PPE CASE

Personal Protective Equipment Conformity Assessment Studies and Evaluations

Testing of Stockpiled ANSI/AAMI PB70 Level 3 Surgical Gowns 

To instill confidence in workers that personal protective equipment (PPE) will be effective, leaders in the PPE 

community develop performance standards and then check to see if the PPE meets these standards (i.e., 

conforms). This process involves a variety of public and private sector entities contributing expertise in the 

particular PPE and hazards. To bring greater oversight and coordination to these activities, the National Institute 

for Occupational Safety and Health (NIOSH) developed the National Framework for Personal Protective 

Equipment Conformity Assessment- Infrastructure.

The Framework assists leaders of the PPE community in developing 

activities that are appropriate given the risk posed to the worker. NIOSH 

works with public and private sector entities to assess and improve upon 

conformity assessment activities by collecting PPE from the marketplace or 

at the point of use. NIOSH then evaluates the PPE against established 

standards and uses the test results to provide leaders in the PPE community 

guidance on post-market sampling strategies, evidence-based criteria for 

PPE acceptance or rejection, and potential performance requirement 

updates. 

 

This report relates to work conducted at the request of the Centers for 

Disease Control and Prevention (CDC) Strategic National Stockpile (SNS). 

The SNS asked NIOSH to evaluate the performance of a model of surgical 

gown held in the SNS beyond the typical shelf life. Specifically, whether 

this gown model passed the Level 3 requirements of American National 

Standards Institute (ANSI)/Association for the Advancement of Medical 

Instrumentation (AAMI) PB70:2012, “Liquid Barrier Performance and 

Classification of Protective Apparel and Drapes Intended for Use in Health 

Care Facilities.” 

Keywords: PPE, surgical gowns, stockpile, control gowns, shelf life, ANSI/AAMI PB70

Abbreviations: 

ANSI/AAMI: American National Standards Institute/Association for the Advancement of Medical Instrumentation

AATCC: American Association of Textile Chemists and Colorists

ASQ: American Society for Quality

SNS: Strategic National Stockpile

RQL: Rejectable Quality Level

NIOSH did not find 

evidence that the 

stockpiled gowns tested no 

longer met AAMI PB70 

Level 3 requirements. 

However, only the 

manufacturer can set or 

extend the shelf life of 

their products. NIOSH 

does not recommend the 

use of these gowns without 

conducting representative 

testing of the stockpile and 

consulting with the 

manufacturer about the 

shelf life. 
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What NIOSH Did to Protect the Worker 

• At the request of the SNS, NIOSH evaluated one model of a Level 3 surgical gown from a single 

manufacturer to determine if the gown model, which was stockpiled beyond the typical shelf life, met 

the appropriate performance standards. The manufacturer indicated that the gowns, when originally 

purchased by the SNS, met ANSI/AAMI Liquid barrier performance and classification of protective 

apparel and drapes intended for use in health care facilities (ANSI/AAMI PB70:2012) Level 3

requirements. The test methods used were those specified for ANSI/AAMI PB70 (AAMI PB70 hereafter) 

Level 3 testing including AATCC 42: Water Resistance: Impact Penetration and AATCC 127 Water 

Resistance: Hydrostatic Pressure Test. 

o NIOSH received three sizes (marked on the package as L, XL, and XXL) of SNS stockpiled gowns 

(hereafter referred to as stockpile gowns) that were manufactured in 2008 and 2010 from three 

different lots. There was no expiration date provided on the labels, however all the gowns were 

beyond the typical shelf life (five years). NIOSH obtained a set of gowns manufactured in 2014 

from the open market for comparison (hereafter referred to as control gowns). Although this 

was the same model, visual inspection identified a different seam sealing technique. The 

stockpile gowns used a smaller weld area for the tie attachment and a welded sleeve seam, 

while the control gowns used a wide welded area for the tie attachment and fusible interfacing 

tape to form the sleeve seam. 

o NIOSH funded an accredited third-party testing laboratory to evaluate the gowns using the test 

methods identified in AAMI PB70: AATCC 42 Water Resistance: Impact Penetration on the 

critical zones and the front of the gown and AATCC 127 Hydrostatic Water Resistance on the 

critical zones. AATCC 42 subjects a test sample to a stream of water and measures the amount 

that penetrates through the fabric to a blotter paper. Garments that are more protective should 

have less water penetrating the fabric test sample (i.e., lower levels are better). AATCC 127 

applies water under pressure to one side of a fabric sample and determines the pressure at 

which droplets form on the other side of the sample. Garments that are more protective should 

be able to withstand higher levels of pressure before droplets form (i.e., higher levels are 

better). 

• The AAMI PB70 standard requires manufacturers to implement a quality system that rejects lots with a 

failure rate greater than or equal to 20% at least 90% of the time. This is known as the Rejectable 

Quality Level (RQL). NIOSH created a red/yellow/green stoplight analogy based on the RQL and levels of 

concern. Green is for instances where the failure rate of testing is below the RQL. Yellow is for 

intermediate failure rates, where more testing would likely be beneficial. Red is for instances where

failure rates are significantly higher than the RQL and indicates the gowns may not provide the expected 

level of protection. 
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For an evaluation of 32 gowns, NIOSH considered 0-6 failures as green, 7-9 failures as yellow, and 10 or 

more failures as red. 

What NIOSH Found Through Testing and Evaluation

NIOSH selected 12 XL gowns and 10 each of the L and XXL gowns for testing at each gown location specified in 

the AAMI PB70 Level 3 specification. The standard specifies that the AATCC 42 and AATCC 127 testing should be 

conducted at a location in the critical zones, which include the front of the gown (chest), the sleeve seam, and 

the points of the attachments. In addition, AATCC 42 should be conducted on the front of the gown, which may 

be outside of the critical zone chest area. 

• AATCC 42: Impact Penetration Test Method 

o All of the stockpile gowns passed AATCC 42 testing in all three critical zones, while one control 

gown failed at the tie attachment area. A single test failure should not be used to infer that a 

gown lot does not meet the AAMI PB70 standards, as the standard allows for some gown 

failures. All of the stockpile and control gowns passed AATCC 42 testing on the front of the 

gown.

• AATCC 127: Hydrostatic Pressure Test Method

o All test samples taken from the chest area of stockpile gowns passed the Hydrostatic Pressure 

Test criterion. At the sleeve seam zone, one stockpile gown failed out of 32 samples tested, 

while the control gowns (with a difference in sleeve seam design) resulted in 16 out of 32 

sample failures. According to the AAMI PB70 Rejectable Quality Limit (RQL), stockpile gowns did 

not exceed failure rates for any tested zones, while the control gown sleeve seam testing failed 

at a higher rate than the RQL. In contrast, stockpile gowns showed overall lower resistances for 

the tie attachment area than the control gowns. All control gowns passed while one stockpile 

gown failed for the tie attachment area.

Table 1. Red/Yellow/Green Criteria for Sets of 32 Samples at 20% RQL
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Set

Date of

Manufacture Size Sample Source Quantity 

Tested

Stoplight 

Conclusion

Stockpile gown-1 6/2008 XXL SNS 10 Green

Stockpile gown-2 1/2010 XL SNS 12 Green

Stockpile gown-3 1/2010 L SNS 10 Green

2014 control gown-1 8/2014 XXL Open Market 10 Red

2014 control gown-2 9/2014 XL Open Market 12 Red

2014 control gown-3 9/2014 L Open Market 10 Red

CASE Conclusion

NIOSH evaluated one model of SNS stockpiled Level 3 surgical gowns according to the requirements of AAMI 

PB70 liquid barrier classification standard for verification of adequate barrier performance in specified regions of 

the gown. Tests included AATCC 42 Water Resistance: Impact Penetration and AATCC 127 Hydrostatic Pressure 

Test. For AATCC 42 testing, all of the stockpile gowns passed the AAMI PB70 Level 3 criteria, while only one of 

the control gowns failed in the tie attachment region. During the AATCC 127 testing, the stockpile gowns 

showed a single failure each in a sleeve seam and in a tie attachment region out of 32 samples. The control 

gowns performed worse, with 16 out of 32 control gown samples failing the AATCC 127 testing on sleeve seams, 

while samples from the chest and tie attachment regions passed. Since the SNS stockpiled Level 3 gowns 

showed failure rates under the RQL, NIOSH gave green results for testing. However, the control gowns failed 

testing at a rate substantially higher than the RQL, thus NIOSH considered this a red result. 

This evaluation was limited to gowns selected from the lots received, so the conclusions cannot be generalized 

to state the readiness of the broader supply of Level 3 surgical gowns stockpiled in the SNS. In addition, NIOSH 

did not test other aspects of gown performance, such as tear strength or puncture resistance. NIOSH did not 

find evidence that the stockpiled gowns tested no longer met AAMI PB70 Level 3 requirements. However, only 

the manufacturer can set or extend the shelf life of their products. Thus, NIOSH does not recommend the use of 

these gowns without conducting representative testing of the stockpile and consulting with the manufacturer 

about the shelf life. 

Actions the PPE Community May Take to Further Protect Workers

• The control gowns manufactured in 2014 failed testing at a rate substantially higher than expected. 

NIOSH provided the results to the manufacturer and recommends additional research by the PPE 

community related to gown performance to better understand the factors that lead to test failures and 

the impact of test failures on healthcare worker safety and health.

Table 2. AAMI Level 3 Gown Lot Information and Results
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• AAMI PB70 was the only conformity-related classification standard that could be identified for surgical

gowns in the United States. However, this standard is designed for premarket conformity 

considerations. While the AAMI PB70 standard is not sufficient to identify pass or fail criteria for third 

party post-market product audits, it may provide a foundation for such a standard. For use as a postmarket standard, NIOSH makes the following recommendations:

o PPE Community: Request that the manufacturing process for surgical gowns meet existing 

quality standards. Additionally, request the shelf life information and recommended storage 

conditions.

o Standards Development Body: (1) Require full implementation of a standards compliant 

sampling plan, such the ASQ Z1.9 and Military (MIL)-STD-1916 currently mentioned in the AAMI 

PB70, to determine sampling plans; (2) develop a consensus-based standard for post-market 

conformity verification—i.e., for products on the market and being used by workers—taking into 

account time in storage and other factors likely to affect protection; and (3) make a requirement 

to include storage conditions and shelf life information on labeling or primary packaging.

Actions the PPE Users, Selectors, and Purchasers May Take to 

Further Protect Themselves and Others from Hazards

• Sign up for NPPTL’s Listserv at https://www.cdc.gov/niosh/npptl/sub-NPPTL.html to receive email 

notifications relevant to PPE. 

For more information related to personal protective equipment, visit the NPPTL website

https://www.cdc.gov/niosh/npptl 

To receive documents or other information about occupational safety and health topics, contact NIOSH:

Telephone: 1–800–CDC–INFO (1–800–232–4636)

TTY: 1–888–232–6348

CDC INFO: https://www.cdc.gov/cdc-info/ 

or visit the NIOSH website at https://www.cdc.gov/niosh/ 

For a monthly update on news at NIOSH, subscribe to NIOSH eNews by visiting 

https://www.cdc.gov/niosh/eNews/ 

Disclaimer 

Mention of any company or product does not constitute endorsement by the National Institute for Occupational Safety and 

Health (NIOSH). In addition, citations to websites external to NIOSH do not constitute NIOSH endorsement of the 

sponsoring organizations or their programs or products. Furthermore, NIOSH is not responsible for the content of these 

websites. All web addresses referenced in this document were accessible as of the publication date. 

Suggested Citation

NIOSH [2018]. PPE CASE: testing of stockpiled ANSI/AAMI PB70 level 3 surgical gowns. 

By Kilinc-Balci FS, Fries M, Rottach D, Shaffer R. Pittsburgh, PA: U.S. Department of 

Health and Human Services, Centers for Disease Control and Prevention, National 

Institute for Occupational Safety and Health, NPPTL Report Number P2018-0104.