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Man Sneezing into tissue

NIOSH Activities: Respiratory Protection Research

The following are example NIOSH research projects that focus on various issues which affect the use of filtering facepiece respirators.

Reusability of Filtering Facepiece Respirators

General Description: This project focuses on the reusability of filtering facepiece respirators by conducting laboratory studies to understand: (1) how well decontamination methods work, (2) how decontamination methods on filtering facepiece respirators affect performance, and (3) the risks that can happen when handling a respirator contaminated with virus.

Relevance to worker safety and health: Findings from this research may be used by NIOSH and CDC to develop scientific recommendations on personal respiratory protection for healthcare workers, emergency responders, and the public. These studies may also be used by national and international standards development organizations to support new test methods.

Key Findings: Key findings of this project are found in the following peer-reviewed publications:

Status: Complete.

Point of Contact: CDC-INFO

Metabolic Evaluation of N95 Respirator Use with Surgical Masks

General Description: The Institute of Medicine has recommended the possibility that individual N95 respirators can be used for a longer time by covering the respirator with a surgical mask. This investigation compared using an N95 respirator with and without a surgical mask cover. It reports the potential effects on the wearer of the surgical mask overlay. These potential effects were assessed using an automated breathing and metabolic simulator instead of human subjects. Based on the results of this study, future investigations could include reconfiguring the simulator to mimic special needs populations.

Relevance to Worker Safety and Health: The Institute of Medicine recommendation responded to concerns that there may not be enough N95 particulate filtering respirators for the duration of an influenza pandemic. The recommendation was made without scientific evidence that this practice would have no important risk for the wearer.

Key Findings: Key findings of this project were published in the following manuscript:

Status: Complete.

Point of Contact: CDC-INFO

The Impact of Respirator Use on CO2 Levels and O2 Saturation

General Description: This project studies whether increased carbon dioxide retention and decreased oxygen saturation can reduce performance during long-term use of filtering facepiece respirators. Healthcare workers who wear filtering facepiece respirators to protect themselves from influenza may end up not breathing in enough oxygen and re-breathing too much carbon dioxide. This study evaluated the magnitude of these effects in subjects exercising on a treadmill at a predetermined exercise level.

Relevance to Worker Safety and Health: Healthcare workers who wear filtering facepiece respirators to protect themselves from influenza may have carbon dioxide and oxygen issues because of their respirator use. The carbon dioxide and oxygen issues may be worsened if a surgical facemask is worn as an overlay to prolong the useful life of the filtering facepiece respirators. Results from this study can be used by respirator manufacturers to improve their products, and consensus standards organizations can use the results to develop guidance documents with appropriate performance levels.

Key Findings: Key findings of this project are found in the following peer-reviewed NIOSH publications:

Status: Complete

Point of Contact: CDC-INFO

Respirator and Surgical Mask Efficacy From Cough Aerosols

General Description: Insufficient scientific studies have been completed showing how well surgical masks and respirators keep influenza from spreading to healthcare coworkers through patient coughs. Because of this, some experts disagree over what protection and how much of it is needed to adequately protect workers from this potential source of infection. This project measures how well surgical masks and disposable filtering facepiece respirators protect healthcare workers from infectious aerosols produced by patients during coughing. A cough aerosol exposure simulation system (cough simulator) produces a simulated aerosol-laden “cough” through a standard head form (“the coughing head form”). A second head form (“the breathing head form”) outfitted with a surgical mask or filtering facepiece respirator, such as an N95 respirator, is connected to a breathing machine to simulate a healthcare worker inhaling and exhaling. The coughing and breathing head forms are put in a test chamber to simulate patient coughing and nearby healthcare worker breathing.

Relevance to worker safety and health: This project provides enhanced scientific knowledge to develop appropriate workplace recommendations for healthcare workers based on the measured amount of the “cough” aerosol inhaled by the breathing head form with or without a surgical mask or respirator.

Key Findings: Key findings of this project are found in the following peer-reviewed NIOSH publications:

Status: Complete.

Point of Contact: CDC-INFO

Better Respirator Equipment Using Advanced Technologies for Healthcare Employees (Project BREATHE)

General Description: Healthcare workers may be required to wear respirators for a long time to protect themselves from some infectious diseases. Field studies have further reported that healthcare workers often comply poorly with recommended respiratory protection practices. Causes of poor compliance are complex, but users often report the design of the respirator causes discomfort and it is hard to use. To improve respirator compliance, Better Respirator Equipment Using Advanced Technologies for Healthcare Employees (Project BREATHE), was organized by NIOSH, working with the Department of Veterans Affairs and other partners to encourage that better respirators be developed for healthcare workers. Key phases in the project include (1) participating in a Project BREATHE interagency working group to identify the ideal characteristics of a respirator designed for healthcare workers, (2) developing clinically-validated respirator test methods, (3) promoting a voluntary consensus standard for a respirator designed for healthcare worker, and (4) developing and evaluating prototype respirator designs with new features that benefit healthcare workers.

Relevance to worker safety and health: Project BREATHE promotes developing more comfortable and usable respirators for healthcare workers, with a goal that health care workers will comply with recommended respirator policies and procedures.

Key Findings: Key findings of this project are found in the following peer-reviewed NIOSH publications:

Status: Complete.

Point of Contact: CDC-INFO

Development of Computer-Aided Face-Fit Evaluation Methods

General Description: This project develops computer-aided face-fit evaluation methods to better assess and improve the fit of respirators. This effort, through improved respiratory protection, seeks to reduce exposure to workplace airborne infectious agents. The project uses anthropometric studies to develop specifications for developing head forms and fit test panels that encompass facial dimensions that represent most all workers.

Relevance to Worker Safety and Health: Standards development organizations, such as the International Standards Organization (ISO), the American National Standards Institute (ANSI), the Food and Drug Administration (FDA), and NIOSH may use this knowledge and the products developed through this research as they set standards. Better standards will improve respirator fit and protection for workers.

Key Findings: Key findings of this project are found in the following peer-reviewed NIOSH publications:

Status: Completed

Point of Contact: CDC-INFO

Respiratory Protection Effectiveness Clinical Trial—Effectiveness Comparison of N95 Filtering Facepiece Respirators and Surgical Masks Against Influenza

General Description: The Respiratory Protection Effectiveness Clinical Trial (ResPECT) study involves NIOSH working with the CDC Office of Infectious Diseases, Department of Veterans Affairs (VA), Veterans Health Administration (VHA), and Johns Hopkins University. The project seeks to answer a key question about personal protective equipment (PPE) use: How well do N95 filtering facepiece respirators protect healthcare workers in an outpatient setting against influenza, influenza-like illness, acute respiratory illness, and other respiratory illnesses, as compared with surgical masks?

Relevance to worker safety and health: Control strategies are critical in limiting the spread of respiratory viruses such as influenza. Among non-pharmaceutical interventions for seasonal influenza, epidemic or pandemic respiratory illness, using surgical masks and NIOSH-certified N95 filtering facepiece respirators draws intense interest. However, their relative protective effect in clinical settings, especially in the outpatient setting, is unclear. The role of healthcare-associated spread in the 2003 severe acute respiratory syndrome (SARS) outbreak prompted evaluations that examined which interventions decreased spread of this respiratory virus among healthcare workers. Although data supported using respirators for procedures with a risk of extensive exposure to respiratory secretions, the need for respiratory protection outside of these settings was not adequately studied. Studies from epidemic respiratory virus season in the healthcare setting are missing, and recommendations for respiratory protection among healthcare workers are controversial. This study provides more research data needed to guide planning activities and policy makers. It will help public health groups and healthcare delivery organizations provide appropriate protection for healthcare workers during an influenza pandemic or other infectious disease epidemic.

Key Findings: A summary of the project can be found here:

Key Findings: John Hopkins Health System in Baltimore, MD, conducted the pilot study during the 2010–2011 influenza season. Subjects enrolled at four locations (six clusters) in the pilot study and were divided into two arms: filtering facepiece respirators and surgical mask. A total of 110 subjects completed the study, split evenly between the two arms. A total of 1 119 weekly and symptomatic nasal swab samples were analyzed for the presence of 17 respiratory viruses. The study was expanded to the VHA-New York Harbor Healthcare System and Denver Health/University of Colorado for the 2011–2012 influenza season. Data collection began in January 2012, with 663 subjects enrolled in 53 clusters across the three sites. About 1 400 nasal swabs were collected during the 2012–2013 influenza season. The study expanded to five cities in 2012–2013 by adding VHA hospitals in Washington, DC, and Houston, Texas. Additional clusters were added in Denver, including VHA and children’s hospitals, and they involved 1 185 subjects enrolled in 117 clusters. The 2012–2013 influenza season study yielded 2 722 nasal swabs from healthcare worker participants. During the influenza seasons from 2013–2015, seven sites were active, having 1 530 participants in the 2013–2014 influenza season and 1 840 participants in the 2014–2015 influenza season. For the 2013–2014 season, 3 436 nasal swabs were collected, with 4 073 collected for the 2014-2015 flu season. The pathogens detected in both symptomatic and asymptomatic swab samples include Influenza A, Influenza B, parainfluenza, adenovirus, coronavirus, metapneumovirus, respiratory syncytial virus, and rhinovirus. Researchers stopped collecting data after the 2014–2015 influenza season. Field sample analysis, and data processing, and manuscript writing continues.

Status: Complete.


Point of Contact: CDC-INFO

Why Hospital Staff Catch the Flu: Assessing Modes of Transmission

General Description: This project did a series of laboratory and field studies to better understand how influenza spreads in healthcare settings, including routes such as direct contact (such as fomite), inhalation, inspiration, and direct spray. Laboratory studies will look at how airborne influenza concentration relates to levels of personal protective equipment (PPE) contamination, and will be used to determine whether the PPE can be used as semi-quantitative “personal bioaerosol samplers.” Johns Hopkins University will conduct field studies to measure influenza exposures during patient care and to correlate that information with health outcomes from the companion Respiratory Protection Effectiveness Clinical Trial (ResPECT).  Control banding approaches will be assessed for respirator selection.

Relevance to worker safety and health: This study will help us better understand the modes of influenza transmission. Government agencies can use this information to address issues of appropriate protection for about 14 million healthcare workers in the United States. The data may also help public health officials pick non-pharmaceutical interventions to help keep seasonal and epidemic influenza from spreading among the public.
Assessing how infectious patients can contaminate PPE used by healthcare workers will help to discern the modes of transmission of influenza. This, in turn, will help in developing guidance (e.g., using control banding tools) for proper intervention and control. Assessing PPE contamination collected in the field during flu season, for which no published data exists, will help in assessing risks involving PPE reuse and cleaning during pandemic influenza, when PPE supplies will be scarce.

Key Findings: Our first findings focused on respirator reuse issues. Find more information on PPE and contamination in these NIOSH works:

Key findings: This project runs through September 2018. Laboratory research to assess how influenza aerosol sampling correlates to PPE contamination has been completed. This research will also improve protocols for extracting virus from PPE and shipping samples from the field site. A pilot field test at a Johns Hopkins University healthcare facility was done in February 2013. A more extensive field study was done in February 2015.  Work on control banding approaches will begin in 2017.

Status: Completed.

Point of Contact: CDC-INFO

Frequency of Fit Testing

General Description: The objectives of this project are to (1) assess how respirator fit changes over time for a subject wearing filtering-facepiece respirators, and (2) study the factors that affect the change.

Relevance to worker safety and health: Findings of this research may be included in standards, recommendations, and guidance documents issued by Occupational Safety and Health Administration (OSHA), California OSHA, International Organization for Standardization (ISO), American National Standards Institute (ANSI), Food and Drug Administration (FDA), and NIOSH. Other researchers will use the project’s work to begin new research into how often fit testing is performed. It will also be used by employers and safety professionals to implement appropriate OSHA-compliant respiratory protection programs, including fit testing performed often enough to improve safety.

Key Findings: Key findings of this project to date are found in the following manuscripts:

Status: Completed

Point of Contact: CDC-INFO

Physiological Evaluation of Tight- and Loose-Fitting PAPRs

General Description: The project evaluated the metabolic and respiratory responses of men and women who wore commercially available powered air purifying respirators (PAPRs) at rest and during three different exercise intensities on a treadmill. The project measured inhaled gas concentrations, pressures, and temperatures while the participants wore four different PAPRs at rest and during treadmill walking.

Relevance to worker safety and health: Findings of this research will be used in updated PAPR standards.

Key Findings: Key findings of this project to date are found in the following manuscript.

  • Sinkule EJ, Powell JB, Rubinstein EN, McWilliams L, Quinn T, Pugliese M (2016). Physiologic effects from using tight- and loose-fitting powered air-purifying respirators on inhaled gases, peak pressures, and inhalation temperatures during rest and exercise. Journal of the International Society for Respiratory Protection, 33(2): 36-52

Status: Additional data collection on two additional loose-fitting PAPRs was completed in FY17. Manuscript writing in progress.

Point of Contact: CDC-INFO

Evaluation of Stability of Stockpiled Respirators

General Description: N95 filtering facepiece respirators are commonly stockpiled for use in public health emergencies, including pandemics. Storage may affect how the respirator performs, allowing more particulate to penetrate than expected for an N95 filtering facepiece respirator. This project uses respirator tests and component material tests to develop models for predicting how well N95 filtering facepiece respirators protect after aging in storage. Results will guide stockpile planners and administrators.

Relevance to worker safety and health: Many who are involved in respirators and their selection will use the articles, guidance documents, and other work of the project. The information will benefit stockpile administrators; respirator manufacturers who are designing new respirators; researchers interested in respirators, aging of materials, or pandemic planning; and standards-setting organizations developing new respirator stability criteria.

Key Findings: None to date.

Status: Project peer-review is complete and data are being collected. This project will continue until September 2018.

Point of Contact: CDC-INFO

Monitoring Oxygen Saturation and Transcutaneous Carbon Dioxide Levels of Pregnant Workers Who Wear Protective Facemasks

General Description: This project studies the cardio-respiratory and physiological burden on pregnant working women who wear N95 filtering facepiece respirators during exercise.

Relevance to worker safety and health: Study findings, including publications and presentations at local, national and international meetings, will help government and public health agencies to make appropriate recommendations on how pregnant workers can use respiratory protective equipment. The project also offers other researchers data for use in further research on respiratory protective equipment.

Key Findings: Find project results in the following articles and NIOSH products (Science Blog and YouTube video).

Status: Completed

Point of Contact: CDC-INFO

Healthcare Surveillance—PPE Monitoring System

General Description: This project identifies standardized metrics reflecting current hospital policies, standards, and guidelines for respirator use. It considers how to harmonize data from sentinel hospitals to develop a national surveillance system for personal protective equipment (PPE).

Relevance to worker safety and health: Stakeholders will use project outputs to inform respirator guidance, to evaluate use and effectiveness of respirators in healthcare settings, and to create a model surveillance system that can adapt to additional personal protective equipment (PPE), hazards, and occupational sectors.

Key Findings: Key findings to date can be found in the following publications.

Status: A pilot project was completed starting with the respirator as the prototype PPE, healthcare as the first occupational sector, and airborne pathogens as the model hazard. In August 2015, Vanderbilt University received a 3-year contract to expand the current project to include Ebola PPE and to evaluate PPE monitoring across 15–20 hospitals. Work is on-going.

Point of Contact: CDC-INFO

Healthcare Worker Respirator Surveillance and Interventions

General Description: This project develops information products and resources to improve hospitals’ respiratory protection programs. It also reinforces to healthcare workers how to properly use respiratory protection to best protect against exposure to healthcare workplace inhalation hazards.

Relevance to worker safety and health: This project helps managers of respiratory protection programs in healthcare to better understand program requirements, so they can better prepare for future pandemics and respiratory pathogen outbreaks.

Key Findings: The National Personal Protective Technology Laboratory (NPPTL) recently finished developing a series of educational documents and training modules to help hospital manager’s design and implement effective respiratory protection programs. This reinforces to healthcare workers and students how to properly select and use respiratory protection. Findings can be found in these articles and NIOSH products:

Status: Next steps involve evaluating how hospitals use and adopt suggested strategies and resources for implementing respiratory protection programs and practices. Three pilot studies, “Does the Air Exhaled From A PAPR Wearer Contaminate the Sterile Field in an Operating Room”, “Pilot Study to Characterize Constituents of Surgical Smoke in the Breathing Zone of Surgical Personnel” and “Assessment of the Use of Reusable Respirators (Nonfiltering Facepiece Respirators) in Healthcare Organizations” are also underway.

Point of Contact: CDC-INFO

Assessment of Elastomeric Respirators in Healthcare Environments

General Description: The project evaluates how reusable respiratory protective devices (RPDs) are used in healthcare workplaces. It assesses successful strategies to overcome barriers to using reusable RPD, and it determines workplace practices that adopted these strategies.

Relevance to worker safety and health: Data taken from a large medical system respiratory protection program with many elastomeric device users will be used to inform methods to meet surge capacity demands for RPDs during public health emergencies. The project promotes use of alternative NIOSH-certified respirators.

Key Findings: None to date.

Status: Awarded in September 2014 to Stella Hines, University of Maryland


Point of Contact: CDC-INFO

Projectile Fluid Resistance and Flammability of Respirators and Other Head/Facial Personal Protective Equipment

General Description: This project develops improved tests for how synthetic biological fluid penetrates through clothing and respirator materials. Healthcare workers use respirators and other head/facial personal protective equipment (PPE) to protect against infectious microorganisms. A knowledge gap exists in fluid resistance and flammability of respirators and other head/facial PPE. Experiments will help researchers better understand the factors (such as projectile fluid direction, velocity and volume, surface tension and viscosity of the synthetic blood or body fluid, and rigidity of the PPE device) affecting how respirators and head/facial PPE resist fluid. Also planned are studies on the flammability of respirators and head/facial PPE.

Relevance to worker safety and health: Study findings can improve test methods for respirators and other types of PPE. NIOSH will use products, such as articles and presentations, to support improving the American Society for Testing and Materials ( ASTM) F1862 standard test method (for resistance of medical face masks to penetration by synthetic blood). The project’s research will also be used to support the CDC activities on emerging infectious disease transmissions.

Key Findings: Results of a pilot study have been published.

Status: A pilot study, “Fluid Resistance Properties of non-FDA cleared FFRs [filtering facepiece respirators]” has been completed. A new start was funded to continue the work. This project should be completed by September 2018.

Point of Contact: CDC-INFO