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1.
Photochem Photobiol ; 97(3): 532-541, 2021 05.
Article in English | MEDLINE | ID: covidwho-1388390

ABSTRACT

During the current SARS-CoV-2 and tuberculosis global pandemics, public health and infection prevention and control professionals wrestle with cost-effective means to control airborne transmission. One technology recommended by Centers for Disease Control and Prevention and the World Health Organization for lowering indoor concentration of these and other microorganisms and viruses is upper-room ultraviolet 254 nm (UVC254 ) systems. Applying both a material balance as well as some nondimensional parameters developed by Rudnick and First, the impact of several critical parameters and their effect on the fraction of microorganisms surviving UVC254 exposure was evaluated. Vertical airspeed showed a large impact at velocities <0.05 m s-1 but a lesser effect at velocities >0.05 m s-1 . In addition, the efficacy of any upper-room UVC system is influenced greatly by the mean room fluence rate as opposed to a simple volume- or area-based dosing criteria. An alternative UVC254 dosing strategy was developed based on the fluence rate as a function of the UVC254 luminaire output (W) and the square root of the product of the room volume and the ceiling height.


Subject(s)
Air Microbiology , Disinfection/instrumentation , Disinfection/methods , Lighting , Ultraviolet Rays , Air Pollution, Indoor/prevention & control , Animals , COVID-19/prevention & control , Environment, Controlled , Infection Control/methods , SARS-CoV-2/radiation effects , Virus Inactivation/radiation effects
2.
Infect Dis Clin North Am ; 35(3): 697-716, 2021 09.
Article in English | MEDLINE | ID: covidwho-1340668

ABSTRACT

The built environment has been integral to response to the global pandemic of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). In particular, engineering controls to mitigate risk of exposure to SARS-CoV-2 and other newly emergent respiratory pathogens in the future will be important. Anticipating emergence from this pandemic, or at least adaptation given increasing administration of effective vaccines, and the safety of patients, personnel, and others in health care facilities remain the core goals. This article summarizes known risks and highlights prevention strategies for daily care as well as response to emergent infectious diseases and this parapandemic phase.


Subject(s)
COVID-19 , Civil Defense , Health Facilities/trends , Infection Control , Safety Management/organization & administration , COVID-19/epidemiology , COVID-19/prevention & control , Civil Defense/methods , Civil Defense/organization & administration , Environment, Controlled , Hospital Design and Construction/methods , Humans , Infection Control/methods , Infection Control/organization & administration , SARS-CoV-2
3.
PDA J Pharm Sci Technol ; 76(2): 109-119, 2022.
Article in English | MEDLINE | ID: covidwho-1271044

ABSTRACT

In cleanroom facilities, both disposable and reusable textile garments (coveralls, boots, hoods, and frocks) meet the particulate standards from the most rigorous to the most basic levels. However, the reusables clearly offer two other important benefits, lower annual cost and lower environmental impact. The objectives of this article are to now provide quantitative reusable product benefits on a U.S. national environmental and economic basis. This is the first quantitative, novel multi-user economic evaluation of selecting cleanroom reusables over disposables. For personal protection equipment (PPE), these cost and environmental benefits indicate there is also an improved environmental and economic aspect to the increased national demand for reusables related to coronavirus disease 2019 (COVID-19), while necessary cleaning with approved detergents is easily achieved. The current reusable cleanroom market (14.1 million packages) was estimated to be 60% nonsterile and 40% sterilized. The total market is about 50% reusable and 50% disposable. This research documents that there is an annual cost reduction of about 58% when selecting reusables over disposables, giving an economic savings to the U.S. cleanroom sector from reusables of about $1.2 billion in the next decade. This is also saving the total U.S. about 136 million MJ natural resource energy/year (38 million kWh) and about 8.4 million kg CO2eq annually (removal of about 1,650 cars/year). A maximum hypothetical case for reusables at 87.5% of the market (12.5% are mandatory Hazmat disposable) would yield a U.S. national savings of nearly $2.1 billion/decade to the cleanroom sector bottom line, as well as 2.4 billion MJ nre savings in energy or removal of about 29,000 cars/decade. These results indicate there are effective, verifiable, and easily obtained environmental and economic benefits by the basic transition by diverse cleanrooms in deciding to select reusable garments.


Subject(s)
COVID-19 , Disposable Equipment , COVID-19/prevention & control , Cost-Benefit Analysis , Environment, Controlled , Humans , Textiles
4.
J Glob Health ; 11: 10002, 2021 Apr 03.
Article in English | MEDLINE | ID: covidwho-1173057

ABSTRACT

BACKGROUND: This rapid evidence review identifies and integrates evidence from epidemiology, microbiology and fluid dynamics on the transmission of SARS-CoV-2 in indoor environments. METHODS: Searches were conducted in May 2020 in PubMed, medRxiv, arXiv, Scopus, WHO COVID-19 database, Compendex & Inspec. We included studies reporting data on any indoor setting except schools, any indoor activities and any potential means of transmission. Articles were screened by a single reviewer, with rejections assessed by a second reviewer. We used Joanna Briggs Institute and Critical Appraisal Skills Programme tools for evaluating epidemiological studies and developed bespoke tools for the evaluation of study types not covered by these instruments. Data extraction and quality assessment were conducted by a single reviewer. We conducted a meta-analysis of secondary attack rates in household transmission. Otherwise, data were synthesised narratively. RESULTS: We identified 1573 unique articles. After screening and quality assessment, fifty-eight articles were retained for analysis. Experimental evidence from fluid mechanics and microbiological studies demonstrates that aerosolised transmission is theoretically possible; however, we found no conclusive epidemiological evidence of this occurring. The evidence suggests that ventilation systems have the potential to decrease virus transmission near the source through dilution but to increase transmission further away from the source through dispersal. We found no evidence for faecal-oral transmission. Laboratory studies suggest that the virus survives for longer on smooth surfaces and at lower temperatures. Environmental sampling studies have recovered small amounts of viral RNA from a wide range of frequently touched objects and surfaces; however, epidemiological studies are inconclusive on the extent of fomite transmission. We found many examples of transmission in settings characterised by close and prolonged indoor contact. We estimate a pooled secondary attack rate within households of 11% (95% confidence interval (CI) = 9, 13). There were insufficient data to evaluate the transmission risks associated with specific activities. Workplace challenges related to poverty warrant further investigation as potential risk factors for workplace transmission. Fluid mechanics evidence on the physical properties of droplets generated by coughing, speaking and breathing reinforce the importance of maintaining 2 m social distance to reduce droplet transmission. CONCLUSIONS: This review provides a snap-shot of evidence on the transmission of SARS-CoV-2 in indoor environments from the early months of the pandemic. The overall quality of the evidence was low. As the quality and quantity of available evidence grows, it will be possible to reach firmer conclusions on the risk factors for and mechanisms of indoor transmission.


Subject(s)
Air Pollution, Indoor/analysis , COVID-19/transmission , Disease Transmission, Infectious/statistics & numerical data , Environment, Controlled , Environmental Monitoring/statistics & numerical data , Air Pollution, Indoor/prevention & control , COVID-19/prevention & control , Disease Transmission, Infectious/prevention & control , Environmental Microbiology , Humans , SARS-CoV-2
5.
Photochem Photobiol ; 97(3): 532-541, 2021 05.
Article in English | MEDLINE | ID: covidwho-1159007

ABSTRACT

During the current SARS-CoV-2 and tuberculosis global pandemics, public health and infection prevention and control professionals wrestle with cost-effective means to control airborne transmission. One technology recommended by Centers for Disease Control and Prevention and the World Health Organization for lowering indoor concentration of these and other microorganisms and viruses is upper-room ultraviolet 254 nm (UVC254 ) systems. Applying both a material balance as well as some nondimensional parameters developed by Rudnick and First, the impact of several critical parameters and their effect on the fraction of microorganisms surviving UVC254 exposure was evaluated. Vertical airspeed showed a large impact at velocities <0.05 m s-1 but a lesser effect at velocities >0.05 m s-1 . In addition, the efficacy of any upper-room UVC system is influenced greatly by the mean room fluence rate as opposed to a simple volume- or area-based dosing criteria. An alternative UVC254 dosing strategy was developed based on the fluence rate as a function of the UVC254 luminaire output (W) and the square root of the product of the room volume and the ceiling height.


Subject(s)
Air Microbiology , Disinfection/instrumentation , Disinfection/methods , Lighting , Ultraviolet Rays , Air Pollution, Indoor/prevention & control , Animals , COVID-19/prevention & control , Environment, Controlled , Infection Control/methods , SARS-CoV-2/radiation effects , Virus Inactivation/radiation effects
7.
Shock ; 55(4): 472-478, 2021 04 01.
Article in English | MEDLINE | ID: covidwho-1140043

ABSTRACT

INTRODUCTION: Since December 2019, the novel coronavirus SARS-CoV-2 has been spreading worldwide. Since the main route of infection with SARS-CoV-2 is probably via contact with virus-containing droplets of the exhaled air, any method of securing the airway is of extremely high risk for the health care professionals involved. We evaluated the aerosol exposure to the interventional team during a tracheotomy in a semiquantitative fashion. In addition, we present novel protective measures. PATIENTS AND METHODS: To visualize the air movements occurring during a tracheotomy, we used a breathing simulator filled with artificial fog. Normal breathing and coughing were simulated under surgery. The speed of aerosol propagation and particle density in the direct visual field of the surgeon were evaluated. RESULTS: Laminar air flow (LAF) in the OR reduced significantly the aerosol exposure during tracheostomy. Only 4.8 ±â€Š3.4% of the aerosol was in contact with the surgeon. Without LAF, however, the aerosol density in the inspiratory area of the surgeon is 10 times higher (47.9 ±â€Š10.8%, P < 0.01). Coughing through the opened trachea exposed the surgeon within 400 ms with 76.0 ±â€Š8.0% of the aerosol-independent of the function of the LAF. Only when a blocked tube was inserted into the airway, no aerosol leakage could be detected. DISCUSSION: Coughing and expiration during a surgical tracheotomy expose the surgical team considerably to airway aerosols. This is potentially associated with an increased risk for employees being infected by airborne-transmitted pathogens. Laminar airflow in an operating room leads to a significant reduction in the aerosol exposure of the surgeon and is therefore preferable to a bedside tracheotomy in terms of infection prevention. Ideal protection of medical staff is achieved when the procedure is performed under endotracheal intubation and muscle relaxation.


Subject(s)
Aerosols , COVID-19/transmission , Occupational Diseases/etiology , Occupational Exposure , Surgeons , Tracheotomy , Cough/complications , Environment, Controlled , Humans , Operating Rooms , Patient Simulation , Point-of-Care Systems , Respiration , Risk , Virion , Visual Fields
8.
Ann R Coll Surg Engl ; 103(3): 151-154, 2021 Mar.
Article in English | MEDLINE | ID: covidwho-1110067

ABSTRACT

INTRODUCTION: Owing to the COVID-19 pandemic, there has been significant disruption to all surgical specialties. In the UK, units have cancelled elective surgery and a decrease in aerosol generating procedures (AGPs) was favoured. Centres around the world advocate the use of negative pressure environments for AGPs in reducing the spread of infectious airborne particles. We present an overview of operating theatre ventilation systems and the respective evidence with relation to surgical site infection (SSI) and airborne pathogen transmission in light of COVID-19. METHODS: A literature search was conducted using the PubMed, Cochrane Library and MEDLINE databases. Search terms included "COVID-19", "theatre ventilation", "laminar", "turbulent" and "negative pressure". FINDINGS: Evidence for laminar flow ventilation in reducing the rate of SSI in orthopaedic surgery is widely documented. There is little evidence to support its use in general surgery. Following previous viral outbreaks, some centres have introduced negative pressure ventilation in an attempt to decrease exposure of airborne pathogens to staff and surrounding areas. This has again been suggested during the COVID-19 pandemic. A limited number of studies show some positive results for the use of negative pressure ventilation systems and reduction in spread of pathogens; however, cost, accessibility and duration of conversion remain an unexplored issue. Overall, there is insufficient evidence to advocate large scale conversion at this time. Nevertheless, it may be useful for each centre to have its own negative pressure room available for AGPs and high risk patients.


Subject(s)
Air Filters , COVID-19/prevention & control , Environment, Controlled , Operating Rooms , Patient Isolators , Surgical Procedures, Operative/methods , Ventilation/methods , COVID-19/transmission , Humans , Orthopedic Procedures , SARS-CoV-2 , Surgical Wound Infection/prevention & control
9.
Infect Dis Health ; 26(1): 55-62, 2021 02.
Article in English | MEDLINE | ID: covidwho-1065110

ABSTRACT

BACKGROUND: As frontline providers of care, nurses and midwives play a critical role in controlling infections such as COVID-19, influenza, multi-drug resistant organisms and health care associated infections. Improved cleaning can reduce the incidence of infection and is cost effective but relies on healthcare personnel to correctly apply cleaning measures. As nurses and midwives have the most contact with patients and as an important first step in improving compliance, this study sought to explore nurses' and midwives' knowledge on the role of the environment in infection prevention and control and identify challenges in maintaining clean patient environments. METHODS: Cross-sectional online survey of 96 nurses (RN/EN) and midwives (RW) employed in clinical settings (e.g. hospital, aged care, medical centre, clinic) in Australia. RESULTS: Nurses and midwives broadly stated that they understood the importance of cleaning. However, cleaning responsibilities varied and there was confusion regarding the application of different disinfectants when cleaning after patients with a suspected or diagnosed infection post-discharge. Most would not be confident being placed in a room where a previous patient had a diagnosed infection such as multi-drug resistant organism. CONCLUSION: Greater organisational support and improving applied knowledge about infection control procedures is needed. This includes correct use of disinfectants, which disinfectant to use for various situations, and cleaning effectively following discharge of a patient with known infection. The cleanliness of shared medical equipment may also pose current risk due to lack of cleaning.


Subject(s)
Cross Infection/prevention & control , Environment, Controlled , Health Knowledge, Attitudes, Practice , Nurse Midwives/psychology , Nurses/psychology , Adult , Attitude of Health Personnel , Australia , COVID-19/prevention & control , Clinical Competence , Cross-Sectional Studies , Disinfectants , Female , Humans , Male , Middle Aged , Surveys and Questionnaires , Young Adult
11.
J Hosp Infect ; 110: 194-200, 2021 Apr.
Article in English | MEDLINE | ID: covidwho-1062461

ABSTRACT

BACKGROUND: Reducing COVID-19 transmission relies on controlling droplet and aerosol spread. Fluorescein staining reveals microscopic droplets. AIM: To compare the droplet spread in non-laminar and laminar air flow operating theatres. METHODS: A 'cough-generator' was fixed to a theatre trolley at 45°. Fluorescein-stained 'secretions' were projected on to a series of calibrated targets. These were photographed under UV light and 'source detection' software measured droplet splatter size and distance. FINDINGS: The smallest droplet detected was ∼120 µm and the largest ∼24,000 µm. An average of 25,862 spots was detected in the non-laminar theatre, compared with 11,430 in the laminar theatre (56% reduction). The laminar air flow mainly affected the smaller droplets (<1000 µm). The surface area covered with droplets was: 6% at 50 cm, 1% at 2 m, and 0.5% at 3 m in the non-laminar air flow; and 3%, 0.5%, and 0.2% in the laminar air flow, respectively. CONCLUSION: Accurate mapping of droplet spread in clinical environments is possible using fluorescein staining and image analysis. The laminar air flow affected the smaller droplets but had limited effect on larger droplets in our 'aerosol-generating procedure' cough model. Our results indicate that the laminar air flow theatre requires similar post-surgery cleaning to the non-laminar, and staff should consider full personal protective equipment for medium- and high-risk patients.


Subject(s)
Aerosols , Air Microbiology , COVID-19/prevention & control , COVID-19/transmission , Disease Transmission, Infectious/statistics & numerical data , Environment, Controlled , Operating Rooms/statistics & numerical data , Humans , SARS-CoV-2
12.
Paediatr Respir Rev ; 36: 106-108, 2020 Nov.
Article in English | MEDLINE | ID: covidwho-974487

ABSTRACT

The COVID pandemic has passed its first peak for now in many countries while some are still on the rise, with some facing a second wave of cases. Precautions and infection control measures for both pediatric and adult pulmonary function testing (PFT) have been a topic of debate during the pandemic. Many centers had to close their PFT laboratories during the initial periods of the pandemic and are reopening as the numbers of new cases are decreasing. This review aims to summarize different practices of PFT laboratory management in different countries, including patient appointments, personal protective equipment, testing room requirements and telemedicine during and immediately following the COVID pandemic.


Subject(s)
COVID-19/prevention & control , Delivery of Health Care/methods , Environment, Controlled , Personal Protective Equipment , Respiratory Function Tests/methods , Air Filters , Appointments and Schedules , COVID-19/transmission , Child , Delivery of Health Care/organization & administration , Humans , Internationality , Parents , Pediatrics , Physical Distancing , Pulmonary Medicine , Telemedicine , Ventilation , Waiting Rooms
14.
Environ Health Prev Med ; 25(1): 66, 2020 Nov 03.
Article in English | MEDLINE | ID: covidwho-901839

ABSTRACT

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a new zoonotic agent that emerged in December 2019, causes coronavirus disease 2019 (COVID-19). This infection can be spread by asymptomatic, presymptomatic, and symptomatic carriers. SARS-CoV-2 spreads primarily via respiratory droplets during close person-to-person contact in a closed space, especially a building. This article summarizes the environmental factors involved in SARS-CoV-2 transmission, including a strategy to prevent SARS-CoV-2 transmission in a building environment. SARS-CoV-2 can persist on surfaces of fomites for at least 3 days depending on the conditions. If SARS-CoV-2 is aerosolized intentionally, it is stable for at least several hours. SARS-CoV-2 is inactivated rapidly on surfaces with sunlight. Close-contact aerosol transmission through smaller aerosolized particles is likely to be combined with respiratory droplets and contact transmission in a confined, crowded, and poorly ventilated indoor environment, as suggested by some cluster cases. Although evidence of the effect of aerosol transmission is limited and uncertainty remains, adequate preventive measures to control indoor environmental quality are required, based on a precautionary approach, because COVID-19 has caused serious global damages to public health, community, and the social economy. The expert panel for COVID-19 in Japan has focused on the "3 Cs," namely, "closed spaces with poor ventilation," "crowded spaces with many people," and "close contact." In addition, the Ministry of Health, Labour and Welfare of Japan has been recommending adequate ventilation in all closed spaces in accordance with the existing standards of the Law for Maintenance of Sanitation in Buildings as one of the initial political actions to prevent the spread of COVID-19. However, specific standards for indoor environmental quality control have not been recommended and many scientific uncertainties remain regarding the infection dynamics and mode of SARS-CoV-2 transmission in closed indoor spaces. Further research and evaluation are required regarding the effect and role of indoor environmental quality control, especially ventilation.


Subject(s)
Betacoronavirus/physiology , Coronavirus Infections/prevention & control , Coronavirus Infections/transmission , Environment, Controlled , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , Pneumonia, Viral/transmission , Aerosols , Air Pollution, Indoor/prevention & control , COVID-19 , Crowding , Humans , SARS-CoV-2 , Ventilation
15.
BMJ Glob Health ; 5(8)2020 08.
Article in English | MEDLINE | ID: covidwho-736181

ABSTRACT

Respiratory viruses can be transmitted through contact, droplet and airborne routes. Viruses that are not naturally airborne may be aerosolised during medical procedures and transmitted to healthcare workers. Most resource-limited healthcare settings lack complex air handling systems to filter air and create pressure gradients that are necessary for minimising viral transmission. This review explores the association between ventilation and the transmission of respiratory viruses like SAR-CoV-2. When used appropriately, both natural and mechanical ventilation can decrease the concentration of viral aerosols, thereby reducing transmission. Although mechanical ventilation systems are more efficient, installation and maintenance costs limit their use in resource-limited settings, whereas the prevailing climate conditions make natural ventilation less desirable. Cost-effective hybrid systems of natural and mechanical ventilation may overcome these limitations.


Subject(s)
Betacoronavirus , Coronavirus Infections , Environment, Controlled , Pandemics , Pneumonia, Viral , Respiration, Artificial , Africa , Air Microbiology , COVID-19 , Coronavirus Infections/epidemiology , Coronavirus Infections/prevention & control , Coronavirus Infections/transmission , Humans , Pandemics/prevention & control , Patient Isolation , Patients' Rooms , Pneumonia, Viral/epidemiology , Pneumonia, Viral/prevention & control , Pneumonia, Viral/transmission , Respiration, Artificial/adverse effects , Respiration, Artificial/statistics & numerical data , SARS-CoV-2
16.
J Cardiovasc Electrophysiol ; 31(8): 1901-1903, 2020 08.
Article in English | MEDLINE | ID: covidwho-342782

ABSTRACT

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.


Subject(s)
COVID-19/prevention & control , Cardiac Catheterization , Infection Control/standards , Ventilation/instrumentation , Air Pressure , Environment, Controlled , Hospital Design and Construction , Humans , Pandemics , SARS-CoV-2
17.
Med Hypotheses ; 141: 109781, 2020 Aug.
Article in English | MEDLINE | ID: covidwho-116780

ABSTRACT

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.


Subject(s)
Air Microbiology , Betacoronavirus/isolation & purification , Coronavirus Infections/transmission , Environment, Controlled , Pandemics , Pneumonia, Viral/transmission , Ventilation , Aerosols , Air Conditioning/adverse effects , Air Conditioning/instrumentation , Air Conditioning/methods , Air Pollution, Indoor , COVID-19 , Coronavirus Infections/prevention & control , Cross Infection/transmission , Equipment Contamination , Equipment Design , Equipment Failure , Fomites/virology , Heating/adverse effects , Heating/instrumentation , Heating/methods , Humans , Legionnaires' Disease/epidemiology , Legionnaires' Disease/transmission , Models, Biological , Pandemics/prevention & control , Pneumonia, Viral/prevention & control , SARS-CoV-2 , Sanitary Engineering/instrumentation , Severe Acute Respiratory Syndrome/epidemiology , Severe Acute Respiratory Syndrome/transmission , Sewage/virology , Ventilation/instrumentation , Ventilation/methods
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