Respiratory Protection vs. Source Control – What’s the difference?

Posted on by Jaclyn Krah Cichowicz, MA; LCDR Megan Casey, RN, BSN, MPH; and Maryann M. D’Alessandro, PhD

In an effort to limit the spread of COVID-19, CDC recommends that adults and children two years and older wear a mask, especially when social distancing is not possible or feasible[1]. Cloth masks and medical masks used in healthcare settings (such as surgical or procedure masks) are important tools in the fight against the spread of COVID-19, however they are not a type of respiratory protection. Due to limited supplies, respiratory protection should be reserved for workers who rely on it to perform their work safely. The masks that we all should wear are primarily intended for source control. What is the difference between respiratory protection and source control?

Respiratory protection protects the wearer. Respiratory protection refers to respirators, which are protective devices that cover a person’s nose and mouth or the entire face or head to help reduce the wearer’s exposure from breathing in air that contains contaminants, such as small respiratory droplets from a person who has COVID-19. This type of protection can include filtering facepiece respirators (FFRs), like N95 respirators.

Source control protects others. Source control refers to the use of masks to cover a person’s mouth and nose and to help reduce the spread of large respiratory droplets to others when the person talks, sneezes, or coughs. This can help reduce the spread of SARS-CoV-2, the virus that causes COVID-19, by someone who is infected but does not know it.

Breaking Down the Difference

Photo © Shutterstock

Respiratory Protection: Respirators, such as the well-known N95 filtering facepiece respirator, remove particles from the inhaled airstream of the wearer through a filter media. When used in accordance with the manufacturer’s recommendations, respirators are highly effective at reducing the wearer’s exposure to bacteria and viruses, as well as other airborne particles like mold and dust, in their inhaled airstream. N95 filtering facepiece respirators are disposable devices that in times of normal operation, are discarded after every use or shift. There are key criteria for these personal protective devices to be effective as respiratory protection:

  1. The respirator filter needs to be highly effective at capturing particles that pass through the filter;
  2. The respirator must also fit the user’s face snugly to minimize the number of particles that bypass the filter and get into the breathing zone through gaps between the user’s skin and the respirator seal. A good seal helps ensure that the air goes through the filter.

When worn properly, respirators are designed to help protect the wearer by passing most of the air through the filter. N95 respirators filter at least 95% of particles of all sizes from inhaled air. The National Institute for Occupational Safety and Health (NIOSH) regulates respirators by using stringent test conditions to evaluate these devices, approving those that meet a minimum filtration efficiency requirement for occupational use.

It is important to note that a respirator that has earned NIOSH approval will have specific labeling printed on the facepiece. You may see some masks on the market labelled as “N95”, but if it does not contain the other components of the required label, most importantly the word “NIOSH,” it may not be NIOSH-approved and, therefore, cannot be relied on to provide respiratory protection. You can further ensure that you are using a NIOSH-approved respirator by checking for the model on the NIOSH Certified Equipment List or the NIOSH List of Approved Filtering Facepiece Respirators.

Additionally, if the respirator does not form a tight seal with the face, it cannot provide the expected level of protection. The Occupational Safety and Health Administration (OSHA) requires that workers are fit tested on the make and model of respirator that will be used, the first time it is used and every year after (or even sooner if the user has had a significant change in weight or change to their facial features, such as what might occur with extensive dental work). Fit testing ensures that respirator users are receiving the expected level of protection by minimizing contaminant leakage into the facepiece.


Preliminary data suggests that the outward leakage from exhalation valves is less than or comparable to that of many devices being used for source control (e.g., cloth masks, bandanas, surgical masks). However, until more research is available, masks with exhalation valves or vents should NOT be worn to help prevent the person wearing the mask from spreading COVID-19 to others (source control). Here are some tips when it comes to exhalation valves:

  • Wear a respirator without an exhalation valve when both source control and respiratory protection are required.
  • If only a respirator with an exhalation valve is available and source control is needed, cover the exhalation valve with a surgical mask or a cloth mask that does not interfere with the respirator fit. ​
Photo © Shutterstock

Source Control: Unlike respirators, masks are not designed to reduce the particles that the wearer will inhale and are not evaluated by NIOSH for their effectiveness to protect the wearer from airborne hazards. While there are many different mask designs available, they typically do not form the necessary seal against the wearer’s skin or have the appropriate level of filtration. Additionally, a typical mask wearer, outside of an occupational respiratory protection program, does not undergo fit testing to ensure an adequate level of protection. Therefore, while filtering facepiece respirators can be used as a type of source control (except those that have an exhalation valve in certain occupational settings), a mask should not be used as a respirator.

The purpose of wearing masks is to help reduce the spread of COVID-19 by reducing the spread of the virus through respiratory droplets from asymptomatic individuals. Masks are recommended as a barrier to help prevent large respiratory droplets from traveling into the air and onto other people when the person wearing the mask coughs, sneezes, talks, or raises their voice. Emerging evidence from clinical and laboratory studies shows that masks help reduce the spray of droplets when worn over the nose and mouth. Together with social distancing, masks are most likely to reduce the spread of COVID-19 when they are widely used by people in public settings.

While masks help to keep some large respiratory droplets contained and from reaching other people, they are not perfect. If you are sick with COVID-19 or think you might have COVID-19, wearing a mask does not make it safe or acceptable to visit public areas or be close to other people. Isolate yourself, whether or not you have symptoms. Stay home except when directed by your medical provider to get medical care. As much as possible, stay in a specific room and away from other people and pets in your home, use a separate bathroom if available, and do not share personal items like cups, towels or utensils. If you need to be around other people or animals within your own home, you should wear a mask, and be sure to frequently wash your hands. Those with underlying medical conditions who find it more difficult to breathe when wearing a mask can check with their health care provider to determine if a mask is appropriate for you. Masks should not be worn by children under the age of two or anyone who has trouble breathing, is unconscious, incapacitated, or otherwise unable to remove the mask without assistance.

A benefit of masks that are made from cloth material is that they can, and should, be washed after every use.


Should I Wear a Respirator?

The CDC does not recommend that the general public wear respirators to protect themselves from COVID-19. Due to the way SARS-CoV-2 spreads, the work duties of healthcare workers (e.g., directly caring for persons with suspected or known COVID-19), and possible supply shortages of respiratory protection, it is critical that those workers who need respiratory protection have it readily available to perform their work safely.

Additionally, the general public typically will not have undergone a fit test, therefore may not receive the expected level of protection from the respirator. Those required to wear respirators in the workplace must pass a medical evaluation to determine their fitness for wearing a respirator. However, a member of the general public may not have had such an evaluation, which may lead to complications for some people (e.g., those with underlying respiratory conditions) if they decide to wear a respirator.


A Note on Surgical Masks Used in Healthcare Settings

A surgical mask is a loose-fitting device that creates a physical barrier between the mouth and nose of the wearer and potential contaminants in the immediate environment. Surgical masks are regulated by the Food and Drug Administration (FDA) and are evaluated for their ability to protect the wearer from contact with liquids. Surgical masks are used as standard pieces of personal protective equipment in healthcare settings, including for COVID-19.

If worn properly, a surgical mask is meant to help block large-particle droplets, splashes, sprays, or splatter that may contain germs (viruses and bacteria), keeping it from reaching the wearer’s mouth and nose. Surgical masks also act as source control, just as any other mask. While they are evaluated by the FDA for their ability to protect against contact with liquids, surgical masks are not designed to filter or block very small particles from the air that the wearer is breathing. Unlike respirators, they do not provide complete protection because they do not form a tight seal against the wearer’s face.


Important Reminder

The best way to prevent COVID-19 illness is to avoid being exposed to this virus. In addition to wearing a mask, the CDC recommends everyday preventive actions, including staying home if you have been exposed or are sick, staying at least 6 feet apart from others, and hand hygiene in order to help prevent the spread of respiratory diseases.


Jaclyn Krah Cichowicz, MA, is a Health Communications Specialist in the in the NIOSH National Personal Protective Technology Laboratory.

LCDR Megan Casey, RN, BSN, MPH, is a Nurse Epidemiologist in the NIOSH National Personal Protective Technology Laboratory.

Maryann M. D’Alessandro, PhD, is the Director of the NIOSH National Personal Protective Technology Laboratory.


[1] Masks should NOT be worn by children under the age of 2 or anyone who has trouble breathing, is unconscious, incapacitated, or otherwise unable to remove the mask without assistance.

Posted on by Jaclyn Krah Cichowicz, MA; LCDR Megan Casey, RN, BSN, MPH; and Maryann M. D’Alessandro, PhD

26 comments on “Respiratory Protection vs. Source Control – What’s the difference?”

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 ».

    I have congestive heart failure and asthma. The extra resistance when wearing a mask immediately causes me breathing problems somewhat like the straw that broke the camels back. I am also a kidney transplant patient that takes immunosuppressant meds. No obesity but I am 67 yrs old.
    Maybe I’m supposed to wear a mask but I can’t because the mask causes breathing problems. Now what?
    Also I am not going to hid in my house.

    As stated in the blog, masks are recommended to help limit the spread of COVID-19. CDC recognizes that wearing masks may not be possible in every situation or for some people. Those with medical conditions should discuss options with their healthcare provider. Adaptations and alternatives can be considered to increase the feasibility of wearing a mask or to reduce the risk of COVID-19 spreading if it is not possible to wear one.

    Thank you for this great information! Does CDC have anything about use of surgical masks over exhalation valve with elastomeric respirator use in healthcare settings?

    Thank you for your comment. During severe shortages of personal protective equipment, when only a respirator with an exhalation valve is available and source control is needed, current CDC guidance recommends that healthcare workers can cover the exhalation valve with a surgical mask, procedure mask, or a cloth mask that does not interfere with the respirator fit. NIOSH is conducting studies to understand what is coming out of the exhalation valve to provide updated guidance based on the latest scientific data. As more information becomes available the guidance will be updated. More information on Elastomeric respirators can be found in our recent blog “Supplementing the Supply of N95s with Reusable Elastomeric Half Mask Respirators”

    Why isn’t any manufacturer making N95 Pleats Plus respirator? There used to be two sizes (S/M & M/L). Between these two sizes and after 20 years of fit testing, this respirator fit 98% of people be tween these tow sizes. Current [respirators] do not compare to the above.
    Unbelievable! Why did [company name removed] abandon these respirators when they purchased [company name removed], who used to produce these respirators? Healthcare facilities would not be scrambling to fit test healthcare workers of these were available. Disapointed

    Another note for infection prevention and control professionals to decide the correct isolation precautions for each patient who are served in the healthcare facility based on his signs and symptoms, to go with droplets or airborne isolation precautions

    Why is there no discussion of the immune system? It’s important for immune development to be exposed to germs and pathogens. Then, the immune system acts as a natural mask, doesn’t it? And why not just have a tissue and if you have to cough or sneeze, you can use the tissue and then dispose of it. Isn’t that better than carrying around the germs on your face? Finally, there is no evidence that healthy people (i., e. asymptomatic) can spread disease.

    Studies (including JAMA 2019 abstract) show little difference in HCP contracting influenza if they are wearing an N95 or a Level 3. Take away: N95 is one piece in the puzzle, and not the Holy Grail.

    Studies show the incidence of influenza in HCPs is the same with an N95 as it is with level 3 masks. I fear it may provide a false sense of security. I wear an N95 but am equally concerned about air changes per hour in my ops and office. I have also found an affordable air quality monitor ($300) to be very helpful in understanding and controlling the surrounding air. The N95 isn’t an end all, but should be a part of many redundant systems/techniques to decrease the chance of virus getting from one set of lungs into another.

    Thank you for your comment. While using alternate names or abbreviations may be helpful in some circumstances, it can add to confusion in others. The important thing is to understand the difference between respiratory protection and source control and the situations when these devices are needed.

    Has there been any discussion about adding an adapter to the the elastomeric respirator whereby another appropriate filter could be attached? This would effectively filter exhaled air without impacting the fit or functionality of the respirator. All filters could then be reused after disifecting or sanitizing for reuse as recommended by the CDC.

    NIOSH is working to identify solutions to address exhalation valve concerns in both filtering facepiece respirators and elastomeric half mask respirators (EHMR). Several research studies are underway on this issue.

    In parallel with the NIOSH research on exhalation valves, manufacturers have been conducting research and development to produce an elastomeric respirator that addresses the exhalation valve concerns.

    To this end, NIOSH has approved the first EHMR without an exhalation valve. This respirator is approved for use with either P95 or P100 particulate filters (NIOSH approval numbers: TC-84A-9260, TC-84A-9261, TC-84A-9256, TC-84A-9257). This EHMR can be used for both personal protection and source control. Exhalation is accomplished through the particulate filters meeting all NIOSH requirements, thereby allowing it to also serve as a means of source control since it will maintain the high level of filtration upon exhalation. This EHMR can be cleaned and disinfected as part of a respiratory protection program’s standard procedures. The particulate filters are available with an integrated splash guard to improve the ease of completing a user seal check, to help protect from liquids, and to aid in wiping down the filter housing with disinfectant.

    More information on NIOSH-approved respirators, including the first EHMR without an exhalation value, is available on the NIOSH Certified Equipment List.

    Is there any evidence that N95s worn by someone with COVID (i.e. a health care worker who didn’t realize they had COVID and later tested positive) protect others? i.e. do they provide better SOURCE control than a surgical mask? One would presume so, but I haven’t seen any studies that show this. Thanks

    NIOSH tested the filtration efficiency of N95 filtering facepiece respirators (FFRs) under reverse-flow conditions (i.e., in the direction of exhalation) ( Of the 13 models we tested, every model provided greater than 95% filtration efficiency of 0.35-micron particles regardless of inward or outward airflow. In other words, N95s FFRs appear to filter particles the same when breathing in or breathing out. Compared to surgical masks, N95 FFRs typically provide less outward leakage because FFRs are fit-tested whereas surgical masks often leak around the edges.
    Therefore, N95 FFRs should provide a greater reduction of emitted particles when compared to a surgical masks and therefore could be considered to afford greater protection as part of a source control strategy.

    “Exhalation is accomplished through the particulate filters meeting all NIOSH requirements, thereby allowing it to also serve as a means of source control since it will maintain the high level of filtration upon exhalation.”

    Does this mean that every NIOSH approved EHMR manufactured without an exhalation valve would always provide better source control than a surgical mask?

    Non-Valved, (i.e., no exhalation port) Particulate-Filtering Elastomeric Half Mask Respirators (NV EHMRs)

    “Every and always” is more than one can conclude without comparative testing and data on all known masks. However, NIOSH source control research on elastomeric respirators with and without exhalation valves is underway. CDC guidance regarding the types of masks and respirators you can use to protect yourself and others from getting and spreading COVID-19 is available here. These options include masks and N95 respirators.
    If you feel that you need respiratory protection in addition to source control, we recommend you consider a good-fitting, disposable N95 respirator for personal use. NIOSH-approved N95 respirators will filter 95% or more of particles of all sizes when they fit well and are worn properly, and in doing so, provide high level of protection for the wearer. In addition, NIOSH research has shown that disposable N95 respirators provide good source control. CDC’s Types of Masks and Respirators webpage provides more information on using N95 respirators including what to know about N95s, characteristics of NIOSH-approved N95s, restrictions for wearing N95s, and how to wear N95s.

    >>“Every and always” is more than one can conclude without comparative testing and data on all known masks.<< (1) There are very few EHMRs that do not have an exhalation valve a small enough number than can be tested (2) We know that an elastomeric mask of the correct size makes a much better seal to the face than FFRs. (My n95 FFR kept steaming up my glasses) It is easy to test the quality of the seal by holding one's hands over the filters while inhaling and exhaling. We know that P100 filters have 167-fold better filtration than an n95 filter: 99.97% compared to 95%. Then we know that a properly fit P100 EHMR without an exhalation valve must provide superior source control than an n95 FFR. Lets not allow the same tragedy that happened to Colin Powel happen to many more people. I am asking that the NIOSH approved EHMRs respirators without an exhalation valve be approved and recommended in health care settings for all those with severe immunodeficiency.

    Thanks for your comment. Any NIOSH approved respirators, including EHMRs without exhalation valves, can be used in health care settings for workers including those who have immunodeficiency, in conformance with the employers respiratory protection program. NIOSH has no authority to approve, recommend, or endorse the use of any particular respirator by patients or visitors to the health care setting. The health care facility may have its own infection control policies and procedures for patients and visitors and can insist that they wear a cloth mask, a surgical mask, or a respirator.

    For HCP, when is source control versus PPE required based on current CDC requirements? Can HCP wear a cloth face mask when not performing patient care?

    CDC provides Interim Infection Prevention and Control Recommendations for Healthcare Personnel During the Coronavirus Disease 2019 (COVID-19) Pandemic. Source control and physical distancing (when physical distancing is feasible and will not interfere with provision of care) are recommended for everyone in a healthcare setting. Source control options for HCP include:
    • A NIOSH-approved N95 or equivalent or higher-level respirator OR
    • A respirator approved under standards used in other countries that are similar to NIOSH-approved N95 filtering facepiece respirators (Note: These should not be used instead of a NIOSH-approved respirator when respiratory protection is indicated) OR
    • A well-fitting facemask.
    It should be noted that healthcare facilities may have their own policies and procedures with regard to source control. It is best to consult your facility’s Occupational Health Clinic or Infection Control staff for specific recommendations.

    I am an older adult at high risk for developing severe COVID-19. While I am not permitted to wear a mask, how can my risk of getting COVID-19 from a dentist or dental hygienist who has asymptomatic COVID-19 be minimized? What type of mask should the worker wear to maximize source control and my safety?

    When healthcare personnel wear respirators or well-fitting facemasks or cloth masks to prevent spread of respiratory secretions when they are breathing or talking, this is called source control. Any of the following source control options for healthcare personnel would be suitable:

    • A NIOSH-approved N95 or equivalent or higher-level respirator OR
    • A respirator approved under standards used in other countries that are similar to NIOSH-approved N95 filtering facepiece respirators (Note: These should not be used instead of a NIOSH-approved respirator when respiratory protection is indicated) OR
    • A well-fitting facemask.

    CDC recommends everyone stay up to date with COVID-19 vaccination to lower their risk of severe illness, hospitalization and death from COVID-19.


Post a Comment

Your email address will not be published. Required fields are marked *

All comments posted become a part of the public domain, and users are responsible for their comments. This is a moderated site and your comments will be reviewed before they are posted. Read more about our comment policy »

Page last reviewed: September 8, 2020
Page last updated: September 8, 2020