in Departments defined as COVID-free: A proposal for a safe hospitalization protecting healthcare professionals and patients not affected by COVID-19.

The COVID-19 pandemic influenced the normal course of clinical practice leading to significant delays in the delivery of healthcare services for patients non affected by COVID-19. In the near future, it will be crucial to identify facilities capable of providing health care in compliance with the safety of healthcare professionals, administrative staff and patients. All the staff involved in the project of a Covid-free hospital should be subjected to a diagnostic swab for COVID-19 before the beginning of healthcare activity and then periodically in order to avoid the risk of contamination of patients during the process of care. The modifications of various activities involved in the process of care are described: outpatient care, reception of inpatients, inpatient ward and operating room. For outpatient care, modality of appointment procedure, characteristics of waiting room and personal protective equipment (PPE) for healthcare professionals and administrative staff are presented. Reception of inpatients shall be conditional on a negative swab for COVID-19 obtained with a drive-in procedure. The management of the operating room represents the most crucial step of the patient's care process. The surgical team should be restricted and monitored with periodic swabs; surgical procedures should be performed by experienced surgeons according to standard procedures; surgical training experimental treatments and research protocols should be suspended. Adequate personal protective equipment and measures to reduce aerosolization in the operating room (closed circuits, continuous cycle insufflators, fume extraction) should be adopted. Prevention of possible transmission of the virus during procedures in open, laparoscopic and endoscopic surgery is to use a multi-tactic approach, which includes correct filtration and ventilation of the operating room, the use of appropriate PPE (FFP3 plus surgical mask and protective visor for all the staff working in the operating room) and smoke evacuation devices with a suction and filter system.   on behalf of the UrOP Executive Committee Giuseppe Ludovico, Angelo Cafarelli, Ottavio De Cobelli, Ferdinando De Marco, Giovanni Ferrari, Stefano Pecoraro, Angelo Porreca, Domenico Tuzzolo.

Conversion of positive-pressure cardiac catheterization and electrophysiology laboratories to a novel 2-zone negative-pressure system during COVID-19 pandemic.

During coronavirus disease-2019 (COVID-19) pandemic, there continues to be a need to utilize cardiac catheterization and electrophysiology laboratories for emergent and urgent procedures. Per infection prevention guidelines and hospital codes, catheterization and electrophysiology laboratories are usually built as positive-pressure ventilation rooms to minimize the infection risk. However, patients with highly transmissible airborne diseases such as COVID-19 are best caredfor in negative ventilation rooms to minimize the risk of transmission. From a mechanical and engineering perspective, positive-pressure ventilation rooms cannot be readily converted to negative-pressure ventilation rooms. In this report, we describe a novel, quick, readily implantable, and resource-friendly approach on how to secure air quality in catheterization and electrophysiology laboratories by converting a positive-pressure ventilation room to a two-zone negative ventilation system to minimize the risk of transmission.

Rapid expansion of temporary, reliable airborne-infection isolation rooms with negative air machines for critical COVID-19 patients.

More airborne-infection isolation rooms are needed in centers that treat severely affected coronavirus 2019 patients. Wards and rooms must be carefully checked to ensure an ample supply of medical air and oxygen. Anterooms adjacent to airborne-infection isolation rooms are required to maintain pressure differentials and provide an area for donning/doffing or disinfecting medical equipment.

Airborne route and bad use of ventilation systems as non-negligible factors in SARS-CoV-2 transmission.

The world is facing a pandemic of unseen proportions caused by a corona virus named SARS-CoV-2 with unprecedent worldwide measures being taken to tackle its contagion. Person-to-person transmission is accepted but WHO only considers aerosol transmission when procedures or support treatments that produce aerosol are performed. Transmission mechanisms are not fully understood and there is evidence for an airborne route to be considered, as the virus remains viable in aerosols for at least 3 h and that mask usage was the best intervention to prevent infection. Heating, Ventilation and Air Conditioning Systems (HVAC) are used as a primary infection disease control measure. However, if not correctly used, they may contribute to the transmission/spreading of airborne diseases as proposed in the past for SARS. The authors believe that airborne transmission is possible and that HVAC systems when not adequately used may contribute to the transmission of the virus, as suggested by descriptions from Japan, Germany, and the Diamond Princess Cruise Ship. Previous SARS outbreaks reported at Amoy Gardens, Emergency Rooms and Hotels, also suggested an airborne transmission. Further studies are warranted to confirm our hypotheses but the assumption of such way of transmission would cause a major shift in measures recommended to prevent infection such as the disseminated use of masks and structural changes to hospital and other facilities with HVAC systems.