FAQs on Practicing IH in a Pandemic
and the Industrial Hygienist
Map of coronavirus spread as of April 6, 2020. Credit: Johns Hopkins University & Medicine Coronavirus Resource Center.
Editor's note: Given the rapidly developing COVID-19 pandemic, The Synergist is providing early digital access to the cover article for our May 2020 issue. The rest of the issue will be published online in early May.

The original version of this article incorrectly specified the unit of measurement in its discussion of the potential of ultraviolet light to sterilize influenza virus. The correct unit of measurement is microwatts per centimeter squared (µw/cm2). The article was updated on April 17, 2020.
Much of this article was completed on March 31, 2020, when cases of SARS-CoV-2 (the virus that causes COVID-19) were increasing exponentially throughout the world and in some areas of the United States. However, the lack of adequate universal testing was skewing the case numbers such that the number of actual cases was much greater than reported. As we assembled this article, we could not predict whether or to what extent COVID-19 might still be with us, yet most experts anticipated that the number and severity of cases, as well as shortages of medical and protective equipment, would get worse before they improve. We hope that as you are reading this article the worst will have passed and that all of us, especially those practicing in the healthcare arena, are back to their “normal” processes, workdays, and hours. 
This article discusses, in question-and-answer format, aspects of COVID-19 believed to be relevant to industrial hygienists and the overall health and safety community. The questions and answers were selected based on the authors’ experiences on the front lines, their work with healthcare professionals caring for confirmed or suspected COVID-19 patients, and their knowledge and experience in the topic areas. We acknowledge that the information provided may not be as timely as desired and that some of the answers may need revision or augmentation over time. We also recognize that not all IH practices include a healthcare component or some form of coronavirus response. However, we believe that many safety and health professionals need to respond to pandemics in some manner, and we hope that the information will be useful to most readers. We welcome your thoughts and comments regarding the topics discussed below and hope you will share other questions and ideas for a follow-up article.
WHAT IS THE COVID-19 DISEASE, HOW IS IT TRANSMITTED, AND WHO ARE SUSCEPTIBLE POPULATIONS? STEPHEN DERMAN: COVID-19, an acronym for Coronavirus Disease 2019, is a viral disease caused by the newly identified and “novel” COVID-19 virus. The coronavirus family was also responsible for both Severe Acute Respiratory Syndrome (SARS), which caused 8,000 cases and 800 deaths, and Middle East Respiratory Syndrome (MERS), which caused 2,500 cases and 800 deaths.  COVID-19 viruses are single-stranded RNA lipid-enveloped viruses, with symptoms that could be described as mild to flu-like; however, approximately 80 percent of individuals who tested positive for COVID-19 reported only slight symptoms or none at all. Because individuals infected with COVID-19 may not be symptomatic, isolating them in the population is difficult without adequate testing. More severe symptoms necessitate prompt medical assistance, potentially including intensive care and ventilation support.  The first COVID-19 cases originated in China during December 2019. Delays in reporting and reacting to the outbreak in China, and slow reaction in other countries, led to worldwide dissemination of the virus through infected individuals traveling around the globe. Numerous factors beyond the scope of this article contributed to the severity associated with the spread of COVID-19 in various countries. As of March 29, there were over 716,000 worldwide confirmed cases affecting 177 countries, with almost 34,000 deaths, and 149,000 reported recoveries in the more severe cases. The United States had the highest number of cases with approximately 137,000; Italy and China were next with 98,000 and 82,000, respectively, although cases in the U.S. were increasing rapidly while cases in China remained relatively stable as this article was written. COVID-19 replicates extensively in the respiratory system, entering through the mucous membranes of the mouth, nose, and eyes. The most common transmission occurs when one is in the proximity (typically within approximately six feet) of an infected person who coughs, sneezes, or breathes. However, as confirmed by a recent paper published in the journal MedRXiv, contaminated surfaces and airborne particles may also be sources of transmission. People instinctively touch their mouths and nose when they cough, sneeze, eat, or yawn, and then touch inanimate objects such as phones, keyboards, chairs, desks, door handles, and faucets, as well as other people. This contact provides a means of cross-contamination when others touch these surfaces and then the mucous membranes on their faces. Handwashing is a primary preventive method because hands act as an avenue of transmission in both directions.  According to the Centers for Disease Control and Prevention, individuals with increased susceptibility to more severe COVID-19 illness include those over sixty and those with underlying health issues, serious cardiovascular conditions, moderate to severe lung disease or asthma, immune system deficiencies, obesity, and underlying medical conditions (such as diabetes and renal and liver disease). Stress or stressors may aggravate one’s health; thus, everyone should make every effort to exercise, avoid stress, and take time to relax. However, younger, apparently healthy people may still have severe symptoms requiring hospitalization. Because only a limited amount of data is available describing ill and healthy individuals in corresponding age groups, predicting particular health vulnerabilities in different age groups is difficult.  WHAT IS AN EXAMPLE OF A UNIQUE VIRUS TRANSMISSION AND EXPOSURE ROUTE? STEVE WELTY: One unique example would be toilet aerosolization. Although diarrhea does not occur in the majority of COVID-19 cases, the coronavirus has been isolated in stool samples, and numerous studies have demonstrated the ability of biological particles to be aerosolized through toilet flushing. For a virus, a flushing toilet event is like being whipped up in a frothing undercurrent and launched airborne in a water droplet. That droplet quickly evaporates, becoming a “droplet nuclei,” which can stay airborne for hours and also be sucked upwards into the bathroom fan’s exhaust. Toilet-aerosolized droplet nuclei lifted into the breathing zones of unsuspecting individuals can be breathed into their lungs. Studies in the Journal of Applied Microbiology (JAM) and the American Journal of Infection Control (AJIC) indicate that for seven to twelve flushes later, airborne microbes are still being aerosolized. For the JAM study, airborne concentrations of 2,420 plaque-forming units per meter cubed (pfu/m3) of the MS2 phage above a toilet were measured via flushed simulated diarrhea. COVID-19 is known to be present in stools, and diarrhea is a symptom of viral infections, including in some COVID-19 cases. Research performed in Wuhan and published in bioRxiv showed that air sampling in two hospitals found COVID-19 RNA concentrations (19 copies/m3) in patient toilet rooms. In Toronto during the 2003 SARS epidemic, scientists identified airborne SARS viruses in the rooms of symptomatic SARS patients. In a 2019 study published in AJIC, scientists aerosolized bacteria via toilet flushing, demonstrating that bacteria could migrate out of a hospital bathroom and into the patient’s room, potentially infecting individuals in either room.  The toilet as a significant airborne exposure route might best be understood by a 2014 study in Clinical Infectious Diseases regarding a SARS-infected individual who toilet-aerosolized SARS, with the window-exhausted fan disseminating the virus outdoors as far as 600 feet. In what is now understood as the largest known airborne disease event ever recorded, as many as 434 people downwind were believed to have been infected. HOW ARE WE CONTROLLING COVID-19 DISEASE? STEPHEN DERMAN: Primary among control methods is isolation and source control. People who could spread contamination are the source. Since infected individuals who can transmit the virus may not be symptomatic, each of us should frequently practice the recommendations provided in CDC and World Health Organization guidelines including physical distancing, hand hygiene, decontamination of high-touch surfaces, hand and respiratory protection, and isolation where warranted. Everyone, especially those who are more susceptible, should be cautious during the pandemic. We should assume that everyone is a carrier, avoid gatherings, and isolate from others where appropriate (for example, when we or they are known to be infected or were in close contact with an infected individual). In addition, CDC recommends that more susceptible individuals should practice more rigorous social isolation. Treatment options are focused on individuals with signs and symptoms of COVID-19 disease. There are currently several experimental medications undergoing clinical trials at select facilities. Some promising medications involving compassionate use are underway and may have limited availability. WHAT INFECTION PREVENTION CONTROLS ARE HOSPITALS UTILIZING FOR COVID-19 PATIENTS, AND HOW CAN INDUSTRIAL HYGIENISTS HELP? CYNTHIA ELLWOOD: In the healthcare environment, the infection preventionist must protect healthcare workers from contagions that can be acquired through contact, droplet, and airborne transmission. Generally, when patients have been diagnosed with contagious diseases, they are put on isolation precautions that will protect healthcare workers based on the mode of disease transmission.  Contact precautions protect the worker from diseases that are transmitted through direct patient contact and contact with fomites (potentially contaminated items and surfaces). Contact precautions consist of healthcare workers wearing disposable gloves and gowns while in the patient room. Patients can generate infectious respiratory “droplets” through coughing, sneezing, and talking, or while undergoing procedures such as bronchoscopy or suctioning. Droplets pose a potential risk to healthcare providers in close proximity to the patient, and droplet-based PPE precautions for the healthcare provider typically include a minimum of ASTM Level 1 masks (such as surgical masks), eye protection, and disposable isolation gowns and gloves, and patient rooms with neutral-pressure conditions. In contrast, airborne precautions for the healthcare worker include placing patients within negative-pressure isolation rooms and utilizing N95-or-higher efficiency respirators, eye protection, disposable isolation gowns, and gloves. In the healthcare environment, controls necessarily rely on respiratory protection and other PPE for healthcare workers in close proximity to infected patients. Ideally, all COVID-19 patients would be placed into negative-pressure isolation rooms, and all healthcare providers would use PPE consistent with airborne isolation precautions. However, the shortage of PPE, as well as the number of isolation rooms, has forced healthcare to alter infection prevention strategies. (For more information, refer to CDC’s guidance on optimizing the supply of facemasks.)
Industrial hygienists would categorize both droplet and airborne precautions as methods to control aerosol transmission. IHs recognize that the hierarchy of controls prioritizes engineering controls, followed by administrative controls, and finally PPE, including the use of respiratory protection. Numerous guidance documents and publications regarding engineering controls are available to assist the IH in identifying, implementing, and confirming appropriate engineering controls in a pandemic. For more information, refer to resources from the Minnesota Department of Health (PDF) and an ASHRAE paper on bioareosols (PDF) and web page on negative pressure patient rooms. Specific examples of engineering controls include ventilated tents, or enclosures that cover patients’ heads or upper bodies. These enclosures are used to draw exhaled air from the patient into a HEPA filter, decreasing healthcare workers’ exposure risks to patient-generated aerosols.  Healthcare organizations are reorganizing patient care areas to cohort COVID-19 patients by unit assignments and air handling systems. This separation enables non-COVID-19 departments (neurology, cardiology, oncology, and so on) and other patients to be isolated from COVID-19 patients and from the HVAC units serving COVID-19 patient units. Our greatest contribution as IHs in a pandemic can be through assisting healthcare in employing this hierarchy by reviewing, implementing, and confirming the effectiveness of engineering, administrative, and PPE controls. Of course, determining the most appropriate and effective engineering, administrative, and PPE controls requires a team effort, including, at a minimum, personnel from multiple departments such as facilities operations, safety, infection prevention, industrial hygiene, medical/nursing, and contractors. The infection preventionist and the industrial hygienist may characterize and address airborne infectious agents differently, but we are both working toward the same goal: protecting healthcare workers to the best of our abilities. IS THERE A CURRENT BEST PRACTICE FOR REMOVING OR INACTIVATING AIRBORNE VIRUSES USING HVAC SYSTEMS? STEVE WELTY: A March 26 pre-published study of airborne sampling performed at the Nebraska Biocontainment Unit and the National Quarantine Unit identified airborne COVID-19 viruses in patient rooms, bathrooms, and in the hallways outside their rooms. Assuming that viruses can become airborne, how can COVID-19 be removed or inactivated? A 2003 bioterrorism paper in the Journal of Architectural Engineering demonstrated that a MERV 13 filter only captures 46 percent of influenza viruses, which are similar in size to coronavirus, while a MERV 16 filter captures 76 percent. The same study indicated that 5,000 microwatts per centimeter squared (µw/cm2) of ultraviolet light would sterilize 94.9 percent of influenza, and combining MERV 16 filters and 5,000 µw/cm2 of UV will capture or neutralize 98.8 percent of influenza. Another study conducted by the U.S. Department of Energy demonstrated that using HEPA filtration and 10,000 µw/cm2 of UV could achieve kill/sterilization rates approaching 99 percent. Assuming that the influenza virus can be used as a surrogate for COVID-19, and that the efficacy in these studies translates to effectiveness in actual application, the combination of high-efficiency filters and UV disinfection can be effective in removing or inactivating airborne viruses, including COVID-19. WHAT WAYS CAN “DISPOSABLE” RESPIRATORY PROTECTIVE  EQUIPMENT (RPE) BE CONSERVED DURING A PANDEMIC? ROB STRODE AND CHRISTINE KNEZEVICH: Conserving RPE is usually associated with limiting or specifying the use of available new respirators. Though personal protective equipment is at the bottom of the industrial hygiene hierarchy of controls, it provides healthcare personnel with additional protection when in the proximity of a communicable individual. However, the COVID-19 pandemic has resulted in a significant shortage of N95 respirators, the most prevalent and popular form of RPE. Reusable elastomeric and powered air-purifying respirators, as well as disposable P100, N100, P99, or N99 respirators, can be alternatives to the N95 when N95s are in short supply, but these respirators may not be available or affordable. Face shields, used in conjunction with respiratory protective equipment, provide a protective barrier to the eyes as well as to the respirator, conserving this limited resource. This situation has led to research into the decontamination and reuse of disposable respirators, specifically N95 filtering facepieces.  Methods of decontamination include chemical treatments such as vaporized hydrogen peroxide (VHP), ethylene oxide sterilization, ozone, and hypochlorite; and physical treatments such as ultraviolet germicidal irradiation (UVGI) and conventional and microwave ovens. Earlier studies focused on the possibility of decontamination and reuse, while additional studies have since confirmed the efficacy of N95 respirator decontamination. However, efficacy under testing conditions may not equate to effectiveness in real-world applications.  Depending on the method, decontamination can result in deteriorating respirator performance in protection and fit. Particle capture considerations for the filtering portion of the facepiece include electrostatic forces in addition to interception and impaction. In addition, the fit will be influenced by how the decontamination method affects the shape of the facepiece and the elasticity of the straps. Consideration also must be given to contamination on both sides of the facepiece, as wearer expiration may contaminate the facepiece interior with different microbes than are trapped on the facepiece exterior. Finally, residues from chemical decontamination methods can potentially result in adverse health effects or unacceptable odors for the post-decontamination respirator user. Overcoming these complexities in killing or inactivating microbes while maintaining the integrity of respirator components and worker health appears possible, and may be key to continued protection of healthcare workers during a pandemic response where there is a shortage of respirators.  WHAT PREPARATIONS SHOULD A BUSINESS UNDERTAKE WHEN PLANNING, RESPONDING TO, AND RECOVERING FROM THE COVID-19 PANDEMIC? STEPHEN DERMAN: Throughout these difficult months, while nations and communities throughout the world are coping with myriad challenges facing the healthcare system and their way of life, a paper published in March by the National Academy of Medicine described a series of methods and scenarios that deserve strong consideration in dealing with pandemics, specifically COVID-19.  These are psychologically and physically demanding times, and they will remain difficult as more people become seriously ill and die. Providers may need to decide which patients will be able to access limited medical equipment, medications, tests, and potentially medical facilities, including hospital beds, to keep them alive. Providers may become physically ill or psychologically stressed, rendering them incapable of providing care. Dwindling supplies of protective equipment such as respirators and medical equipment such as ventilators, in addition to the pandemic’s toll on personnel and resources, will require healthcare providers to make difficult decisions in order to provide lifesaving care to patients perceived to have the better likelihood of survival and palliative care to others. This “crisis standard of care” is practiced in military combat situations; unfortunately, it may become the standard of care in many of our communities and hospitals. Recent guidance on crisis standards of care is available from the National Academies. During these extenuating circumstances, as safety and health professionals continue to provide guidance on safe and healthful work practices, we may be called upon to assist with many functions outside our normal practice areas. These might include emergency/disaster planning and logistics, providing guidance on use or reuse of equipment, developing and overseeing decontamination and hygienic practices, identifying higher- and lower-priority staff and patient needs, identifying resources to assist with provider or patient care, as well as understanding and assisting with psychological first aid for overworked and stressed-out healthcare providers. These are times for us to utilize and enhance all of our technical, interpersonal, and human skills to help each other. CDC’s “Interim Guidance for Businesses and Employers to Plan and Respond to Coronavirus Disease 2019 (COVID-19)” and AIHA’s The Role of the Industrial Hygienist in a Pandemic are designed to assist businesses in coping with these issues. HOW DOES AN IH’S WORK PROCESS CHANGE DURING A PANDEMIC, AND WHAT CAN I DO TO BE MORE EFFECTIVE? DON ARCHIBALD: During a pandemic, IHs need to apply scientific principles to answer questions where little or no data or research is available. For example, what is an acceptable, inexpensive, and quick method to decontaminate N95 respirators for reuse? When you are confronted with a question like this, leverage the resources and information from professional organizations. It’s likely that other professionals are also trying to address the same question. Rapid flow of information and changing conditions lead to communication overloads and breakdowns, and misinformation. Use your professional and personal networks to help gather and understand information more quickly. Fact-check information using different sources to ensure the information reflects the conditions on the ground before making decisions. Pursue information rather than waiting for it to come to you. When making decisions, understand that there is no 90 percent (let alone 100 percent) solution in an emergency. A reasonable expectation is to provide enough good information or solutions to solve the most pressing issues, plan a path forward, and move in that direction. In a pandemic, there is never enough time. You need to prioritize tasks and set time aside to address them individually. Establish a rhythm for your work. For example, review your email messages two or three times during and at the end of the day. In between, tackle the most urgent task, giving yourself a set time limit to work through the issue, then move on to the next task. Take a personal break at regular intervals and then get back to your task list.  Recognize that chaos is a normal part of daily activities during a pandemic, and work around it. Expect different answers to the same question depending on when during the pandemic the question is asked. Expect increased stress levels during the pandemic. Recognize stress indicators and practice good coping mechanisms such as a balanced diet, regular exercise, dedicated personal time, and finding enjoyable and healthy distractions. WHAT EMERGENCY RESPONSE SKILL SETS CAN BE MOST VALUABLE TO AN INDUSTRIAL HYGIENIST RESPONDING TO THE COVID-19 PANDEMIC?  ERIC ESSWEIN: The same ones we used for SARS in 2003 and Ebola in 2014–2016: problem-solving, communication skills, and humility. Problem-solving is a skill set you use every day, but doing it in the face of escalating global uncertainty is very different. Regardless of your workplace, during this pandemic you’ll be asked (and tasked) to resolve problems outside the scope of your normal duties, in limited time, and under economic and logistical constraints. You’ll need to triage problems that you can solve yourself, those requiring a team effort (the majority), and those requiring swift elevation to upper management (without making it look like you are failing). You’ll need to know how and where to look for guidance and solutions developed by others either inside or outside your organization, and to evaluate their veracity. You’ll need to prioritize the most vexing issues, like assessing impact on workers, while balancing the interests of your organization with the resources at hand. You may be required to offer expert guidance on the implementation of multiple IH principles including the hierarchy of controls; make decisions on PPE usage when supplies are constrained; expediently develop new work procedures; conduct training; and assist in decisions regarding your business’s continuity of operations, all potentially on the same day (and often well into the night). Communication skills are critical, because it’s always about communication. You’ll be looked to for expert risk communication and guidance in decision-making in an environment of tremendous uncertainty. You’ll need to promptly and concisely communicate, verbally and in writing, while providing accurate information and knowing when to ask for further clarification. In a rapidly escalating pandemic, failed communications can be viewed as ineptitude. Regardless of whether humility is a personality trait or a learned skill, the admonition “check your ego at the door” holds relevance in a pandemic. You’ll be under tremendous pressure and stress compounded by extended work hours and fatigue. Even though you may be in a leadership position or have experience in pandemic responses, you won’t have all the answers. Remain open to other people’s ideas, perspectives, and opinions, and bear in mind the importance of staying within your area of practice and expertise. Response operations are always a team effort. Remember to share credit, as you’ll likely be working with the same people once the pandemic has abated.   STEPHEN DERMAN, CIH, FAIHA, is president and CEO of MediSHARE Environmental Health & Safety Services in Cupertino, California. ROB STRODE, MS, CIH, FAIHA, is the technical director of industrial hygiene Services at Chemistry & Industrial Hygiene, Inc. in Wheat Ridge, Colorado.  DON ARCHIBALD, CIH, CSP, is the OPFM safety group lead at the National Institute of Standards and Technology (NIST) in Boulder, Colorado.  ERIC ESSWEIN, MSPH, CIH, CIAQP, FAIHA, is CEO of Emeritus Health and Safety, LLC in Conifer, Colorado. CYNTHIA ELLWOOD, CIH, PhD, FAIHA, is principal industrial hygienist at Associates in Occupational + Environmental Health, LLC in Black Hawk, Colorado. CHRISTINE KNEZEVICH, CIH, is senior industrial hygienist in the bioenvironmental engineering flight at Wright Patterson AFB near Dayton, Ohio. STEVE WELTY, CIE, CAFS, LEED AP, is president of Green Clean Air in Reston, Virginia. Acknowledgements The Synergist thanks Stephen Derman and Rob Strode for coordinating this article and facilitating its publication. The authors thank John Koerner and Roberta Smith for their contributions to this article. Send feedback to The Synergist.
3M: “Disinfection of Filtering Facepiece Respirators” (PDF, March 2020). ABSA International: “Decontamination and Reuse of N95 Respirators with Hydrogen Peroxide Vapor to Address Worldwide Personal Protective Equipment Shortages During the SARS-CoV-2 (COVID-19) Pandemic” (2020). AIHA: The Role of an Industrial Hygienist in a Pandemic (May 2006). American Journal of Infection Control: “Lifting the Lid on Toilet Plume Aerosol: A Literature Review with Suggestions for Future Research” (March 2013). American Journal of Infection Control: “Impact of Multiple Consecutive Donnings on Filtering Facepiece Respirator Fit” (May 2012). American Journal of Infection Control: “Toilet Plume Aerosol Generation Rate and Environmental Contamination Following Bowl Water Inoculation with Clostridium difficile Spores” (May 2019). Annals of Occupational Hygiene: “Effectiveness of Three Decontamination Treatments against Influenza Virus Applied to Filtering Facepiece Respirators” (January 2012). Annals of Occupational Hygiene: “Evaluation of Five Decontamination Methods for Filtering Facepiece Respirators” (November 2009).  ASHRAE: “An Efficient Ventilation Configuration for Preventing Bioaerosol Exposures to Health Care Workers in Airborne Infection Isolation Rooms” (PDF, 2017). ASHRAE: “Negative Pressure Patient Room Options.” Battelle: “Final Report for Bioquell HPV Decontamination for Reuse of N95 Respirators” (PDF, July 2016). bioRxiv: “Aerodynamic Characteristics and RNA Concentration of SARS-CoV-2 Aerosol in Wuhan Hospitals during COVID-19 Outbreak” (March 2020). CDC: “Cleaning and Disinfection for Community Facilities” (2020). CDC: “Handwashing: Clean Hands Save Lives.” CDC: “Interim Guidance for Businesses and Employers to Plan and Respond to Coronavirus Disease 2019.” CDC: Morbidity and Mortality Weekly Report¸ “Guidelines for Preventing the Transmission of Mycobacterium tuberculosis in Health-Care Settings, 2005” (December 2005). CDC: “People Who Are at Higher Risk for Severe Illness” (2020). CDC: “Strategies for Optimizing the Supply of Facemasks” (2020). CDC: “Symptoms of Coronavirus” (2020). Clinical Infectious Diseases: “Severe Acute Respiratory Syndrome Beyond Amoy Gardens: Completing the Incomplete Legacy” (March 2014). CRC Press: Emerging Infectious Diseases and the Threat to Occupational Health in the U.S. and Canada by William Charney (2006). Journal of Applied Microbiology: “The Potential Spread of Infection Caused by Aerosol Contamination of Surfaces after Flushing a Domestic Toilet” (August 2005). Journal of Architectural Engineering: “Modeling Immune Building Systems for Bioterrorism Defense” (June 2003). Journal of Engineered Fibers and Fabrics: “Evaluation of Multiple (3-Cycle) Decontamination Processing for Filtering Facepiece Respirators” (PDF, 2010). Journal of Occupational and Environmental Hygiene: “Effects of Ultraviolet Germicidal Irradiation (UVGI) on N95 Respirator Filtration Performance and Structural Integrity” (August 2015). Journal of Occupational and Environmental Hygiene: “Impact of Three Biological Decontamination Methods on Filtering Facepiece Respirator Fit, Odor, Comfort, and Donning Ease” (June 2011). The Journal of Infectious Diseases: “Detection of Airborne Severe Acute Respiratory System (SARS) Coronavirus and Environmental Contamination in SARS Outbreak Units” (May 2005). MedRXiv: “Transmission Potential of SARS-CoV-2 in Viral Shedding Observed at the University of Nebraska Medical Center” (March 2020). Minnesota Department of Health: “Airborne Infectious Disease Management: Methods for Temporary Negative Pressure Isolation” (PDF). National Academies Press: “Rapid Expert Consultation on Crisis Standards of Care for the COVID-19 Pandemic” (March 2020). National Academy of Medicine: “Duty to Plan: Health Care, Crisis Standards of Care, and Novel Coronavirus SARS-CoV-2” (March 2020). Nebraska Medicine: “N95 Filtering Facemask Respirator Ultraviolet Germicidal Irradiation (UVGI) Process for Decontamination and Reuse” (PDF).

U.S. Department of Veterans Affairs: "Psychological First Aid (PFA) Manual."

The Wall Street Journal: “What the Nurses See: Bronx Hospital Reels as Coronavirus Swamps New York” (April 2020).

World Health Organization: “Psychological First Aid: Guide for Field Workers” (PDF, 2011). World Health Organization: “WHO Guidelines on Hand Hygiene in Health Care” (2009).

Although the print version of The Synergist indicated The IAQ Investigator's Guide, 3rd edition, was already published, it isn't quite ready yet. We will be sure to let readers know when the Guide is available for purchase in the AIHA Marketplace.
My apologies for the error.
- Ed Rutkowski, Synergist editor
Disadvantages of being unacclimatized:
  • Readily show signs of heat stress when exposed to hot environments.
  • Difficulty replacing all of the water lost in sweat.
  • Failure to replace the water lost will slow or prevent acclimatization.
Benefits of acclimatization:
  • Increased sweating efficiency (earlier onset of sweating, greater sweat production, and reduced electrolyte loss in sweat).
  • Stabilization of the circulation.
  • Work is performed with lower core temperature and heart rate.
  • Increased skin blood flow at a given core temperature.
Acclimatization plan:
  • Gradually increase exposure time in hot environmental conditions over a period of 7 to 14 days.
  • For new workers, the schedule should be no more than 20% of the usual duration of work in the hot environment on day 1 and a no more than 20% increase on each additional day.
  • For workers who have had previous experience with the job, the acclimatization regimen should be no more than 50% of the usual duration of work in the hot environment on day 1, 60% on day 2, 80% on day 3, and 100% on day 4.
  • The time required for non–physically fit individuals to develop acclimatization is about 50% greater than for the physically fit.
Level of acclimatization:
  • Relative to the initial level of physical fitness and the total heat stress experienced by the individual.
Maintaining acclimatization:
  • Can be maintained for a few days of non-heat exposure.
  • Absence from work in the heat for a week or more results in a significant loss in the beneficial adaptations leading to an increase likelihood of acute dehydration, illness, or fatigue.
  • Can be regained in 2 to 3 days upon return to a hot job.
  • Appears to be better maintained by those who are physically fit.
  • Seasonal shifts in temperatures may result in difficulties.
  • Working in hot, humid environments provides adaptive benefits that also apply in hot, desert environments, and vice versa.
  • Air conditioning will not affect acclimatization.
Acclimatization in Workers