key: cord-0889264-kqd9vm4l
authors: Shajahan, Amreen; Culp, Charles H.; Williamson, Brandon
title: Effects of indoor environmental parameters related to building heating, ventilation, and air conditioning systems on patients' medical outcomes: A review of scientific research on hospital buildings
date: 2019-01-25
journal: Indoor Air
DOI: 10.1111/ina.12531
sha: 3a4f2e8909adf40a3e542b0021c29e32ec1ac300
doc_id: 889264
cord_uid: kqd9vm4l

The indoor environment of a mechanically ventilated hospital building controls infection rates as well as influences patients’ healing processes and overall medical outcomes. This review covers the scientific research that has assessed patients’ medical outcomes concerning at least one indoor environmental parameter related to building heating, ventilation, and air conditioning (HVAC) systems, such as indoor air temperature, relative humidity, and indoor air ventilation parameters. Research related to the naturally ventilated hospital buildings was outside the scope of this review article. After 1998, a total of 899 papers were identified that fit the inclusion criteria of this study. Of these, 176 papers have been included in this review to understand the relationship between the health outcomes of a patient and the indoor environment of a mechanically ventilated hospital building. The purpose of this literature review was to summarize how indoor environmental parameters related to mechanical ventilation systems of a hospital building are impacting patients. This review suggests that there is a need for future interdisciplinary collaborative research to quantify the optimum range for HVAC parameters considering airborne exposures and patients’ positive medical outcomes.

rates, 20, 23, 38 and can improve the indoor air quality (IAQ) and minimize HAI. 39 An improved indoor environment of a hospital building can reduce costs associated with airborne illnesses by 9%-20%. 40 To establish the relationship between health outcomes and the physical environment, Rubin et al 30 

where parameters including room size, room privacy, interior design of a room, patient control of his/her environment, music, lighting, exposure to sunlight, window view of nature, ventilation system contaminants, humidity, and temperature have been reviewed. Among these studies on the effect of healthcare environment on patient outcomes, seven were on humidity; four on air filtration system; four on ventilation system; two on temperature; one on (increase outside air changes, improve filter efficiency, maintain constant temperature and humidity, increase positive pressure of operating room air). They 30 concluded that there is convincing evidence linking patients' clinical outcomes and built environment parameters. Zimring et al 32 identified a connection between the hospital indoor environment and patient and staff outcomes with respect to four sectors: staff stress and fatigue reduction and increased effectiveness in delivering care; patient safety improvement; stress reduction and improvement in patient outcomes; and overall healthcare quality improvement. Dijkstra et al 23 summarized literature on environmental stimuli (eg, furniture, art, color, nature, plants, gardens, carpeting, room size, spatial layout, private rooms, noise, music, odor, television/video, light, windows, and view from a window) and their impact on patients' psychological outcomes rather than on direct physiological outcomes. Huisman et al 25 reviewed hospital interior layouts and their relationship with medical staff error, patient falls, infection rates, indoor quality, comfort, building materials, visual comfort, acoustics, view, and privacy. They covered the indoor environment (eg, ambient temperature, humidity, ventilation strategies, and air quality) under the subtopic of safety and security, not patients' medical outcomes. 25 Previous studies related to the hospital building's indoor environment discretely focused on patients' thermal comfort, 35, [41] [42] [43] [44] [45] acoustic comfort, 46 visual comfort, and IAQ. [47] [48] [49] [50] The impacts of single or multiple indoor environmental parameters related to the mechanical ventilation system on overall patient outcomes have not been summarized yet. Hence, this review covers the findings from the published scientific literature on the associations of temperature, relative humidity, ventilation rate, air filter, differential pressure, and ventilation strategy, with patient outcomes. This literature review considered articles published after 1998 and was restricted to codes, guidelines, and standards published by professional societies, licensing agencies, and regulatory organizations. Studies related to natural ventilation for infection control are outside of the scope of this review. Additionally, parameters related to building design, architecture, interior design, noise, aroma, and lighting are being excluded from the scope of this literature review, since this review exclusively focuses on parameters related to the HVAC systems. This review will help researchers, policymakers, healthcare, and building design professionals to understand the importance of indoor environmental parameters and provide information for enhancing standards related to the HVAC systems in attaining positive medical outcomes for patients. The review also identified avenues for future interdisciplinary collaborative research to quantify the optimum range for indoor environmental parameters considering patients' positive medical outcomes.

A multidisciplinary reviewing process was adopted to find out both quantitative and qualitative academic research evidence on indoor environmental parameters and their impact on patients' medical outcomes. PubMed [Medline] , JSTOR, ScienceDirect, Scopus bibliographic databases, Google Scholar, and Texas A&M University Library databases were searched for 58 keywords. Combination keywords, such as "ambient temperature AND patient outcomes," "mechanical ventilation system AND patient outcomes," "indoor air quality AND patient outcomes," "airflow AND patient," "mechanical ventilation AND infection," "physical environment AND patient outcomes," and others were used as well to confine the search area. Scientific publications in the fields of both hospital buildings and parameters related to the HVAC system of a mechanically ventilated building were reviewed. Also, the citations in each study found during the main search were reviewed for potential relevance. This paper includes relevant articles that were published after the review done by Rubin et al. 30 Through a systematic review process, a total of 1871 abstracts were screened, with a total of 899 papers being identified as relevant to the scope of this study. These articles went through a fulltext review process and were excluded if the patient outcomes were not biological and physiological, or if the built environment parameters are not related to the building HVAC system, variables such as

• The indoor environment of a mechanically ventilated hospital building controls infectious disease transmission and influences patients' outcomes.

• A summary of the recommended optimum ranges of temperature, relative humidity, ventilation rates, air filtration, differential pressure control, and ventilation strategies will be beneficial for the patients' wellbeing.

• These findings from the published scientific literature will be helpful for researchers, policy-makers, healthcare and building design professionals in enhancing standards related to the HVAC systems considering patients' outcomes.

• Future interdisciplinary collaborative research has been identified and can lead to specific optimum ranges for indoor environmental parameters in different spaces for hospital buildings.

noise, aroma, light, and other building layouts and interior design.

Additionally, research on naturally ventilated hospital buildings was excluded as well since this review article solely focuses on the parameters related to the mechanical ventilation system of a hospital building. As a result, 176 articles have been included in this review paper. However, articles that partially fulfilled the objective of this review were included. For example, papers concentrating on both patient and staff outcomes were evaluated, though only patients' outcomes related study were included in this review paper. Among 176 papers in this review, 133 investigated patients' outcomes as a function of at least one indoor environmental parameter related to building HVAC systems.

The article selection process is shown in Figure 1 . All the references of these articles were verified and crosschecked.

Patient outcomes are dependent on the indoor environment of a hospital building. 19, 33, [51] [52] [53] Previous research on evidence-based design for healthcare facilities has established that hospital-acquired infection rates are directly related to IAQ. 17, 25, 45, [54] [55] [56] [57] Patients' psychological health is affected by poor indoor environment. 58, 59 Studies have demonstrated an association between environmental variables and "Sick building syndrome" (SBS). [60] [61] [62] Patients and elderly in hospitals and nursing homes are sensitive to these specific building-related illness caused by SBS; they are hypersensitivity pneumonitis; building-related asthma; and legionellosis. 61 Environmental parameters can be modified to improve the physical environment and promote patients' positive health outcomes. 15, 16, 32, 33 Kameel and Khalil 63 and grouped these environmental parameters to "ergonomics," "fabric and ambient," "art and esthetics," and "services." To propose a framework based on a cause-effect relationship, they categorized patient health outcomes under three sections: psychological, physical, and physiological. 22 They concluded that the indoor environment of a healthcare facility has a considerable impact on patients' health outcomes. 22 Rashid and Zimring 65 This review focuses on summarizing published literature that investigates the impact of each or multiple indoor environmental parameters on patient outcomes. The following section will categorize studies related to patient medical outcomes under indoor air temperature, relative humidity, indoor air ventilation rate, air filtration system, differential pressure control, and mechanical ventilation strategies. 

Potential airborne pathogens such as bacteria, viruses, and fungi can pose severe health effects. 67 The susceptibility of patients to nosocomial pathogens depends on the pathogen's survivability on various surfaces. 68, 69 Temperature is one of the major factors that influence the transmission and survivability of these microorganisms. [70] [71] [72] Low ambient temperature increases influenza virus transmission since the survivability of infectious agents rises. 73, 74 The optimum temperature to control the survival of airborne influenza viruses is as high as 30°C (86°F) at 50% relative humidity, 75 which will create an uncomfortable indoor environment as per ASHRAE a Standard 55. 76 Through an experimental study, Lowen et al 73, 77 concluded that at 20°C (68°F) influenza virus transmission is dependent on humidity, but at the higher temperature (30°C; 86°F), the transmission was eliminated regardless of relative humidity. Low temperature is associated with longer persistence of most viruses, such as the astrovirus, 78 adenovirus, poliovirus, herpes simplex virus, and hepatitis A virus. 68, 69 Most bacteria, fungi, and viruses are more stable and persist longer at low temperatures, such as 4°C (39.2°F) or 6°C (42.8°F). 69 Tang 75 focusing on the disease-oriented evidence reviewed the survival of airborne infectious bacteria in relation to indoor air temperature. He Cryptococcus; and Histoplasma species. 80 Unlike the laboratorybased testing for viruses and bacteria, air sampling testing to identify the presence or absence of fungi and their spores in natural settings revealed higher spore counts at a higher temperature, 75 

Indoor air temperature is important for patients' thermal comfort perception. 83 Thermal comfort has an impact on patients' healing processes, 35, 84 satisfaction with surgical care, 85 well-being, and safety. 35, [86] [87] [88] Due to medication and drug use, a patient's thermoregulatory system affects the overall perception of thermal comfort. 89 Uncomfortable environments have negative effects on patients, such as sleeplessness and restlessness, 86 and can cause shivering, inattentiveness, and muscular and joint tension. 63, 85, [90] [91] [92] [93] [94] Maintaining thermal comfort in an operating room (OR) is a challenge since the situation varies with the surgery types, various patient requirements, various activity levels of hospital staff, different interior settings of lights and equipment, and the total number of occupied people at a certain time. 43, 95 It is recommended to modulate the OR temperature according to the need of each surgery type for optimum comfort level. 19 Studies have identified the correlation between low ambient room temperature and hypothermia among patients during the perianesthesia or perioperative period. 101, [106] [107] [108] Since high ambient temperature (>23°C or 73.4°F) is required to avoid perioperative hypothermia, it may be found uncomfortable for the OR personnel. 109, 110 Surgical site infection is one of the leading effects of even mild hypothermia, where a 1.9°C (3.42°F) reduction in core body temperature increases the chance of SSI three times in a patient after 236 Association of Perioperative Registered Nurses, 237 Morris, 104 Morris and Wilkey, 105 112 and cause a prolonged post-anesthetic recovery. 113 Perioperative hypothermia poses a relative risk of severe complications, such as cardiac events, [115] [116] [117] [118] blood loss, 114 impaired wound healing, [115] [116] [117] wound infections, 119 an increased rate of morbidity and mortality, 114, 115, 120, 121 length of hospital stay, and the cost of treatment. [115] [116] [117] Higher ambient temperature is recommended during anesthetic induction and surgical skin preparation; conversely, a lower ambient temperature is recommended before surgical incision. 19 However, this method has limited effectiveness among adult patients because of the time interval for warming the room is relatively brief and requires wide swings in temperature to have a significant clinical effect. 122 A study on critically ill trauma patients confirmed that there is no correlation between the decrease of ambient OR temperature and patient core body temperature with effective use of active warming strategies on patients. 123, 124 Controlling indoor air temperature is crucial for other severely ill patients (eg, burn victims)

where the application of active warming strategy is difficult. 19, 86 Thermal stability is important for preterm infants to reduce harmful side effects, such as delayed adaptation to extrauterine life, hypoglycemia, respiratory distress, hypoxia, metabolic acidosis, coagulation defects, acute renal failure, necrotizing enterocolitis, and failure to gain weight or weight loss and morbidity. 125-127

In hospital buildings, evidence has confirmed that RH affects infection control because it is related to the growth and transfer of airborne bacteria, 128 some strains of viruses, and fungi. 35, 83, 129 A strong correlation has been found between the transmission of viruses and absolute humidity, 74 75 Kramer et al, 69 Tang et al, 134 Cox 144 Airborne gram-positive bacteria 

Higher RH Kramer et al, 69 Tang et al 134 Relative humidity has an impact on the viability of both airborne and droplet transmission of viruses. 75, 143 However, this relationship is quite complex. Both lipid-enveloped and non-lipid-enveloped viruses are less stable at relative humidities between 40% and 70%, 143 while an ideal range for the airborne influenza survival is 23%-81%. 73 A study 131 

In a hospital building, RH levels are related to patients' indoor thermal comfort and hygiene of spaces. 35 

Pathogens and other respiratory viruses, such as influenza, 134 

Ventilation rates are measured as ACH, that is, how many times the air in a defined space is replaced per hour. Several comprehensive literature reviews on ACH and infectious disease transmission concluded that there is insufficient evidence to specify the minimum and maximum ventilation requirements in hospitals based on infection control risk to patients. 152 . 179 A study in a simulated two-bed hospital isolation room with mixing air distribution system showed that the elevated ventilation rates might increase the risk of airborne cross-infection. 173 The exposure level depended on the positioning and distance from the source, and posture of the infected patients. 173 The recommended 12 ACH in the present standards and guidelines resulted in draft discomfort within the occupied zone due to higher air velocities. 173 Conversely, across-sectional observational study by Menzies et al 154 184 A study on 4-bed patient rooms showed a minor reduction in infectious disease transmission through hand colonization when ventilation rates change from four ACH to six ACH. 185 The results of a CFD simulation in the general wards of Hong Kong hospitals showed that a flow rate of nine ACH effectively minimized infection risk of three respiratory viruses. 186 Table 3 

The ventilation strategy and air distribution pattern in a hospital building are correlated with the airborne transmission of infectious agents. 152, 158, [188] [189] [190] This section will evaluate the role of various ventilation strategies in removing airborne pathogens from different spaces in hospitals.

CFD analysis found that in patient rooms, displacement ventilation made larger bioaerosols (>10 μm) suspend in the air for longer periods, whereas smaller particles were able to escape the space. 191 Another experimental study concluded that in multiple bed patient rooms, the spacing between beds should be farther apart with the displacement ventilation strategy compared with mixing the air. 192 Qian et al 192 also concluded that the exhaled nuclei droplet from infected patients penetrates long distances during displacement ventilation, and takes longer to dissipate than mixing ventilation strategies.

A comparative experimental study for hospital wards showed that the displacement ventilation system would have higher contaminant concentration than a mixing ventilation system if the auxiliary exhaust is located to the lower part of the wall. 193 However, when the exhaust was relocated at the upper part of the wall, the displacement ventilation at 4 ACH showed lower contaminant concentration than traditional mixing ventilation at six ACH. 193 Another study with a similar conclusion added that, for better performance, supply air diffusers should be unobstructed and located at a lower level and toilet transfer grilles at a high level. 194 Conversely, a study on two floor-supply-type ventilation flow patterns showed that unidirectional-upward system was more efficient in removing the smallest droplet nuclei (<1.5 μm), but the single-side-floor system was effective at removing large droplets and droplet nuclei. 188 Another study on supply air inlet locations showed that the underfloor air distribution system performs better in reducing bioaerosol concentration than the ceiling type and side wall supply systems. 196 Experimental test chamber results and Eulerian-Lagrangian computations revealed that the mixing ventilation system has a positive influence on bioaerosol dispersion. 176 ward with a ceiling-mixing type ventilation system showed that the dispersions of airborne contaminants were significantly affected by the location of the exhaust air vents. 197 They also concluded that the decay rate of contaminant concentration is exponential with a complete mixing ventilation system. 197 Using an engineering computational technique for the isolation room, researchers have found that the parallel-directional airflow pattern and staggered air-supply and exhaust vents positioning can efficiently control infectious disease contamination. 198 This study also concluded that the ceiling to floor level ventilation airflow resulted in poor infection control. 198 An analytical CFD study in hospital ward showed that when the air was supplied and extracted through the ceiling, it was more effective in removing airborne pathogens compared with other strategies. 189 After reviewing 20 ORs, Balaras et al 128 summarized that for quicker dissipation of contaminated air, laminar downward airflow was found to be effective with air changes ranging from 3.2 to 58 ACH. Another simulated study showed that positioning the ventilation grills at the ceiling removes the aerosol more quickly than the wall ventilation system. 189 For downward air movement, Khalil 199 recommended the supply air outlets need to be located at the ceiling and the exhaust inlets on the opposite walls. The optimum location of supply outlets is crucial to reduce the residence time of pollutants efficiently. 95 In ORs, laminar airflow can limit surgical-site infections by lessening the bacterial air contamination. 65 

A high-efficiency particulate air (HEPA) filtration system can reduce the load of bacteria, which is the most common cause of hospital-associated infections 203 and other infectious particles. 204 

Differential pressure is important to control the contamination of airborne infectious agents through airflows between the protective and less protective spaces of a hospital building. 157, [224] [225] [226] In a hospital building, pressurization or depressurization relative to its surroundings needs to be maintained in the microbiology laboratories, the anteroom to AIIRs, AIIRs, autopsy suites, bronchoscopy rooms, emergency department and radiology waiting rooms, and

ORs or surgical rooms. 226 AIIRs need to be maintained at negative differential air pressure ("negative" means that the air pressure of the area is lower than the adjacent spaces) to avoid contamination from patients with highly infectious diseases (ASHRAE 170-2008 as cited in Aliabadi et al 161 ) . Sterilizing spaces and service zones, such as laundry and bathrooms, should be negatively pressurized. 161 In contrast, surgery rooms should continuously maintain positive differential air pressure to avoid particle infiltration. 161 

In a hospital building, the built environment can have a beneficial impact on patients' healing processes. 12, 22, 23, 25, 29, 30, 32, 34, 35, 38, 43 This review covered the published research that has assessed patients' medical outcomes with respect to at least one indoor environmental parameter related to the mechanical ventilation system of a building including temperature, relative humidity, and overall IAQ. Scientific publications in the fields of both healthcare and building HVAC systems published after the review paper of Rubin et al 30 164 and it depends on other parameters, such as air distribution pattern; position and distance of the susceptible person from both source and air diffusers; and position and posture of infected source. 134, 173, 177, 179, 183 Results from both experimental and computational studies confirmed that for patient rooms, the mixing ventilation strategies showed better contamination control and lowered the infectious disease transmission risks. 176, 181, 189, [192] [193] [194] [195] For multiple bed patient rooms, displacement ventilation strategies may not be suitable unless beds are placed apart; the exhaust is located at the upper part of the wall;

and unobstructed supply air diffusers are located at a lower level of the wall. Additionally, the posture and distance between two persons (source and target) have impacts on the contaminant concentration profile. These results are highly dependent on a subject's position and distance from the source of the contaminant 181, 194 ; location of the vents 189, 193, 194, [196] [197] [198] [199] ; and ventilation rates. 128, 176 Along with appropriate ventilation strategies, the HEPA filtration system can effectively reduce the contamination load. [204] [205] [206] [207] [208] [209] [210] [211] [217] [218] [219] However, maintaining the differential air pressure with respect to the adjacent spaces is very critical since the HEPA filters within ducts may have limited control over airborne nosocomial infections due to contaminated air from adjacent spaces. 220 In order to control airborne contamination through pressurization-depressurization in critical areas of a hospital building, important considerations are leakage in room pressure control 232 (e) air distribution pattern; and (f) location of the air filtration system.

Based on this literature review, temperature, humidity, and the indoor air ventilation system in hospital buildings affect various infectious organisms, which then have an effect on patient outcomes. Published results contain contradictory findings, which made the comparative assessment difficult due to inconsistency in experimental design, choice of variables, location and settings, demographics, diseases, patients, and the types of outcome measurements. Hence, it is impossible to make evidence-based decisions regarding the optimum ranges to improve patient-oriented outcomes such as symptoms, morbidity, quality of life, or mortality. These contradictory results of the current research suggest that all indoor environmental parameters related to the HVAC system need to be measured or included in the comparative analysis of each study. Additionally, a common set of variables need to be defined for comparative analysis.

A few epidemiological studies have been undertaken specifically to investigate the suitable ranges of multiple indoor environmental parameters (eg, temperature, RH, ACH); there is little patientoriented evidence to formulate guidelines for hospitals. While extensive simulation-based research has been performed, very little patient-oriented evidence has been produced. For validation, simulations and experiments need to correlate by physical measurements.

Additional multidisciplinary studies including researchers, patients, building owners, facility managers, and maintenance staffs studies are needed, which would address evidence-based decisions regarding the optimum ranges to improve patient-oriented outcomes.

Studies that look at nosocomial infection rates, the spread of infection within hospitals, and associated costs are potential avenues of research. A multidisciplinary study combining available molecular biology testing, advanced computer modeling, experimental testing, and on-site experimental designs could provide evidence to identify optimum ranges for temperature, humidity, and ACH along with appropriate ventilation design strategies. It is also necessary to address these variables as a function of spaces within a hospital since each zone has unique occupants and different functionality. Additionally, the structural variation of infectious agents (ie, viruses, bacteria, and fungi) may need to be considered separately when investigating airborne survival since each will have differing conditions under which they may be optimally suppressed. Finally, the relationship between IEQ variables, thermal comfort perception of patients, and airborne contamination need to be investigated. The health effects of ventilation in locations with highly polluted outdoor air and other diverse outdoor conditions present an important area of future research.

We specially acknowledge the Energy Systems Laboratory, Texas A&M University for support. 

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Comparison of operating room ventilation systems in the protection of the surgical site/discussion

Methodology for minimizing risk from airborne organisms in hospital isolation rooms

An experimental and numerical study on deposition of bioaerosols in a scaled chamber

Role of air changes per hour (ACH) in possible transmission of airborne infections

Particulate concentrations within a reducedscale room operated at various air exchange rates

Adequacy of air change rate as the sole indicator of an air distribution system's effectiveness to mitigate airborne infectious disease transmission caused by a cough release in the room with overhead mixing ventilation: a case study

Ventilation rates and airflow pathways in patient rooms: A case study of bioaerosol containment and removal

Distribution of exhaled contaminants and personal exposure in a room using three different air distribution strategies

Exposure to coughed airborne pathogens in a double bed hospital patient room with overhead mixing ventilation: Impact of posture of coughing patient and location of doctor

Bioaerosols in health-care environments

Effect of operation room geometry and ventilation system parameter variations on the protection of the surgical site. IAQ Conference

Modeling environmental contamination in hospital single-and four-bed rooms

Ventilation of general hospital wards for mitigating infection risks of three kinds of viruses including Middle East respiratory syndrome coronavirus

New ventilation guidelines for health-care facilities

Transport characteristics of expiratory droplets and droplet nuclei in indoor environments with different ventilation airflow patterns

The ventilation of multiple-bed hospital wards: review and analysis

Contaminant flow in the microenvironment between people under different ventilation conditions

Comparison of indoor aerosol particle concentration and deposition in different ventilated rooms by numerical method

Dispersion of exhaled droplet nuclei in a two-bed hospital ward with three different ventilation systems

Experimental study on displacement and mixing ventilation systems for a patient ward

Healthcare ventilation research collaborative: displacement ventilation research: phase II summary report. Healthcare Without Harm

Impact of moving objects on contaminant concentration distributions in an inpatient ward with displacement ventilation

Experimental measurements and numerical simulations of particle transport and distribution in ventilated rooms

Dispersion of expiratory droplets in a general hospital ward with ceiling mixing type mechanical ventilation system

Virus diffusion in isolation rooms

Air-conditioning systems' design in hospitals for comfort, air quality, and energy utilization

Design of Hospital Operating Room Ventilation using Computational Fluid Dynamics. Doctoral dissertation, KTH Royal Institute of Technology

Impact of different-sized laminar air flow versus no laminar air flow on bacterial counts in the operating room during orthopedic surgery

Laminar air flow provides high air quality in the operating field even during real operating conditions, but personal protection seems to be necessary in operations with tissue combustion

Nosocomial bloodstream infections in United States hospitals: a three-year analysis

HVAC filtration for controlling infectious airborne disease transmission in indoor environments: predicting risk reductions and operational costs

Prospective survey of indoor fungal contamination in hospital during a period of building construction

Bacterial communities in commercial aircraft high-efficiency particulate air (HEPA) filters assessed by PhyloChip analysis

Relationship between environmental fungal contamination and the incidence of invasive aspergillosis in haematology patients

Environmental controls in operating theatres

The addition of a mobile ultra-clean exponential laminar airflow screen to conventional operating room ventilation reduces bacterial contamination to operating box levels

Efficacy of high-efficiency particulate air filtration in preventing aspergillosis in immunocompromised patients with hematologic malignancies

Invasive pulmonary aspergillosis in neutropenic patients during hospital construction: before and after chemoprophylaxis and institution of HEPA filters

Fungal infections after haematology unit renovation: evidence of clinical, environmental and economical impact

The utility of intensified environmental surveillance for pathogenic moulds in a stem cell transplantation ward during construction work to monitor the efficacy of HEPA filtration

The influence of high-efficiency particulate air filtration on mortality and fungal infection among highly immunosuppressed patients: a systematic review

Novel preventative strategies against invasive aspergillosis

Fungal surveillance of an open haematology ward

Use of HEPA filters to reduce airborne concentrations of Pseudomonas aeruginosa

Further evaluation of alternative air-filtration systems for reducing the transmission of porcine reproductive and respiratory syndrome virus by aerosol

Characterization of infectious aerosols in health care facilities: an aid to effective engineering controls and preventive strategies

The use of engineering controls to disinfect Mycobacterium tuberculosis and airborne pathogens in hospital buildings

Efficacy of photocatalytic HEPA filter on microorganism removal

Collection of fungal spores on air filters and spore reentrainment from filters into air

The impact of portable high-efficiency particulate air filters on the incidence of invasive aspergillosis in a large acute tertiary-care hospital

guideline for isolation precautions: preventing transmission of infectious agents in health care settings

Guidelines for preventing the transmission of Mycobacterium tuberculosis in healthcare settings

Guidelines for preventing the transmission of Mycobacterium tuberculosis in health-care settings

Indoor environmental quality and infection control in surgery rooms: Code requirements vs. performance motivation. A critical review

Health-care IAQ: guidance for infection control. Heating/piping/air

Tuberculosis infection control: a practical manual for preventing TB

Energy-efficient ventilation control strategies for surgery rooms

An experimental study on ventilation efficiency of isolation room

Multizone modeling of strategies to reduce the spread of airborne infectious agents in healthcare facilities

Containment testing of isolation rooms

The effect of pressure differential and care provider movement on airborne infectious isolation room containment effectiveness

Perioperative shivering physiology and pharmacology

ASPAN's evidence-based clinical practice guideline for the promotion of perioperative normothermia

Association of periOperative Registered Nurses. Recommended practices for the prevention of unplanned perioperative hypothermia

Effects of different operating room temperatures on the body temperature undergoing live liver donor hepatectomy

Heat loss prevention for preterm infants in the delivery room

Thermoregulation and heat loss prevention after birth and during neonatal intensive-care unit stabilization of extremely low-birthweight infants

Survival of a Pseudomonas fluorescens and Enterococcus faecalis aerosol on inert surfaces