The Physiological Burden of Prolonged PPE Use on Healthcare Workers during Long Shifts

Posted on by Jon Williams, PhD; Jaclyn Krah Cichowicz, MA; Adam Hornbeck, MSN, APRN, FNP-BC, FNP-C; Jonisha Pollard, MS, CPE; and Jeffrey Snyder, MSN, CRNP

Healthcare workers (HCW) and first responders often work long, physically and mentally exhausting shifts as they provide care for patients, especially during a public health emergency. These long hours can result in fewer adequate breaks for personal care, nutrition, and hydration. During these extended work shifts, many HCWs are also required to wear personal protective equipment (PPE), which may include N95 filtering facepiece respirators (FFRs) elastomeric half-mask respirators, or powered air-supplied respirators (PAPRs). Particular features of PPE can impose a physiological (how the body normally functions) burden on the HCW which can be exacerbated by long work hours without adequate breaks for eating, hydration and self-care.

While every HCW should be medically cleared before wearing respiratory protection, there are still many factors that can exacerbate the PPE burden, including obesity, underlying respiratory conditions (asthma, allergies, COPD, etc.), and smoking. HCWs should be provided regular opportunities to take breaks and a supportive environment to report symptoms related to their PPE use. For example, using an FFR for an extended period may cause dizziness (as well as other symptoms), which could compromise the worker, workplace, and patient safety. Dizziness is an important warning sign, as it can be caused by dehydration, hyperventilation (gasping for breath), elevated carbon dioxide [CO2] levels in the blood, low blood sugar, and anxiety, among other things.

Respirator wearers should be aware of the potential physiological impact of using each type of respirator.

Filtering Facepiece Respirators

An N95 FFR user is always going to experience some level of difficulty breathing, or breathing resistance, even though these devices are designed to minimize breathing resistance as much as possible. Enough breathing resistance could result in a reduction in the frequency and depth of breathing, known as hypoventilation (the opposite of hyperventilation).

Hypoventilation is a primary cause of significant discomfort while wearing an N95 FFR (Williams 2010). However, studies done by Roberge et al. (2010) indicated that this hypoventilation did not pose a significant risk to healthcare workers over the course of less than one hour of continuous N95 use.  When HCWs are working longer hours without a break while continuously wearing an N95 FFR, blood CO2 levels may increase past the 1-hour mark, which could have a significant physiological effect on the wearer (Lim et al., 2006)*. Some of the known physiological effects of increased concentrations of CO2 include:

  1. Headache;
  2. Increased pressure inside the skull;
  3. Nervous system changes (e.g., increased pain threshold, reduction in cognition – altered judgement, decreased situational awareness, difficulty coordinating sensory or cognitive, abilities and motor activity, decreased visual acuity, widespread activation of the sympathetic nervous system that can oppose the direct effects of CO2 on the heart and blood vessels);
  4. Increased breathing frequency;
  5. Increased “work of breathing”, which is result of breathing through a filter medium;
  6. Cardiovascular effects (e.g., diminished cardiac contractility, vasodilation of peripheral blood vessels);
  7. Reduced tolerance to lighter workloads.

To fix the problem of breathing too much CO2 that has built up within the respirator facepiece, a worker can simply remove the respirator. Some facilities practice oxygen supplementation during these breaks from respirator use, but there really is no need for this as the oxygen in the environment is more than enough to relieve most of the symptoms listed above.

Elastomeric Respirators

The effects experienced with FFRs may also occur when wearing elastomeric half-mask respirators (EHMRs), which are a reusable type of respirator with a silicone facepiece and replaceable filter cartridges. Because they are reusable, EHMRs are a highly recommended alternative to the disposable N95 FFRs (Hines et al., 2019). However, the physiological burden on the wearer is more likely to cause anxiety when wearing an elastomeric respirator when compared to FFRs (Wu et al., 2011). The increased breathing resistances found in EHMRs can result in a decreased frequency of breathing and an increase in tidal volume (the air displaced between normal inhalation and exhalation).

In addition, studies have shown that using EHMRs with a greater resistance to breathing have resulted in the wearer breathing less oxygen (O2) and more CO2 (Roberge et al., 2010), which can cause elevated CO2 levels in the blood. The issues surrounding the use of elastomeric half-mask respirators in healthcare settings is discussed in further detail in a National Academies of Sciences report (Ref. 8).

Powered Air Purifying Respirators

Another reusable alternative to N95 FFRs is the Powered Air-Purifying respirator (PAPR). The physiological benefit of PAPRs is that they have a fan that blows fresh air through the filter; therefore, there should not necessarily be any sense of breathing resistance as experienced with an N95 FFR or an elastomeric respirator.  Because of this, wearing a PAPR would not cause either shortness of breath or hypoventilation, which may contribute to the increase in CO2 in the breathing space. However, there may be other psychophysiological (the way in which the mind and body interact) effects resulting from the constant noise produced by the PAPR motor, such as headache, distraction, anxiety, difficulty communicating with others in the room to mention a few.


Studies have shown that HCWs prefer wearing N95 FFR respirators to wearing elastomeric half mask respirators or PAPRs when considering comfort and the ability to communicate, HCWs perceive EHMRs and PAPRs to provide greater protection in higher threat environments (e.g., during pandemics) and prefer these respirators to the N95 FFR in spite of the limitations of comfort and reduced ability to communicate. The limitations are tolerated for the purpose of greater perceived protection.

Tips for HCW Health Awareness


While workers must concentrate on their important job duties and the proper use of PPE for self-protection, they must also be aware of the impact of PPE on their wellbeing. The balance between the protection afforded by PPE and the burden of that PPE must be met with a plan to mitigate the burden.

Take scheduled breaks

Find a safe place to properly take off the respirator to reduce CO2 build-up and the negative physiological effects associated with it.

Breaks during work shifts are vital to worker health and safety. The potential physiological burden brought on by PPE use can be an unfortunate side effect; however, it can easily be remedied with a little fresh air and proper self-care.

Hydrate and eat

Dehydration can be a significant problem when wearing PPE while working in high threat environments. The effects of dehydration may contribute to the experience of the physiological burden such as headache, dizziness, strong sensation of thirst, and reduced cognition or greater distraction from the job. Therefore, HCWs must be aware of the need for proper hydration especially if wearing PPE causes significant sweating from heat exposure. A rule of thumb is to drink 1 ml or 1 oz of fluid for every 1 ml or 1 oz of body weight lost. For example, if the HCW has lost 1lb of body weight they must drink 16 oz of fluid (or for metric, if the HCW has lost 1 kg of body weight, then they must consume 1000 ml of fluid to make up for the loss).

Similarly, one must eat healthy food in part because the calories are needed to provide energy for HCWs to continue their work and also because most food contains water which will help with re-hydrating the body.

Institute policies to care for employees

Supervisors and hospital management can minimize the physiological burden of PPE by instituting policies and procedures to assure breaks for HCWs, encouraging front-line supervisors to check in regularly with staff to assess for symptoms or concerns, and providing a mechanism to report symptoms immediately and without fear of penalty.


Warren (Jon) Williams, PhD is a research physiologist in the NIOSH National Personal Protective Technology Laboratory Research Branch

Jaclyn Krah Cichowicz, MA, is a health communications specialist in the NIOSH National Personal Protective Technology Laboratory Research Branch

Adam Hornbeck, MSN, APRN, FNP-BC, FNP-C is a nurse practitioner in the NIOSH National Personal Protective Technology Laboratory Research Branch

Jonisha Pollard, MS, CPE, is a team leader in the NIOSH National Personal Protective Technology Laboratory Research Branch

Jeffrey Snyder, MSN, CRNP is a nurse practitioner in the NIOSH National Personal Protective Technology Laboratory Research Branch

*Text edited for clarity


Other blogs on the effects of prolonged PPE use on healthcare workers include:

Skin Irritation from Prolonged Use of Tight-Fitting Respirators

Heat Stress Imposed by PPE Worn in Hot and Humid Environments


  1. Williams WJ. Physiological response to alterations in [O2] and [CO2]: relevance to respiratory protective devices. J Intl Soc Resp Protect 2010; 27(1):27-51.
  2. Roberge RJ, Coca A, Williams WJ, Palmiero AJ, Powell JB.  Physiological impact of filtering facepiece respirators (“N95 Masks”) on healthcare workers. Respiratory Care; 55(5):569-577, 2010.
  3. Lumb, AB. Changes in the carbon dioxide partial pressure. In:  Lumb, AB (ed.) Nunn’s Applied Respiratory Physiology, Seventh Edition, Churchill, Livingstone Elsevier, Edinburgh, pp. 355-361, 2010.
  4. Psycho-physiological effects.  Technical Specification Part 6: Respiratory Protective Devices – Human Factors (1st Edition 2014). Reference number: ISO/TS 16976-6 06:2014 (E).
  5. CDC Blog on Fatigue in Healthcare Workers.
  7. Disease Control and Prevention, National Institute for Occupational Safety and Health, DHHS (NIOSH) Publication 2016-106.
  8. Reusable Elastomeric Respirators in Health Care Considerations for Routine and Surge Use National Academies of Sciences, Engineering, and Medicine; Health and Medicine Division; Board on Health Sciences Policy; Committee on the Use of Elastomeric Respirators in Health Care. Editors: Catharyn T. Liverman, Olivia C. Yost, Bonnie M. E. Rogers, and Linda Hawes Clever. Washington (DC): National Academies Press (US); 2018 Dec 6
  9. Wu S, Harber P, Yun D, Bansal S, Li Y, Santiago S. Anxiety during respirator use: Comparison of two respirator types. Journal of Occupational and Environmental Hygiene. 2011;8(3):123–128.
  10. Lim ECH, Seet RCS, Lee KH, Wilder-Smith EPV, Chuah BYS, Ong BKC. Headaches and the N95 face-mask amongst healthcare providers. Acta Neurologica Scandinavica. 2006;113(3):199–202
  11. Patel PM, Patel HH, Roth DM. General Anesthetics and Therapeutic Gases. In: Brunton LL, Chabner BA, Knollmann BC (Eds) Goodman & Gilman’s Pharmacological Basis of Therapeutics, 12th Edition, McGraw Hill Medical, New York, pp.557-558, 2011.
  12. Hines S, Brown C, Oliver M, Gucer P, Frisch M, Hogan R, Roth T, Chang J, McDiarmid M. User acceptance of reusable respirators in health care. Am J Infect Contr. 47:648-655, 2019.


Posted on by Jon Williams, PhD; Jaclyn Krah Cichowicz, MA; Adam Hornbeck, MSN, APRN, FNP-BC, FNP-C; Jonisha Pollard, MS, CPE; and Jeffrey Snyder, MSN, CRNP

32 comments on “The Physiological Burden of Prolonged PPE Use on Healthcare Workers during Long Shifts”

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 ».

    It should be noted that the finding that elastomeric respirator use may result in the wearer breathing less oxygen (O2) and more CO2 is also found in N95 use. This is not isolated to elastomeric respirators and has been reported in Roberge 2010 (reference 2).

    In the construction industry we frequently use N95 respirators for dust and particulate protection. We learned long ago that people get more tired when they work while wearing a respirator. As PPE is the third line of defense we rely more on Engineering and Administrative controls.

    Very informative and interesting essay. Totally agree that Engineering and administrative control should be considered. The balance between manpower shortage and long duty hours is really a challenge.

    Thanks for writing on the physiological burden of prolonged PPE use on healthcare workers. There is also a mental health burden component as healthcare workers with PPEs may not feel the connection with the patients and patients without seeing the healthcare workers’ facial expression will feel alienated, worried and may become non-compliant to directions. It will be good if someone can cover that not any less important issue here.

    Very good summary, however I came across this the following in a 3M FAQ:
    “Does carbon dioxide from exhaled breath affect health?”
    “Carbon dioxide from exhaled breath inside of certified filtering facepiece respirator has not been shown to affect health. A 2010 study indicated that although CO2 levels increase inside filtering facepiece respirators (such as N95s) during wear, health indicates do not change significantly, suggesting that there is no effect on health.”
    Williams et al. (2010) Physiological response to alteration of O2 and CO2-relevance to RPD. J Intl Soc Respiratory Protection. 11:269-281

    “When HCWs are working longer hours without a break while continuously wearing an N95 FFR, CO2 may accumulate in the breathing space inside of the respirator and continuously increase past the 1-hour mark, which could have a significant physiological effect on the wearer (Lim et al., 2006)”.
    Lim does not make this conclusion! PCO2 was not measured in his study.[unsupported accusation removed per comment policy].
    Please provide me with adequate, peer reviewed literature which demonstrates that face mask wearing has been shown to result in an accumulation of CO2 …or withdraw this statement, which I believe to be erroneous.

    The CO2 issue is well documented in the Roberge et al. 2010 citation. We have made a minor edit above to address your comment with the Lim reference. We would like to emphasize that an increase in CO2 does not make wearing a mask problematic–it may provoke some symptoms in some people that might be uncomfortable. As was pointed out in the blog, the solution is to remove the mask in a safe place and breathe normally for a few minutes to exhale the extra CO2.

    Thank you for your comment. Please note that that health care workers activity levels are typically ~3 METs – so a somewhat lower exercise intensity than what is described in the article. However, the CO2 measurements in the respirator with and without speech are relevant to health care workers.

    A facility recently required a mask to be worn at all times in the plant with a minimum requirement of a surgical mask or cloth mask up to a KN95 or N95 except at break times. I would like to know: how often should breaks be provided as preventative measures from the side effects of prolonged PPE use?

    Breaks are non-existent in my wife’s ICU. Which is at a magnet, tier one hospital. They are all having serious health issues because of this idiocy.

    It is difficult to answer this question without specific information about the facility and the nature of the work being done there. If the wearer is not doing physically strenuous work then the person can wear the mask for hours. Surgeons and operating room staff often wear their masks for hours during surgical procedures without any issues. In one study (Roberge et al., 2010) subjects wore N95s and walked on a treadmill for about an hour with no adverse effects. However, some individuals may have different responses. If workers are performing a lot of physical work then the mask could get harder to wear in less than one hour. Additionally, when working in hot environments there are some specific work-rest schedules recommended. See:

    In response to Jon Williams’s comment. Operating rooms maintains a positive pressure environment so even though the percent concentration of oxygen remains the same as outside air, there are more total number of oxygen molecules per volume. So it’s like going from high altitudes to sea level and feel like though it’s much easier to breathe and often athletes can workout longer even though the percent oxygen concentration has not changed. Also, I’m assuming that Jon is referring to this study where the study found that “the dead space oxygen and carbon dioxide levels did not meet the Occupational Safety and Health Administration’s ambient workplace standards” and that two out of ten (20%) test subjects “had peak P(CO2) > or = 50 mm Hg” (normal is 35 to 45mm Hg). The subjects were walking “at 1.7 miles/h, and at 2.5 miles/h” which are lower than the average walking speed of 3 to 4 miles per hour.

    Thanks for your comment. The amount of negative pressure required for a negative-pressure operating room is actually negligible with respect to oxygen concentration, a fraction of a percent. The negative pressure test commonly used by HVAC engineers is to see the direction the flow deflects a small strip of tissue paper, or sometimes they use a smoke tube to visualize the air flow direction. If the pressure difference between inside the operating suite were even 1%, it would make it near impossible to open the doors to the room. A normal 2.5 x 7 foot door has 2,500 square inches of surface area. Since atmospheric pressure is 14.7 psi (pounds per square inch), a 1% negative pressure would be 0.15 psi and would require (0.15 psi) x (2500 square inch) = 375 lbs of force to open.

    The CO2 issue is well documented in the Roberge et al. 2010 citation. We would like to emphasize that an increase in CO2 does not make wearing a mask problematic–it may provoke some symptoms in some people that might be uncomfortable. As was pointed out in the blog, the solution is to remove the mask in a safe place and breathe normally for a few minutes to exhale the extra CO2.

    Regardless of what any of these studies say… I have been wearing a mask at the hospital since March , 13 hours a day non -stop for 3 shifts a week. I will say that in the beginning I was able to tolerate wearing it all day and be ok. Now it is to the point of looking for another job. After wearing it for an hour I feel terrible and must find a place I can take it off to breathe, which is looked on unfavorably as we are suppose to be compliant.
    I feel awful when I get home, unrelenting headache, exhaustion and constanly having to clear my throat all day. To my knowledge by researching OSHA; I do not believe any mask(N95 or surgical) was tested to be worn for that many hours all day for any person regardless of underlying conditions. Cloth masks were never tested by OSHA yet they recommend the general public wear them all day. In the beginning of the pandemic we wore PPE only in the patients room now its 24/7. There was less employee infection before this mandate at a time when the disease was more virulent in my opinion.

    Thank you for your comment. Even before the current pandemic, many workers performed job duties that required prolonged wearing of tight-fitting respirators, such as N95s, during their work shifts. For example, those working in industries involving silica, asbestos, or beryllium, may be required to wear respiratory protection for long durations. In healthcare, some complex surgeries have required physicians, nurses and others present to wear respirators and/or surgical masks for many hours. NIOSH conducted physiological burden studies from wearing PPE. In general, the findings were that physiological burden is typically low and should not be harmful, however periodically removing a respirator and other PPE is warranted, especially when working in hot or humid environments (high heat index) where heat stress can become an issue. The recommendations for public mask-wearing is one that is promoted by the CDC (, rather than by OSHA which focuses on worker safety and health.

    The symptoms you described, i.e., headache, exhaustion, and dry mouth, may be attributable to other causes besides wearing a respirator. We recommend that you may wish to consult your personal health care provider.

    Hospitals take every other bit of advice from the CDC. But will they act on this? Our workload and staffing does not permit hydration or relief. Our health is being adversely affected, and healthcare is our business- shouldn’t hospitals take better care if employees?

    Working as a dental hygienist, currently given same amount of patient time as before but with many more duties! We have a lunch break after 4 hours then work another 4 to 5 hours without break its terrible! We keep mask on at all times except lunch😳 a 1 hour lunch(hopefully) outside the building, no breaks its terrible!

    An observation I see is that the overwhelming number of studies regarding anything to do with masks, were/are done with health workers in mind. Performed in controlled settings and behaviors parallel to the healthcare sector. I feel that this “Science” is not applicable to the society environment, and we should stop using it as “proof” to support whatever argument we are invested in. Out here in society we do not have higher controls consistently in play, such as HEPA filtered ventilation for example. The efficiency of ANY PPE is highly dependent on training, quality condition of the item, and proper use of an item….none of which is happening out in society, anywhere, by anyone. The only consistent thing we have going is that the contaminated surface of our masks are being smeared all over our lips, nose, our chins, our pockets etc. It seems that for whatever benefit the mask might have achieved by wearing it, is completely negated by everything else we do with it. When are we going to get some science that is applicable to the actual environment variations, random health variations of people, physically exhausting working conditions, and general chaos that exists in the public setting? It feels like we are using Botany to fix a car battery issue, and being told its relevant because both things run on water.

    Thank you for your comment. Cloth or disposable masks are not considered personal protective equipment (PPE). Filtering facepiece respirators (FFRs) and powered air-purifying respirators (PAPRs) described in this blog are personal protective equipment (PPE) designed to protect the workplace wearer, both in healthcare and other industrial work settings. You are correct that prior to the current pandemic, research and the science was focused on occupational use of these products, and the efficiency to which they filter particles from the environment and reduce exposure from reaching the wearer.
    For the current situation, the public is being urged to wear masks, i.e., cloth or disposable paper masks that do not need to be fit tested, not respirators as described above. They are not being used to protect the wearer by filtering out particles from the air such as PPE does. Rather, these masks are worn as “source control,” protecting people around an infected mask-wearing person by capturing the mask-wearing person’s emissions during coughs, sneezes and/or speaking. It is important for everyone to wear a mask because persons without symptoms may be infected and emitting virus particles without knowing it; this is called asymptomatic spread. Wearing a mask may provide some protection to the wearer, but that is not its purpose. Proper use of cloth or disposable masks requires that they be discarded or cleaned after each use.

    Working as a dental hygienist, currently given same amount of patient time as before but with many more duties! We have a lunch break after 4 hours then work another 4 to 5 hours without break its terrible! We keep mask on at all times except lunch

    I am an older provider of psychiatric care in nursing homes and thus far survived many an outbreak. But I have a worsening chronic cough while wearing mask and during night without . I have never tested positive for covid 19. I don’t hear people talking about mask cough except from my coworkers. Is mask cough a thing?

    Thank you for your comment. We encourage you to see your primary care provider as a chronic cough should be evaluated. We are not familiar with “mask cough.”

    I come at the protection issue from an oral health viewpoint. The emergence of “Mask Mouth” can be directly linked to xerostomia (dry mouth) which results from dehydration. The cascade effect of dry mouth includes inflammation, sores, bacterial and fungal overgrowth (candida), gum disease, halitosis and caries. Dehydrated mucosa raises the risk of viral adhesion. The repetitive application of compounds formulated to deliver ongoing “mucoprotectant” benefits – enhanced saliva, mucosal hydration, antimicrobial cleansing – should be standard protocol for HCPs.

    I am a Grocery Clerk.My job is to talk with my customers while ringing them up,bag their groceries, run and get a price check if no one else is available,…and it is non- stop while wearing the mask.My mouth is raw, I feel sleepy and tired all the time after I get off work …and now we are being told we can’t have water bottles in the checkstand…How are we suppose to stay hydrated.

    Thanks for your comment. Employee access to water is a requirement under OSHA regulations: Lack of access to drinking water can cause dehydration. Your employer isn’t required to have water bottles at your workstation, but then other allowances (e.g., frequent breaks) are required. In regards to mask-wearing, the CDC recommendations for wearing a mask allow for intermittent removal of the mask when you are eating or drinking, then redonning the mask when not in the act of eating or drinking. While the mask is removed for eating and drinking, maintain social distance from others. Various possible adaptions are provided at

    hello , I am a heavy duty mechanic , I work in a mine in southern bc . the air quality is considerably good for the most part , however our organization is forcing us to wear the n95 mask for 12 consecutive hrs with only brakes to eat and once finished meal we are expected to wear this mask again, there are times when the shop is consumed with diesel smoke , welding and gouging fumes quite often, I have a heart condition and am on blood thiners aswell as other medications. I Am concerned for my heath wearing these masks , are my concerns valid. thank you for your time

    Sincerely Rene Grant

    Thanks for your comment. You ask if your concern is valid? The answer is that “it depends.” You described of conditions in the mine in British Columbia that, “…there are times when the shop is consumed with diesel smoke , welding and gouging fumes quite often…” The presence of diesel smoke and welding fumes could indicate the co-presence of carbon monoxide, nitrogen dioxide, and organic vapors. Another concern might be that the environment could be oxygen deficient due to the presence of combustion. The only way to know for sure if your environment is contaminated with these toxic gases, or if there is an oxygen deficiency if to have a qualified professional make measurement and assess the environment. The N-95 filtering facepieces mask you are using is only designed to remove particulates. If the toxic gases exceed their exposure limits, a respirator that offers greater protections such as a half- or full-facepiece elastomeric mask with a cartridge filter that removes particulates and the toxic gases might be required. If there is oxygen deficiency, a supplied air respirator may be required. In British Columbia, mines are regulated by The Ministry of Energy, Mines and Petroleum Resources is introducing centralized reporting for Dangerous Occurrences. They can be contacted at: Mine Incident Reporting Line 24/7 Phone: 1-888-348-0299 Email: Additionally, you may want to contact your personal health care provider to discuss your symptoms.

    I work in the film industry we were 12+ hours a day sometimes 67 days a week with a mask and a shield sometimes dirty as hell because you’re working with in the rain and mud construction debris old building debris and he gets really hard to breathe through these masks. I’ve been on anabiotic‘s and steroids for the last seven months because of infections in my face and throat and sinuses in the last two months I’ve developed heart failure because my heart won’t contract and pump the blood necessary in my left ventricle. Basically my breathing has changed to a heavy breathing out my mouth and then I’m constantly loss of breath now I’m back at work having to wear the same things and getting faint and dizzy all the time

    A requirement for wearing a respirator in an industrial (i.e., dirty) environment is that when a filtering facepiece respirator, such as an N-95, becomes soiled it should be disposed of and replaced with a new respirator. Increasing breathing resistance is a signal to the wearer that the mask should be replaced. Additionally, you may want to contact your personal health care provider to discuss your symptoms.

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