H1N1: Protecting Healthcare Workers

Posted on by Maryann D'Alessandro, PhD, and Ed Fries

doctor examining patientAs we brace for the flu season, concerns are rising about the full impact of Novel H1N1 Influenza Virus (H1N1) also known as “Swine Flu.” As of July 31, 2009, there were 162,380 documented cases of human infection with H1N1 throughout the world, including the United States. As of August 6, 2009, there were 6,506 hospitalized cases and 436 deaths in the U.S. From the time of its emergence earlier this year, H1N1 has prompted a concerted response from health agencies here and abroad for the following reasons:

  • It is a never-before seen combination of human, swine, and avian influenza viruses.
  • It is being spread from human to human.
  • The age group most affected is healthy, young adults (unlike seasonal flu).
  • Like other influenza viruses, it continues to evolve.

Healthcare workers and emergency responders will face increased risk of exposure to H1N1 given their role in caring for sick patients. It is estimated that at lest 50% of ill people will seek medical care, and the number of hospitalizations and deaths will depend on the virulence of the pandemic virus. The National Institute for Occupational Safety and Health (NIOSH) is working to protect healthcare workers from exposure to H1N1 in the workplace. Examples of NIOSH initiatives related to H1N1 include communications strategies to emphasize the hierarchy of controls to reduce the risk of workers becoming ill, respirator research and enhanced respirator certification, laboratory and field research on the transmission of influenza, and plans for field evaluations and surveillance of healthcare worker and other populations.

This week, NIOSH researchers will participate in a workshop convened by an ad hoc committee of the Institute of Medicine. IOM describes the scope and purpose of the workshop in this way:

In response to a request from the Centers for Disease Control and Prevention and the Occupational Safety & Health Administration, an ad hoc committee of the Institute of Medicine (IOM) will conduct a study and issue a letter report to the CDC director and Assistant Secretary for Occupational Safety and Health by September 1, 2009. The committee will provide recommendations regarding the necessary personal protective equipment (PPE) for healthcare workers in their workplace against the novel influenza A (nH1N1) virus. Issues to be addressed to the extent feasible given available evidence and within the timeline for this letter report include: the potential for exposure to the nH1N1 virus among healthcare workers, which groups of workers are at risk, which patient care activities pose a risk of exposure and what degree of risk, and what is known and what is unknown about transmissibility, severity and virulence of the current virus and how transmissibility might change. The committee will base its recommendations on the available current state of scientific and empirical evidence about nH1N1 virus, as well its expert judgment. Economic and logistical considerations regarding PPE equipment will not be addressed in this letter report. In determining the appropriate PPE for the U.S. healthcare workforce, attention will be given to the current PPE guidance documents offered by the CDC and by the World Health Organization for novel H1N1 influenza and for seasonal influenza.

The IOM Workshop on Personal Protective Equipment for Healthcare Workers in the Workplace against Novel H1N1 Influenza A will be available via live audio webcast from 8 am to 5 pm on Wednesday, August 12th, and from 8 am to noon on Thursday, August 13th. The webcast can be accessed through the National Academies homepage. The full workshop agenda is available on the study’s website.

NIOSH experts will participate in the panel discussion on what is known about the effectiveness of respirators and surgical masks with regard to influenza virus or particles of a similar size to provide worker protection. NIOSH also will provide an update on research related to cough dispersion and exposure measures of influenza transmission, with an emphasis on a recent urgent care air sampling study. NIOSH also conducted an emergency room air sampling study last year.

The overall workshop goals include:

  • Examine the emerging science and clinical experience base associated with H1N1
  • Discuss criteria used to delineate infection control guidelines
  • Discuss criteria used to assess risk to the healthcare workforce
  • Examine what’s known about the effectiveness of medical masks, respirators, gowns, gloves, and eye protection in preventing H1N1 and seasonal influenza transmission

NIOSH would appreciate comments related to the workshop goals including peer-reviewed and published work on the topics mentioned above. We will forward comments received on this blog during the first week to the IOM to help inform their process. This is the first in a series of science blogs focusing on NIOSH initiatives related to H1N1. We welcome suggestions for future blogs on this topic.

Dr. D’Alessandro is the NIOSH PPT Program Coordinator and Associate Director for Science in the NIOSH National Personal Protective Technology Laboratory.

Mr. Fries serves as the Assistant Coordinator for the NIOSH PPT Program in the NIOSH National Personal Protective Technology Laboratory.

Posted on by Maryann D'Alessandro, PhD, and Ed Fries

54 comments on “H1N1: Protecting Healthcare Workers”

Comments listed below are posted by individuals not associated with CDC, unless otherwise stated. These comments do not represent the official views of CDC, and CDC does not guarantee that any information posted by individuals on this site is correct, and disclaims any liability for any loss or damage resulting from reliance on any such information. Read more about our comment policy ».

    1st Responders their equipment, including ambulances, stretchers etc will be contaminated with the infectious residue from the patient whether from sneezing, coughing or other bodily fluids. We need to isolate these patients and allow our 1st responders and their equipment to be immediately available for the next call.We also must provide a safe patient environment for immune compromised patients via some type of portable isolation systems. If we lose an ambulance or contaminate the ER where and how will the patient be transported, processed and treated. If there are 120 million flu patients the EMS structure will be taxed passed the breaking point,we have to minimize the exposure on the front end to protect the EMS personnel, patients and hospitals on the back end of the delivery and treatment system.

    Should all hospitals and doctor offices up thier cleaning crew in available numbers? Using protective equipment is a must. Keeping everything as clean as possible seems to be extremely important as well.

    Who is making sure the medical equipment being used such as ambulance and tranport equipment is being properly cleaned between patients? I work in a hospital and I dont feel the staff is properly trained for disinfecting thier equipment. Thier should be training for the transport teams. We provide the disinfectant but someone should train these drivers to disinfect properly. We have alot of differant companies come to our hospital and from what I have seen the ambulances are not cleaned at all.

    The CDC’s Interim Guidance for Emergency Medical Services (EMS) Systems and 9-1-1 Public Safety Answering Points (PSAPs) for Management of Patients with Confirmed or Suspected Swine-Origin Influenza A (H1N1) Infection offers “Interim Guidance for Cleaning EMS Transport Vehicles After Transporting a Suspected or Confirmed Swine-origin Influenza Patient” It states:

    “Routine cleaning with soap or detergent and water to remove soil and organic matter, followed by the proper use of disinfectants, are the basic components of effective environmental management of influenza. Reducing the number of influenza virus particles on a surface through these steps can reduce the chances of hand transfer of virus. Influenza viruses are susceptible to inactivation by a number of chemical disinfectants readily available from consumer and commercial sources.

    After the patient has been removed and prior to cleaning, the air within the vehicle may be exhausted by opening the doors and windows of the vehicle while the ventilation system is running. This should be done outdoors and away from pedestrian traffic. Routine cleaning methods should be employed throughout the vehicle and on non-disposable equipment.

    For additional detailed guidance on ambulance decontamination EMS personnel may refer to Interim Guidance for Cleaning Emergency Medical Service Transport Vehicles during an Influenza Pandemic. More general information about environmental persistence of influenza viruses and cleaning and disinfections measures can be found at:

    Hi folks,

    This is a critical issue for this country and my role in representing the New Zealand Accident Compensation Corporation.

    I would like to get as much information as possible. My own PhD was in the field of respiratory protection and I am also on the ISO physiological working groups on the issue.

    Because of the time differences between your country and mine it may not be possible to listen to the broadcasts albeit I will certainly try.

    Do you think there will be a written summary at some point in the future?

    Have a great day!

    Thank you for your comment and interest in this workshop.

    The PDF files of workshop presentations are posted as attachments on the following web page: http://www.iom.edu/CMS/3740/71769/71867.aspx. Also, the IOM will post audio files of the presentations after the workshop. A letter report is to be delivered to CDC and OSHA by September 1, 2009, with the committee’s recommendations.

    I am an industrial hygienist (and former Med Tech) that works for a federal agency in a bldg with over 700 people. We have one overworked nurse who’s primary duty is occupational medical surveillance and incidental first aid. I have seen no movement from our agency to address contamination prevention and decon. Our cleaning is done by Goodwill- Good people but their cleaning is barely enough for std hygiene requirements let alone a wave of flu and as a contracted agency they cannot do more than their contract. I would like to see guidance published such as removing public/shared reading materials from medical waiting rooms, a schedule of cleaning for waiting room hard surfaces, temporarily removing/covering upholstered chairs from waiting rooms, devising a separation of suspected flu patients from other first aid or wellness personnel and any other ideas that a working organization can do to address the first wave flu patients at their clinic. Or should we just let it all go as usual under the assumption that people are going to get the flu no matter what precautions are taken and this includes health care staff? The clinic sees these people before the ambulances so in essence the occ health clinic is the 1st stop in the chain of patient care. We have had great discussions but no answers.

    If respiratory hygiene is practiced as a standard precaution ALL of the time, and cleaning of equipment is followed as policy/procedure dictates, there is no more transmission of this flu than the seasonal flu. They are both flu viruses, and are the same size. The only special thing we have to do is follow the standard precaution rules no matter what the patient may have. We learned this during the SARS episode in Toronto, those people who followed precautions WITHOUT REGARD TO DIAGNOSIS did not contract the dreaded respiratory disease. The more the press concentrates on scaring people, the less our volunteers and employees listen to the basics, and the more illness we will have.

    Besides engineering and administrative controls, appropriate use of PPE (Personal protective equipment: masks, gloves, gowns) should be strengthened and becomes a priority. It is highly important to reduce the tansmision and to protect the health care workers.

    Good blog post. You have to feel for healthcare workers these days, as various protection methods are all coming to a head, such surgical masks vs. N95s and potential mandatory vaccinations (such as in NY state). It’s a lot to digest while still having to fulfill the primary duty of caring for patients.

    A very well written and informative blog that provided info that I never knew before. Thanks for the details as it gives me the opportunity to stay well informed on matters of this importance.

    P.S. The facts given full illustrate the need.

    Let us remember the role of ventilation in the spread of airborne microorganisms. I hope NIOSH is looking at ventilation rates to recommend and is measuring ventilation when outbreaks are investigated.

    As for respirators, if the strain has a high mortality rate I would not trust either a surgical or N95 filtering facepiece respirator. Only an elastomeric can be easily seal checked to be sure there is no leakage. If disposables are used, you need good fit-testing proceedures and continuous training. Unfortunely I have seen “fit testers” “make” the respirator fit on the HCW in order to pass the test, but the HCW could never replicate what the fit tester did later on.

    Good blog post. I recommand you see a french website. His team reports cases and compiles using data from official sources & news reports : [http://grippe-a-h1n1.over-blog.com/]

    We in South Africa as an Occupational Health Nurse Practitioner working at Public Sector, Tertiary OH and Safety Unit for the entire Province (Free State), my role is to ensure the health and safety of health care workers, if there is any need for us to be involved in research (my role)or training do not hasitate to contact me. I can be thankful if we can get assistance with those PPE as our province, Department of Health is in a bad financial state and we should be giving support to other government departments. Do send us information pamphlets or posters or any health promotion material.

    From the top of the lines to the bottom everyone is very important and we all need to know are jobs in-order to protect ourselves and our communities. Information is a key. We need to recieve and share all the information we can and make sure all policies are being followed. I think the key is our Infection Control Practiconers with everyone following all policies they set. Teamwork will help us all.

    As this is a “never-before seen combination of human, swine, and avian influenza viruses” and “It is being spread from human to human.””The age group most affected is healthy, young adults (unlike seasonal flu).”

    Is OSHA/NIOSH going to make/recognise H1N1 a reportable workplace injury for healthcare workers? If not why?

    NIOSH does not provide guidance on what is recordable on the OSHA 300 log. For questions regarding whether OSHA is going to make/recognize H1N1 a recordable workplace injury, please consult OSHA at 1-800-321-OSHA; Teletypewriter (TTY) number is 1-877-889-5627.

    To Wanda Kidd,
    I’m not sure what hospital you work in, but if you think the paramedics and EMT’s don’t know how to properly clean their equipment you are sadly mistaken.

    I work for a local chemical manufacturer and have been given a product to sell that can be used to sanitize via fogging thereby clean every surface in the area (door knobs, handles, keyboards, file cbinets, countertops, etc.)fogged. What do think about this tactic? Will it help? Is it neccessary?

    The process of fogging has been shown to be an effective mechanism for disseminating a liquid agent within a relatively quick timeframe and over a broad area. This technique has been used for the decontamination of a variety of biological agents within a confined environment. However, research has shown that there may be health risks for certain applicators of pesticide. It is important to note that the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA) requires that before selling or distributing a pesticide in the United States, a person or company must obtain registration, or license, from EPA. Before registering a new pesticide or new use for a registered pesticide, EPA must first ensure that the pesticide, when used according to label directions, can be used with a reasonable certainty of no harm to human health and without posing unreasonable risks to the environment. Therefore, registration is based on both the ability of the agent to inactivate the biological agent and the mode of application.

    Kenneth Martinez is the Deputy Director of the NIOSH Division of Surveillance, Hazard Evaluations, and Field Studies.

    Air travel made it possible for people to pass microorganisms quickly. SARS was spread through poor sanitation in a hotel in Hong Kong. If the proper quarantine measures were meant to prevent global contamination this epidemic could of been resolved quickly. But do governments and pharmaceutical companies not want spread of epidemics because big pharmaceutical companies make good money for vaccines.

    We have a very busy private pediatric practice in Columbia, SC. (17 pediatricians at 5 locations) Does anyone have any guidance on constructing clear barriers for the check-in and check-out staff? How high do they need to be?

    Thank you for your question. I am unaware of any construction guidance for transparent barriers such as those you describe. I’ve performed cursory checks through a handful of healthcare facility design references available to me and and have been unable to find crtieria in these as well. From an engineering perspective, I would advise construction of the barrier based upon the objective you were intending it to perform.

    If intended to prevent potentially contaminated air from entering the space occupied by the intake staff, then the wall/barrier combination should encompass a floor-to-ceiling partition, creating two distinct zones of space, with pressure relationships between the zones that establish the airflow direction from clean-to-dirty, towards the zone occupied by the potentially-contaminated patient. Any openings in the partition should be as small as is necessary to complete the intake activity while maintaining airflow in the clean-to-dirty direction.

    Note that you may need to obtain an experienced HVAC mechanic to adjust HVAC supply and exhaust airflows and create a slightly positive pressure within the “clean” worker area relative to that in the “dirty” patient area. If the barrier is only intended to prevent patient-generated droplets from spraying onto the intake staff or their working area, then the barrier need only be about a foot taller than the patient and slightly wider than the counter-opening where the patient would be seated/standing.

    Dr. Mead is a Senior Research Engineer in the NIOSH Division of Applied Research and Technology

    i am a hcw from so calif who is presently quarrantined @ home with pos h1n1. i work in icu predominately and have treated many pts with pos results. i have changed to hosp scrubs in lieu of taking my scrubs home to expose my family. very few hcws are doing this. recently our hospital has scaled back on N95 masks. we have heard these masks are costly. the us is running out of them and then finally they said th pt is now no longer testing pos for virus-although most of hcws cannot access this info. well i listened to them and ended up admitted in hospital. never as sick im 34 yrs in the hosp setting. any ideas -thanks

    This was a great article. Although I no longer work in the health care field I feel that this information is very beneficial to all, I’m sure the local nurse/admin in charge of policies at hospitals already have comparable plans in place.

    swin flu virus will be a very weak infront of us when only we take our necossary precautions againest this virus.

    The CDC’s Questions & Answers 2009 H1N1 Flu (“Swine Flu”) and You contains a “Contamination & Cleaning” section. Additionally, Interim Guidance on Environmental Management of Pandemic Influenza Virus can be found at Flu.gov and contains a Public Fact Sheet: Control of Pandemic Flu Virus on Environmental Surfaces in Homes and Public Places. More general information about environmental persistence of influenza viruses and cleaning and disinfections measures can be found at:

    My question pertains to vaccinating Healthcare workers with the H1N1 live vaccine. We treat HIV patients in our clinic and there is some concern that if we treat our health care workers, we will expose our HIV patients to the virus.

    We are not using the live virus with our HIV patients but would like to use it with our staff.

    The following information comes from the CDC – HIV/AIDS and the Flu MMWR: Prevention and Control of Influenza

    Use of inactivated influenza vaccine is preferred for vaccinating household members, health-care workers, and others who have close contact with severely immunosuppressed persons (e.g., patients with hematopoietic stem cell transplants) during those periods in which the immunosuppressed person requires care in a protective environment. The rationale for not using LAIV among health-care workers caring for such patients is the theoretical risk that a live, attenuated vaccine virus could be transmitted to the severely immunosuppressed person and cause disease. No preference exists for inactivated influenza vaccine use by health-care workers or other persons who have close contact with persons with lesser degrees of immunosuppression (e.g., persons with diabetes, persons with asthma taking corticosteroids, or persons infected with human immunodeficiency virus), and no preference exists for inactivated influenza vaccine use by health-care workers or other healthy persons aged 5–49 years in close contact with all other groups at high risk.

    John Decker, R.Ph., C.I.H., is the NIOSH Associate Director for Emergency Preparedness

    I’m a teacher in Central Illinois and the district I teach in just reported our first case of H1N1. What specific cleaning guidelines does the CDC recommend? We received a letter from our superintendent that said the CDC doesn’t recommend any additional cleaning. Why not?

    i am an occupational therapist working in the acute setting. i understand that i need to wear gloves, gowns, and N95 mask. do i need to wear goggles when i work with patients who are H1N1 positive? i am hearing mixed information on this. know that when i work with patients, i am in very close proximity to the patient. thanks.

    The following isolation precautions are recommended for healthcare personnel who are in close contact with patients with suspected or confirmed 2009 H1N1 influenza. For the purposes of this document, close contact is defined as working within 6 feet of the patient or entering into a small enclosed airspace shared with the patient (e.g., average patient room):

    From: Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings 2007
    Standard Precautions — For all patient care, use nonsterile gloves for any contact with potentially infectious material, followed by hand hygiene immediately after glove removal; use gowns along with eye protection for any activity that might generate splashes of respiratory secretions or other infectious material.

    Should we be vaccinating out-patient pediatric practitioners and nurses, who are seeing dozens of flu patients per day in addition to interacting with healthy young infants, pregnant moms and rounding on newborns in two hospitals? we outpatient pediatric providers are not currently on a priority list to receive vaccine, though urgent care and ER workers are, simply because they are seeing their sick patients within hospital walls. please clarify. thanks

    Just wanted to say great job with the blog, today is my first visit here and I’ve enjoyed reading your posts so far.

    What is the best way to disinfect computer keyboards against the spread of H1N1? We are a non-profit social service mental health agency with limited funding. We have approximately 150 employees and alot of them share computers.

    Ah!!! at last I found what I was looking for. Somtimes it takes so much effort to find even tiny useful piece of information.

    Nice post. Thanks

    H1N1 flu has had greater impact on blacks and Hispanics, But the findings are of relatively small sample sizes, health officials said. It will take much longer to get definitive data on swine flu’s racial impact. I believe everyone should get a flu shot except anyone who’s ever had a severe reaction to a flu vaccination, infants under 6 months old and anyone with a fever. If your child does need a flu shot, your pediatrician is the best place to start looking, but if they aren’t offering flu vaccine this year, you might check with your local health department, hospital, or pharmacies, and get one wherever you can.

    I am a bit confused by some of these comments and perhaps it bears correcting by an expert. There have been repeated comments disconnecting the Pandemic A (H1N1/09) from Severe Acute Respiratory (SARS) but I am under the impression that Influenza A is a respiratory ailment since it is classified as an adenovirus and that they are not mutually exclusive. In fact I have read that high mortality rate from H1N1/1918 were likely due to SARS and that this is the danger with this Pandemic. I think what they mean is the SARS which resulted from the Asian Avian Flu which was also an Influenza A and an adenovirus but H4N6.

    As I understand it, there is a possibility for this Pandemic to act like the Asian avian flu of 1999 because if it causes the “cytokine storm” or an over-stimulation of the immune system by these communicator cells, it could result in massive SARS… and the concern is that SARS of this type has a nearly 50% rate of mortality. If this is true I don’t think we are concerned enough or doing enough to protect ourselves.

    While both pH1N1 influenza and SARS lead to respiratory ailments, they are two distinctly different viruses that cause two different respiratory ailments, though they have some overlapping elements. Neither the SARS virus or influenza virus are adenoviruses, with influenza being a member of the orthomyxiviridae family, and the SARS virus being a coronovirus belonging to the Coronoviridae family.

    The high mortality rate due to the 1918 influenza pandemic was in part related to a reaction to the virus which resulted in a “cytokine storm” which led to a buildup of fluid in the lungs. This buildup of fluid was consistent with a condition known today as “Adult Respiratory Distress Syndrome,” or ARDS. This is a clinical condition which can have a wide variety of underlying causes. It should not be confused though with the four letter acronym SARS, which is a descriptive name for a new coronavirus which appeared in 2002, and which was given the name “Severe Acute Respiratory Syndrome” based on the nature of the illness which it sometimes caused. Both the 1918 influenza virus and the SARS virus were capable of leading to a condition known as ARDS. This condition (ARDS) has not been associated to any significant extent with the current 2009 pH1N1 influenza virus.

    LCDR John Halpin MD, MPH, is a Medical Epidemiologist in the NIOSH Emergency Preparedness and Response Office

    This is my first visit to your blog.
    Great article You have here on protecting health workers against H1N1.
    I will come back for more reference.
    Thanks for sharing.

    If respiratory hygiene is practiced as a standard precaution ALL of the time, and cleaning of equipment is followed as policy/procedure dictates, there should be no further transmission – or at least very little.

    I am an occupational therapist working in the acute setting. i understand that i need to wear gloves, gowns, and N95 mask. do i need to wear goggles when i work with patients who are H1N1 positive? i am hearing mixed information on this. know that when i work with patients, i am in very close proximity to the patient. Thanks.

    Thank you very much for the inquiry. Although we are providing the general response below, it would be wise for you discuss your specific situation with the infection control professional serving your healthcare facility.

    Current recommendations for personal protective equipment (PPE) use to prevent transmission of H1N1 are found in the CDC document, “Prevention Strategies for Seasonal Influenza in Healthcare Settings,” available at http://www.cdc.gov/flu/professionals/infectioncontrol/healthcaresettings.htm#recommendations. That document suggests use of “standard” and “droplet” precautions during routine patient care. Additional precautions, including the use of respiratory protection equivalent to a fitted N95 filtering facepiece respirator are recommended to be used in the setting of aerosol-generating procedures. Standard and droplet precautions are described in detail in the document “2007 Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings,” and are listed at http://www.cdc.gov/hicpac/2007IP/2007ip_part4.html#4.

    Eye protection is an issue that frequently comes up. The detailed description of standard precautions includes the following guidance:

    Use PPE to protect the mucous membranes of the eyes, nose and mouth during procedures and patient-care activities that are likely to generate splashes or sprays of blood, body fluids, secretions and excretions. Select masks, goggles, face shields, and combinations of each according to the need anticipated by the task performed…

    Thus, eye protection is a standard precaution that should be used in caring for any patient who creates body fluid sprays that might strike the mucous membranes, including patients who create sprays of respiratory or oral secretions by coughing or sneezing. Still, you may wish to know that although influenza eye infection (conjunctivitis) has previously occurred in association with avian influenza, ocular infection or transmission have not occurred in association with H1N1 influenza.

    I am interested in weather or not so called UV light devices mounted directly into the buildings HVAC ductwork have any effect on the h1n1 virus. I am referring to devices like this Phicell Light

    They claim to create some type of peroxide in the ductwork which kills viruses. Anyone with additional info or test results?

    Ultraviolet germicidal irradiation (UVGI), or the use of ultraviolet light to inactivate viruses, bacteria, and fungi, can be effective at inactivating influenza viruses, including the H1N1 strain. McDevitt et al. published one of the most recent peer-reviewed articles on inactivation of influenza with UVGI (McDevitt JJ, Rudnick SN, Radonovich LJ. Aerosol susceptibility of influenza virus to UVC light. Appl Environ Microbiol, 2012.).
    However, when using straight UVGI technologies, microbial inactivation only occurs when the organisms are within the direct or reflected UV irradiance zone. A UVGI fixture may require multiple lamps mounted in the air duct to provide inactivation of the influenza viruses that pass through the irradiated zone in the duct. The in-duct UVGI fixtures provide no inactivation for microorganisms that are not inside the irradiance zone.

    Manufacturers make many claims as to the effectiveness of their devices to eliminate VOCs and kill airborne or surface pathogens. These devices are rarely tested by independent, third-parties and the methodologies and results rarely appear in peer-reviewed, scientific literature.

    *Christopher Coffey is Acting Associate Director for Science in the NIOSH National Personal Protective Technology Laboratory.

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