Evaluation of Surgical N95 Respirators Covered with Combinations of Masks and Face Shield

Details

• Personal Author:
  Powell JB ; Quinn T ; Simons J ; Walbert G
• Description:
  ABSTRACT: Limited availability of filtering facepiece respirators (FFRs) during extreme demand has prompted users to cover their N95 FFRs with another face covering to prevent surface contamination and extend its their useful life. PURPOSE: To evaluate the metabolic demands and internal breathing environments from covering an N95 with a surgical mask (SM), cloth mask (CM), and/or face shield (FS). METHODS: Three NIOSH-approved N95 models (cup (2) and trifold (1)) were evaluated as a control (N95 only) while covered under five conditions (SM, CM, FS, SM + FS, and CM + FS) using the NIOSH Automated Breathing and Metabolic Simulator. Every N95 was sealed to the Simulator head form for all trials. All conditions used one trial with each N95 for six incremental 5-minute work rates (oxygen consumption = 0.5, 1.0, 1.5, 2.0, 2.5, 3.0 liters per min STPD). Inhaled oxygen and carbon dioxide concentrations, peak inhaled and exhaled pressures, inhaled wet bulb and dry bulb temperatures were measured continuously and averaged across all work rates and covering conditions. Main effects of the six work rates, six covering conditions, and their interaction were examined using repeated measures ANOVA. Pairwise comparisons of the mean metabolic variable across all work rates were made between the N95 only to each covering condition. RESULTS: Significant omnibus main effects for work rate, covering condition, and interactions were found for all variables (p ≤ 0.01 for all). Table 1 presents the mean pairwise differences across all work rates between the N95 condition and each covering condition for all variables. CONCLUSIONS: Results suggest that metabolic demands and internal breathing environments are significantly impacted by all combinations of coverings tested when compared to N95 only. However, no differences observed were of large enough magnitude to be clinically concerning. It remains unclear if these differences would be perceived by wearers. [Description provided by NIOSH]
• Subjects:
  Communicable Diseases Occupational Health Personal Protective Equipment Respiratory Protective Devices Respiratory System Safety
• Keywords:
  Breathing Face Shields Infection Prevention Infectious Diseases N95 Filtering Facepiece Respirators Physiological Effects Surgical Masks
• ISSN:
  0195-9131
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  OSHA Region 3 ; Pennsylvania
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  NPPTL - National Personal Protective Technology Laboratory
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  54
• NIOSHTIC Number:
  nn:20066235
• Citation:
  Med Sci Sports Exerc 2022 Sep; 54(9S):662
• Federal Fiscal Year:
  2022
• Peer Reviewed:
  False
• Source Full Name:
  Medicine and Science in Sports and Exercise
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:33686955620c50e1d0e37571ca578b027d834df85b976c73727decffe15cdfe8775fe1e5b14e0a63b2a8d3706ff078fa9662030a7dfe2efe90725032a1df4ae4
• Download URL:
  https://stacks.cdc.gov/view/cdc/212720/cdc_212720_DS1.pdf
• File Type:
  [PDF - 394.38 KB ]