NIOSH Conformity Assessment 

Notice

NIOSH CA 2021-1034R1

June 2021

Subject: Summarized Information about NIOSH Respirator Approval 

Program (i) Basic Application Procedures (ii) Quality Assurance 

Requirements and (iii) Supplier or Subcontractor Agreements

Supersedes: March 2021 version

Supersedes: April 7, 2005 Letter to All Manufacturers, Clarification of Supplier 

and Subcontractor Relationships

Supersedes: September 24, 2012 Letter to All Manufacturers, Respirator 

Sampling Procedures
Document Number

NIOSH CA 2021-1034R1

Page 2 of 19

1 SUMMARY

NIOSH requires approval holders to meet performance requirements and the respirators must be 

manufactured under a quality managementsystem (QMS) that isreviewed and accepted as part of 

the approval process. To keep NIOSH’s applicantsinformed about the respirator approval program, 

NIOSH is providing this document to clarify expectations related to (1) the basic application 

procedures; (2) the quality assurance (QA) requirements in the NIOSH regulation, 42 CFR Part 84, 

Subpart E; and (3) requirements for supplier and subcontractor agreements.

Throughout this document, applicant refers to an individual, partnership, company, corporation, 

association, or other organization that designs, manufactures, assembles, or controlsthe assembly 

of a respirator and who seeks to obtain a certificate of approval for such respirator. NIOSH 

considers domestic applicants to be those whose design/development activities, quality 

assurance activities, and manufacturing sites are located inside the United States. NIOSH 

considers applicants whose headquarters are located within the United States but whose 

design/development activities, quality assurance activities, and/or manufacturing sites are not 

within the United States to be non-domesticapplicants.

This guidance can assist applicants in navigating the NIOSH review process by better outlining the 

QA requirements in one document, because guidance is currently located in multiple documents. 

This document does not create any new requirements, although it does provide a new example of 

acceptable ways to present information to NIOSH for use in the QA review. This guidance is not a 

substitute for reviewing and understanding 42 CFR Part 84 or the NIOSH Standard Application

Procedure (SAP) relevant to the respiratory protective device that an applicant will submit to 

NIOSH for approval. The example provided is tailored for filtering facepiece respirators (FFRs), but 

this guidance can be used as a starting point for all applicants. Please consider all parts of this 

document.

Note: If an applicant has already submitted an application and determines, based on this guidance, 

that the application is not adequate, the applicant should submit a request to withdraw the

Subject: Summarized Information about NIOSH Respirator Approval 

Program (i) Basic Application Procedures (ii) Quality Assurance 

Requirements and (iii) Supplier or Subcontractor Agreements

Supersedes: March 2021 version

Supersedes: April 7, 2005 Letter to All Manufacturers, Clarification of Supplier 

and Subcontractor Relationships

Supersedes: September 24, 2012 Letter to All Manufacturers, Respirator 

Sampling Procedures
Document Number

NIOSH CA 2021-1034R1

Page 3 of 19

application. This can be accomplished by emailing the Records Room (RecordsRoom@cdc.gov) or

the Reviewer actively working the application. An approval request can be resubmitted after all 

guidance is considered and the requirements are met.

Note: It is not appropriate to refer to any product as NIOSH-approved, pending NIOSH approval, 

compliant to NIOSH standards, or similar claims prior to receiving the NIOSH approval. NIOSH 

approval encompasses NIOSH evaluation and acceptance of the respirator and the QMS. This 

cannot be achieved until the approval process is complete, including an engineering review, testing, 

and the assessment of the QMS by NIOSH. Similarly, if a product was once NIOSH-approved, but 

that approval was subsequently revoked or rescinded, the product may not be represented as 

NIOSH-approved.

Note: NIOSH expects the applicant to complete a full or limited production run (if all respirators are 

produced using the QMS presented to NIOSH) prior to submitting an application. The number of 

respirators produced prior to achieving NIOSH approval should be carefully considered because 

respirators not produced under the quality control system evaluated and accepted by NIOSH cannot 

be labeled as NIOSH-approved.

2 AUTHORITY

42 C.F.R. Part 84, Approval of Respiratory Protective Devices

3 TOPICS EXPLAINED

(i) Basic Application Procedure

a. PRIOR to SUBMITTING an APPLICATION toNIOSH

The applicant shall ensure all required documentation, performance requirements (testing), and 

quality assurance requirements are met.

A prospective applicant must first request a three-digit manufacturer’s code. This code is a tool used 

by NOSH to track application information and communications with applicants and approval 

holders. Applicants can request the code by emailing the Records Room (RecordsRoom@cdc.gov). 

Upon receiving the request for this code, information about the applicant, the first respirator 

configuration (all applicable parts and accessories) to be submitted for approval, and the applicant’s 

progress towards being able to submit an acceptable application will be collected. Once a code has 

been issued, NIOSH will provide the standard application form to initiate the application process. 

This code is for NIOSH tracking purposes; it in no way reflects NIOSH approval.

Every unique respirator submitted to NIOSH for approval requires the submittal of pre-submission 

test data to demonstrate that the respirator meets the NIOSH minimum performance 

requirements. These tests can be performed by the applicant or by a third-party laboratory. It is 

expected that the NIOSH Standard Testing Procedures (STPs) will be followed and appropriate test 

instrumentation must be used.
Document Number

NIOSH CA 2021-1034R1

Page 4 of 19

If applying for Surgical N95 respirator approval, there are additional pre-submission testing 

requirements including biocompatibility, flammability, and fluid resistance. A surgical N95, 

concurrently regulated by the Food and Drug Administration (FDA), is defined as a single-use,

disposable respiratory protective device (RPD) used in a healthcare setting that is worn by

healthcare personnel (HCP) during procedures to protect both the patient and HCP from the 

transfer of microorganisms, body fluids, and particulate material at an N95 filtration efficiency level 

per 42 CFR § 84.174. A surgical N95 respirator is a class II device, regulated by FDA under 21 CFR § 

878.4040 (FDA product code MSH). The guidance for submitting a Surgical N95 application to 

NIOSH can be found in CA 2018-1010R1.0 and must befollowed.

The NIOSH STPs list equipment and their specifications. If an applicant uses an alternate test 

method or equipment that has specifications other than those listed in the NIOSH STP, equivalency 

data showing correlation to the NIOSH method or specified equipment must be provided through 

a statistical study.

The following summarizes the documentation needed to meet the requirements of the related 

Standard Application Procedure (SAP). All documentation and respirators should be in their final 

form prior to submitting the application to NIOSH. Changes to documents submitted to a Reviewer 

actively working the application, without being requested, will not be accepted. If unrequested 

changes need to be made, the application should be withdrawn. NIOSH does not offer approval for 

prototype respirators.

a. Assembly Matrix (a matrix showing all possible hardware configurations to be 

evaluated in the application – must follow format in the SAP)

b. Draft Approval Label

c. Drawing(s)

d. Inspection Procedures

e. Product Quality Plans/Classification of Defects/Sampling Plans

f. Quality Manual – only required for new applicants and subsequent QAapplications

g. Pre-submission Test Data

h. Completed Standard Application Form

i. User Instructions

j. Test Samples

When an applicant submits an application, it is reviewed to ensure that all required sections of the 

application are included. Documents sent to NIOSH are expected to contain all required information 

and be compliant with all expectations in the SAP. If the application contains the required 

documents, application fee and test samples, NIOSH assigns a task number (TN). The TN is the 

internal tracking number for an application and should be used in all communication regarding the 

application. Once accepted, the project goes through multiple review stages including initial 

engineering review, QA review, testing, and final engineering review. For new applicants, prior to 

final review, NIOSH will conduct a site qualification assessment if all documentation and testing is

determined to meet the requirements during initial and QA review.

Note: NIOSH employees cannot review any documents that are not submitted as part of an 

application. Applicants should not submit any additional documents to NIOSH unless they are 

specifically requested by a Reviewer actively working the application. If changes that are not 
Document Number

NIOSH CA 2021-1034R1

Page 5 of 19

identified by a Reviewer are needed, the application should be withdrawn and resubmitted with 

information that is correct and meets the requirements in the SAP.

b. APPLYING for APPROVAL/APPLICATION ACCEPTED byNIOSH

Receiving a manufacturer’s code does not constitute an approval, registration, or acceptance of an 

application in any way; however, it is necessary to start the application process. Test samples 

provided with any application must be produced under the complete proposed QMS as presented 

in the application. NIOSH will verify this during the site qualification assessment. The minimum 

number of test samples required can be found by reviewing the information in the SAP relevant to 

the respiratory protective device that will be submitted for NIOSH approval. For a filtering 

facepiece, the applicant should provide a minimum of 26 samples. Additionally, it is expected that 

pre-submission test data also be reflective of products that were manufactured in accordance with 

the QMS system provided. NIOSH must receive all parts of the application package (i.e., documents, 

test samples, and $200 application fee) within two weeks of each other, or the application will be 

rejected. Each unique respirator design requires its own application. Respirators that are identical 

in all aspects except dimensions can be submitted in one application for one approval number (i.e., 

regular and smallsize).

(ii) NIOSH Quality Requirements:

NIOSH approval goes beyond assuring the device meets the appropriate minimum performance 

requirements defined by 42 CFR Part 84 for the intended protection. The approval extends to 

the entire QMS utilized to produce the respirators, which ensures that products produced

continue to meet the NIOSH performance requirements. NIOSH requires respirator approval 

holders to inspect and/or test samples of respirators and components as part of their quality

control plans. This requirement is stated in 42 CFR Part 84, specifically in § 84.41(b)-(i). Because 

of the stringent quality assurance requirements, this is often the part of the review process 

that applicants struggle with the most. The following sections reiterate the necessities of a 

comprehensiveQMS.

a. INSPECTION PROCEDURES and SAMPLINGPLANS

The regulation requires applicants to perform inspections before, during, and after production. All 

inspection procedures should be clearly defined in the quality documents and will be examined with 

scrutiny during the review process. Incoming inspection procedures should serve to verify that the 

materials received conform to the specifications that were ordered. In-process inspection 

procedures should verify the specifications and/or performance of all subcomponents of 

respirators. In-process inspection procedures are not required for single-assembly respirators (i.e., 

FFRs). Final inspection procedures should ensure that the fully assembled respirator conforms to 

the specifications on the drawing(s) and the required performance specifications. Specifications 

that are required to be called out on any drawings are expected to be verified as part of the 

inspections performed.

The overall goal of the quality control plan is to determine that the respirator produced conforms 
Document Number

NIOSH CA 2021-1034R1

Page 6 of 19

to the documentation submitted to NIOSH and the appropriate NIOSH performance requirements. 

The sampling plan being used for each inspection should be clearly stated and the documentation

should also include the definition of a lot or batch. If an applicant uses a performance testing 

procedure other than those commonly accepted by NIOSH, the equivalency must be explained.

The sampling plan procedures that are widely used and accepted as equivalent by NIOSH are listed 

in Table 1 below. For each sampling plan, there are acceptable minimum inspection levels for 

normal (defined in 42 CFR § 84.41(h)) and destructive inspections. The inspection level decides the 

number of samples to be drawn for a particular lot size and determines the sampling plan’s ability 

to discriminate between conforming and nonconforming lots. As a special exception, NIOSH is 

permitted under 42 CFR § 84.41(i) to allow a lower inspection level for destructive testing only. The 

minimum level NIOSH will accept under this exception is in the “destructive” column of Table 1 

below. Approval of a level lower than the “normal” level is entirely at NIOSH’s discretion and will 

only be granted if the rest of the inspection plan ensures adequate control over product quality. 

Historical data may be requested.

Stipulations for tightened inspection are required. If an applicant intends to use reduced 

sampling, those stipulations must be clearly outlined in the quality control plan and the applicant 

must demonstrate the ability to maintain control of the rules outlined in the sampling plan in use. 

For more details, see section below on “Use of SwitchingRules.”

Table 1. Widely used and accepted equivalent sampling plans along with the minimum inspection 

level accepted for each plan.

Procedure Minimum Inspection Level

Normal Destructive1

MIL-STD-414 IV I

ANSI/ASQ Z1.9-2003 II S-3

MIL-STD-105D II S-2

MIL-STD-105E II S-2

ANSI/ASQ Z1.4-2003 II S-2

ISO 28592 II S-2 1

Destructive inspections are considered those that, once performed, render the respirator or respirator component 

unable to be used.

2

Reduced sampling is not permitted with this plan.

Note: The Squeglia C=0 [Squeglia, 2008] procedure does not use the concept of inspection levels 

and NIOSH treats it as equivalent to inspection level II of MIL-STD-105D. If applicants or approval 

holders intend to use alternatives to the procedures described here, they must understand the 

concepts of acceptance sampling and process control. The use of more modern methods such as 

calculating process capability values (Cpk) or employing statistical process control can be accepted 

where this is compatible with the approval holder’s operations and provides equivalent assurance 

of respirator performance. Justification to demonstrate the equivalence of these procedures must 

be provided in the application seeking approval.
Document Number

NIOSH CA 2021-1034R1

Page 7 of 19

Cross-References. See MIL-STD-414 section A7.1; ANSI/ASQ Z1.9-2003 section A7.1; MIL-STD-105D 

sections 9.2, 9.3; MIL-STD-105E sections 4.9.1, 4.9.2; ANSI/ASQ Z1.4-2003 sections 9.2, 9.3;

Squeglia C=0 pages 3, 6.

b. CLASSIFICATION of DEFECTS

An important part ofthe quality control plan isthe classification of defects. Classifications of defects 

should be assigned correctly to all inspections according to the regulation (42 CFR § 84.41), as

detailed in Table 2. Respirators that consist of only one component (FFRs) are only required to have 

the classifications of defects assigned to incoming and final inspections. The classifications of 

defects are very specific to the Respirator Approval Program and the classification of defect 

definitions in sampling standards should not be used to define defects in NIOSH respirator quality 

plans. Each classification of defect has a corresponding acceptable quality limit (AQL) – as defined 

by the regulation (42 CFR § 84.41) – and all components of the respirator assembly should be 

appropriately sampled based on the AQL (Table 2).

Table 2. Classification of defect definitions from 42 CFR § 84.41 and the corresponding AQLs.

Classification of 

Defect

Definition Acceptable 

Quality Limit 

(AQL)1,2,3

Critical A defect that judgment and experience indicate is likely 

to result in a condition immediately hazardous to life or 

health for individuals using or depending upon the 

respirator

100%

Major A A defect, other than critical, that is likely to result in 

failure to the degree that the respirator does not 

provide any respiratory protection, or a defect that 

reduces protection and is not detectable by the user

1.0

Major B A defect, other than Major A or critical, that is likely to 

result in reduced respiratory protection, and is 

detectable by the user

2.5

Minor A defect that is not likely to materially reduce the 

usability of the respirator for its intended purpose, or a 

defect that is a departure from established standards 

and has little bearing on the effective use or operation 

of the respirator

4.0

1

These are called “index values” in the Squeglia (C=0) procedure.

2

It is acceptable to use a smaller (more stringent) AQL value.

3

Use of critical classification of defects should be considered according to the definitions in 42 CFR § 84.41(d). This 

classification is reserved for respirators used in immediately dangerous to life or health (IDLH) conditions.

Characteristics identified as Critical in the classification of defects are not assigned an AQL and 

are not eligible for any form of sampling. Each item made must be 100% inspected as required 

by 42 CFR § 84.41(f) and the entire lot rejected when a defect is found. NIOSH must approve 

any plans to perform rework on the lot as part of the product quality plan.
Document Number

NIOSH CA 2021-1034R1

Page 8 of 19

Note: Care should be taken to ensure that the sampling method, classifications of defects, and AQL 

are all applied correctly based on the inspection procedure(s) used. An example is provided as 

supplemental information.

Cross-References. See MIL-STD-414 section A4; ANSI/ASQ Z1.9-2003 sections A2.1, A4; MIL-STD105D section 4; MIL-STD-105E sections 3.1, 4.4; ANSI/ASQ Z1.4-2003 section 4; Squeglia C=0

pages 3, 6.

c. SELECTION of SAMPLING PROCEDURES

Sampling by Variables. The standard sampling procedure specified in 42 CFR Part 84 is MIL-STD414 [U.S. Department of Defense, 1957]. This is a variable sampling plan, which means that the 

characteristic must be something that can be measured numerically on a continuous scale. 

Examples include the diameter of a hole in inches, the mass of a cartridge in grams, or the leakage 

of an exhalation valve in milliliters per minute. This procedure is only valid when the characteristic 

being measured has a statistically normal distribution over the population being sampled. The 

ANSI/ASQ Z1.9 standard [American National Standards Institute 2003b] is derived from MIL-STD414, and NIOSH considers it to be equivalent.

Sampling by Attributes. The MIL-STD-105D sampling procedure [U.S. Department of Defense, 1963] 

is explicitly accepted as an equivalent procedure in 42 CFR Part 84. This is an attribute sampling 

plan, which means that each characteristic is simply checked to see whether it is acceptable. Due 

to its simplicity, this standard and its derivatives are the most common in use. It has the advantage 

that it can be applied to characteristics which do not involve a numerical measurement (such as 

visual checks) as well as to those that are measurable. No calculations are needed to determine 

acceptance, and the procedure is valid whether the characteristic has a normal distribution or not. 

Procedures derived from this standard, and which NIOSH considers to be equivalent, include MILSTD-105E [U.S. Department of Defense, 1989] and ANSI/ASQ Z1.4 [American National Standards 

Institute, 2003a].

Zero-Defect Sampling by Attributes. Another attribute sampling plan which NIOSH accepts as 

equivalent isthe Squeglia C=0 procedure [Squeglia, 2008]. While not directly derived from MIL-STD105E, its plans are matched to that procedure and provide an acceptable statistical assurance of 

lot quality. The chief difference is that in all cases, the lot is only accepted if there are zero defects 

found in the sample (C=0). This procedure usually requires fewer samples than MIL-STD-105D and 

related standards and is the simplest to use of those listed in Table 1. However, it is generally only 

suitable when defects in production are extremely rare.

Equivalent Standards. The ANSI/ASQ standards mentioned above are revised periodically. In 

general, NIOSH will consider later editions of a given procedure to be equivalent. There may also 

be other national or international standards based on MIL-STD-414 or MIL-STD-105D that can be
Document Number

NIOSH CA 2021-1034R1

Page 9 of 19

considered equivalent. If such a standard is used, NIOSH may request a copy from the applicant to 

verify its equivalence.

Use of Switching Rules. Tightened inspection is not optional and must be used where specified by 

the switching rules in the sampling plan being used. Most sampling plans referenced in this letter 

contain rules allowing reduced inspection under certain conditions. An applicant may use reduced 

inspection only when all conditions listed in the switching rules in the sampling plan being used are 

met. This includes the requirement that production is not irregular or delayed. A history of lot 

acceptance at one manufacturing site cannot be used to move to reduced sampling at anothersite. 

Approval holders may choose to stay at normal inspection even when conditions for reduced 

inspection are met. To use reduced inspection, the approval holder must maintain inspection 

records showing that the conditions in the applicable procedure are met. Such records must be 

available for review during NIOSH on-site audits. The Squeglia C=0 procedure does not recommend 

switching rules, and NIOSH does not permit reduced inspection for that procedure. Tightened 

inspection is not required for the Squeglia C=0procedure.

Note: One feature of MIL-STD plans is that, as works of the United States Government, they may 

be copied free of charge. Those mentioned can be downloaded from the Internet Archive at 

http://www.archive.org/ and may be available elsewhere. However, all MIL-STD documents in 

this letter have been cancelled by the Department of Defense and are no longer maintained or 

revised. The corresponding ANSI/ASQ standards are successors to the MIL-STD documents and 

have various minor improvements and clarifications added. Copies of these standards may be 

purchased from the American Society for Quality, the American National Standards Institute, or 

others who deal in national standards.

Cross-References. See MIL-STD-414 sections A8, B14, C14, D14; ANSI/ASQ Z1.9-2003 section A10; 

MIL-STD-105D section 8; MIL-STD-105E sections 4.6, 4.7, 4.8; ANSI/ASQ Z1.4-2003 section 8;

Squeglia C=0 pages 14, 16.

d. DEFINING LOTS or BATCHES

Definition of Lot. Each procedure listed in this letter requires that product be grouped into 

inspection lots (the term “batch” means the same as “lot”). Each lot consists of product which has 

been manufactured under essentially the same conditions, in the same production facility, and at 

essentially the same time. For example, if an applicant shuts down a production line for a week for 

maintenance, it is wrong to consider product made before and after the shutdown as part of the 

same lot. The applicant’s definition of a lot should be included in the application toNIOSH.

Selection of Samples from Lot. Each sample drawn from a lot must be representative of the entire 

lot. For example, when drawing a sample of 200 pieces from a lot of 10,000 it would be improper 

to select the first 200 respirators produced to use asthe sample. As another example, if respirators 

being produced on five machines are being combined into an inspection lot, then one-fifth of the 

sample drawn must come from each machine. As noted in section 3.ii.e of this letter, each sample 

taken for double or multiple sampling must be representative of the entire lot.
Document Number

NIOSH CA 2021-1034R1

Page 10 of 19

Inspection Lot vs. Other Lot Designations. The grouping of finished respirators into lots for 

shipment or other purposes may differ from the grouping used for inspection. The lot number 

marked on the respirator or its container, as required by 42 CFR § 84.33(g), does not necessarily 

need to be the same number used for inspection purposes. However, the approval holder must 

maintain traceability between lot numbering systems if more than one is used. For example, a 

shipping lot number must be traceable to the corresponding production lot number(s).

Cross-References. See MIL-STD-414 sections A5, A7.2; ANSI/ASQ Z1.9-2003 sections A2.4, A5, A7.2; 

MIL-STD-105D sections 5, 7.2; MIL-STD-105E sections 3.12, 3.13, 4.3, 4.5.1; ANSI/ASQ Z1.4-2003

sections 5, 7.2; Squeglia C=0 page 2.

e. SPECIFIC CONSIDERATIONS for ATTRIBUTE PLANS

Arrows on Sampling Tables. The Sampling Plan that is selected must be used correctly. This 

includes certain sampling plans that have tables containing arrows, which are to be followed to 

obtain the correct criteria (example below). Where the sampling plan indicated leads to an arrow

in the table, follow the arrow to the next available sampling plan. This will correspond to a new 

code letter row in the table with the acceptance and rejection numbers and a new corresponding 

sample size to be used.

As an example, consider sampling of a lot of 200 pieces under MIL-STD-105D for a Major A 

characteristic at inspection level II. Code letter G is selected from Table I, and an AQL of 1.0 is used. 

An arrow pointing downward is contained in Table II-A for these conditions, indicating that code 

letter G is not available and code letter H must be used. This means that the appropriate sample 

size is 50 pieces, not 32, and that the lot is accepted if there are zero or one defective pieces and 

rejected if there are 2 or more defectives.

Single, Double, or Multiple Sampling. Most attribute procedures include double or multiple 

sampling plans (the Squeglia C=0 procedure only has single plans). Any of these options included 

in the procedure may be selected. Note that each sample drawn must be representative of the 

entire lot. Double and multiple sampling tend to require fewer samples when lot quality is either 

much better or much worse than the AQL. Single sampling is simpler to administer and apply 

correctly than double or multiple sampling and should be carefully considered.

As an example, consider a lot of 200 pieces under MIL-STD-105D for a Minor characteristic at 

inspection level II. Code letter G is selected from Table I, and an AQL of 4.0 is used.

- For single sampling, Table II-A indicates that the sample size is 32. The lot is accepted if 

there are three or fewer defective pieces, and it is rejected if there are four or more 

defectives.

- For double sampling, Table III-A is used instead and an initial sample of 20 would be drawn. 

The lot is accepted if there are zero or one defectives, and it is rejected if there are four or 

more defectives. If there are two or three defectives, then a second sample of 20 is drawn 

from the lot and inspected. If after both samples (totaling 40 pieces) are inspected there 

are a total of four or fewer defectives, then the lot is accepted; if five or more defectives, 

then the lot is rejected.
Document Number

NIOSH CA 2021-1034R1

Page 11 of 19

- Multiple sampling (Table IV-A) works in a similar fashion, except that there are up to seven 

rounds of sampling to reach a decision.

Cross-References. See MIL-STD-105D sections 7.4, 9.5, 10.1.1, 10.1.2, 10.1.3; MIL-STD-105E

sections 4.5.3, 4.9.4, 4.10.1.1, 4.10.1.2, 4.10.1.3; ANSI/ASQ Z1.4-2003 sections 7.4, 9.5, 10.1.1,

10.1.2, 10.1.3.

f. SPECIFIC CONSIDERATIONS for VARIABLE PLANS

Variability Unknown vs. Variability Known. A variability unknown method should normally be used. 

The variability known method may only be used when the production processis understrict control 

and the process parameters influencing final respirator performance are well understood. Data 

must be provided with the application for approval, available during onsite audits, and 

continuously updated to support the standard deviation value (σ)used.

Single Specification Limit vs. Double Specification Limit. This is selected based on whether there is 

only one limit value (such as penetration less than or equal to 5%) or two limit values (such as 

cartridge mass between 95 and 105 grams) for the characteristic.

Standard Deviation Method vs. Range Method. Either method may be selected. The standard 

deviation method generally requires fewer samples, but more complex computations.

Cross-References. See MIL-STD-414 Introduction, section A6.2; ANSI/ASQ Z1.9-2003 Introduction, 

section A6.2.

g. COMMON ERRORS

Selection of Inadequate Inspection Levels. The minimum acceptable inspection level is described in 

section 3.2 of this letter. If a product quality control plan does not specify inspection levels, NIOSH 

assumesthat the level in the “normal” column of the table will be used. Use of lower levels without 

specific approval, whatever the reason, is a failure to conform to NIOSH requirements and can 

result in revocation of approval under 42 CFR § 84.43(c).

Selection of Plan Based on Desired Sample Size. It is entirely improper to choose a desired sample 

size and work backwardsto identify a proposed AQL and inspection level which will yield thisresult. 

To do so reflects a fundamental misunderstanding of the basis for sampling plans. The appropriate 

AQL and inspection level are stated in section 3.ii.b of this letter.

Selection of Defect Classification Based on Desired AQL. As in 9.2, the defect classification drives 

the selection of AQL, not the other way around. Each defect must be classified based solely on the 

definitions in 42 CFR §84.41(d).

Modification of AQL or Inspection Level Based on Lot Size or Other Factors. The AQL and inspection 

level are chosen by the criteria in section 3.ii of this letter. Approval holders are free to use higher 

inspection levels if greater discrimination is desired, or to use lower (more stringent) AQLs if a 

smaller percent defective is desired. However, these should not be modified based on lot size or
Document Number

NIOSH CA 2021-1034R1

Page 12 of 19

inspection history, as provisions already exist to account for those factors (i.e. switching rules). 

Changing AQL values or inspection levels is likely to result in a statistically invalid plan.

Inappropriate Use of Reduced Inspection. As described in section 3.ii.c of this letter, NIOSH permits 

reduced inspection only when all conditions of the relevant procedure are met. When there are 

significant delays or changes in production processes, approval holders must revert to normal 

inspection. It will be considered a nonconformance during NIOSH on-site audits if the records 

described in section 3.ii.i of this letter are not available.

Incorrectly Following or Not Following Arrows in Sampling Tables. When using attribute sampling, 

be careful when following applicable arrows in the sampling plan tables. A different sample size 

must be used to correspond with the new code letter as described in section 3.ii.e of this letter.

Improper Drawing of Samples. Each sample drawn must be representative of the entire lot as 

described in section 3.ii.d of thisletter. The typical method isto selectsamples at random. However, 

approval holders may use other methods (such as every tenth piece) so long as the sample is not 

biased in any way. If a lot contains multiple sublots, the sample must contain a proportional number 

of pieces from each sublot.

h. QUALITY MANUALS and QUALITY CONTROL PLAN

The requirements of a Quality Manual and quality control plan are outlined in the NIOSH

Conformity Assessment Notice 2019-1019, derived from 42 CFR Part 84. It is imperative that all 

elements are completely addressed. These elements must be fully implemented and utilized when 

samples are manufactured and sent to NIOSH for evaluation. Failure to do so will likely result in a 

failed site qualification assessment. Applicants must submit quality manuals for all manufacturing 

sites as well as all subcontractors (defined below).

i. FACILITY and PRODUCT AUDITS

Site Qualification Assessments: For new applicants, a site qualification visit is required for each 

manufacturing and subcontractor facility prior to gaining NIOSH approval. Depending on the 

application and manufacturing situation/locations, multiple site qualifications could be conducted 

before an approval can be issued. If multiple site qualifications are required, the scores of each site 

qualification are added together to determine the final score. Regardless of whether NIOSH 

assesses one site or multiple sites, a point system is used to score negative findings and the final 

additive score is what determines whether the applicant’s QA System is Acceptable, Provisionally 

Acceptable, or Not Acceptable.

For an existing approval holder who wishes to add a new manufacturing site or subcontractor, a 

Quality Assurance Application issubmitted, including the Quality Manual of any proposed new sites 

or subcontractors. A subcontractor agreement should be submitted for new subcontractors as 

described in section 3.iii.
Document Number

NIOSH CA 2021-1034R1

Page 13 of 19

The goal of the site qualification is to verify that the complete system that was presented to NIOSH 

is implemented and functional. NIOSH expects that the complete quality control system is in place 

before production of samples and submission of any applications. NIOSH performs the site 

qualification assessments based on the requirements in CA 2019-1019. Elements that are not 

typically assessed during the site qualification include: Contract Review Activities, Corrective 

Actions, Internal Audits, Training, and Quality Management. However, the auditors completing the 

assessment can verify these elements if they believe that there is evidence that these elements 

may cause the quality system to be inadequate. Auditors assigned to conduct these tasks will 

evaluate the system based on evidence that can be provided during the site qualification visit. If 

the evidence presented to the auditors does not support the process, it is unlikely that a site 

qualification assessment will be acceptable.

The auditors will assign any nonconformities or observations a score. The issues identified will be 

scored as a Major Finding (3 points), Minor Finding (1 point), or an Observation (0 points). At the 

end of the audit, or end of all audits if there are multiple sites, a final score will be determined.

• Zero points during site qualification assessment will result in an accepted QA System and 

the subsequent first NIOSHapproval.

• One to 11 points will result in a provisionally acceptable site qualification assessment, 

requiring corrective actions to be defined, implemented and accepted by NIOSH before the 

QA System is accepted and an approval can be issued.

• Twelve or more points will result in an unacceptable site qualification assessment and the 

application will be denied; before resubmitting the application, all identified issues must be 

fully addressed and documented in the re-submittedapplication.

Maintaining NIOSH Approval: After a manufacturing site has passed the initial site qualification and 

the applicant has received their approval, the applicant and any subcontractors will be added to 

NIOSH’s site audit schedule. NIOSH conducts these audits roughly once every two years to ensure 

that quality manufacturing practices are continually followed. Quality site audits verify 

conformance with the requirements of 42 CFR §§ 84.33, 84.40, 84.41, 84.42, and 84.43. All findings 

during the audit will be issued as corrective action requests that must be addressed for the NIOSH 

approval to remain valid. Additionally, annual product audits are performed to verify the 

performance and labeling of commercially availablerespirators.

Fees: For fees associated with all activities, please review the Respirator Certification Fee Schedules.

(iii) Supplier and SubcontractorRelationships

If a company wishes to seek approval but does not manufacture the respirators in-house, it is 

possible to still apply for NIOSH approval, but only if the company who is applying as the approval 

holder controls the quality and design of the product. In order to correctly present this information 

to NIOSH, the prospective approval holder should carefully review the definitions of a supplier and
Document Number

NIOSH CA 2021-1034R1

Page 14 of 19

a subcontractor (below). If subcontractors are used, the Quality Manual for the subcontractor 

should be supplied with the application, along with a subcontractor agreement that covers the 

elements required by the Subcontractor Relationship Responsibilities, outlined below. If multiple 

manufacturing sites are used for production or quality assurance, the Quality Manual for all 

applicable sites should be provided with the application.

Note: Roles and responsibilities within the QMS should not be confused with roles and 

responsibilities for NIOSH approved product private packaging and private labeling agreements. 

Please see NIOSH Conformity Assessment Notice 2020-1030 for information about private 

packaging and private labeling NIOSH approved respirators. It is expected that NIOSH-approved 

respirators are made following the QMS described to and accepted by NIOSH. 

Approval Holder. The party of record to whom certificates of approval will be or have been issued. 

The approval holder maintains responsibility for, and control of, product design, performance, 

configuration management, manufacture, quality, and support.

Supplier. A supplier produces components or subassemblies under their own quality system for 

delivery to the approval holder. The approval holder confirms the acceptability of incoming goods 

by accepting a Certificate of Compliance and inspecting incoming goods to ensure compliance with 

all product design, performance, and quality assurance criteria (drawings and engineering control). 

The approval holder releases the final product for distribution andsale. 

Subcontractor. The approval holder may authorize a subcontractor to release NIOSH-approved 

respirators directly from the subcontractor’s facility for distribution and sale, or to release 

components and subassemblies directly to an authorized repair center. This role and responsibility 

should be made clear in the documentation included in the application to NIOSH. The approval 

holder maintains responsibility for, and control of, product design, performance, configuration 

management, manufacture, quality, and support by maintaining influence over, and active 

involvement in, the subcontractor's quality system. As such, the subcontractor's facility is 

considered to be a manufacturing site for the approvalholder.

Subcontractor Relationship Responsibilities. The approval documentation on file at NIOSH must 

demonstrate that the following criteria have been met for NIOSH recognition of a subcontractor.

- As with all other NIOSH approvals, the approval holder maintains responsibility for all 

aspects of the approval: control over product design, performance, configuration 

management, manufacture, quality, and support. This includes product drawings, material 

specifications, parts lists, and manufacturing processes; control over the requirements for 

final inspection and testing; and approval of any changes to theabove.

- The approval holder must ensure that a subcontractor has demonstrated the ability to 

produce product that consistently meets the established release criteria and has adequate 

quality systems and procedures in place to assure product quality on an ongoing basis.

- The approval holder must establish and maintain active involvement and influence over 

subcontractor quality systems. This can be demonstrated in many ways. One example of 

this involvement and influence can be exhibited by participating in the subcontractor's 
Document Number

NIOSH CA 2021-1034R1

Page 15 of 19

management reviews (as defined by ISO 9001 sec. 5.6, 2000) required by the 

subcontractor's Quality System. A second example is participation in the subcontractor's 

Material Review Board.

- The approval holder's methods for maintaining active involvement and influence over their 

subcontractor's quality system needs to be documented in a plan or procedure that suits 

the individual situation and manufacturing complexity of the secured goods. The approval 

holder must formally submit this plan or procedure toNIOSH.

- The approval holder will maintain copies of subcontractor quality records that demonstrate 

compliance with NIOSH performance requirements. It is important to ensure that, in the 

event of a broken relationship, both the approval holder and NIOSH have continued access 

to those records.

- All submissions related to the approval must be made by an authorized representative of 

the approval holder. The subcontractor's Quality Manual and related quality system 

documents must represent how the approval holder establishes and maintains active 

involvement and influence over the subcontractor's quality system. This information must 

be specifically indicated and documented as part of a Quality Assurance application if the 

subcontractor is added after an initial approval application.

- As with all Quality Manuals, a process must be established and followed for ongoing 

resubmission of the Quality Manual and related quality system documents in the event of 

significant changes, and on a periodic basis, per NIOSHrequirements.

- All subcontractor relationships must be listed as an approval holder's manufacturing site, 

with a designated point of contact, on the NIOSH Standard Application Form (SAF) for direct 

shipment from the subcontractor to be acceptable under the NIOSHapproval.

- NIOSH will audit all manufacturing sites for NIOSH-approved products, including 

subcontractor facilities, every two years. NIOSH will not contact the subcontractor directly 

but will always work through the approval holder's designated representative for the 

specific manufacturing site.

4 SUPPLEMENTAL INFORMATION – EXAMPLEONLY

The following table is provided merely as an example. The numbers and plans in Table 3 are not 

a representation of a quality plan used for a currently approved respirator but were included to 

show that a combination of various sampling plans may be utilized. Information and values, 

presented as “#” below, are for illustrative purposes only.

Table 3. Example of how the sampling method, classifications of defects, and acceptable quality 

limits could be presented to NIOSH (provided for illustrative purposes only).
Document Number

NIOSH CA 2021-1034R1

Page 16 of 19

Inspection Procedure Classification 

of Defect

AQL Sampling 

Standard

Sampling 

Level

Inspection 

Description

Inspection 

Method/ 

Equipment

Inspection 

Criteria

Incoming IN1 Major A 1.0 C=0 Filter Media 

basis 

weight

Balance ## gsm*

+/-## gsm

IN2 Major A 1.0 MIL-STD105DS-2 Filter Media 

filtration 

efficiency

TSI 8130 Particle 

filtration

≥ 95%

IN3 Major A 1.0 MIL-STD105DS-2 Strap 

elasticity

Tensile 

tester

###%, # N

IN4 Minor 4.0 MIL-STD105DGeneral 

Level II

Media 

Appearance

Visual No stains, 

defects 

visible

IN5 Major A 1.0 C=0 Outer layer 

basis 

weight

Balance ## gsm

+/-## gsm

IN6 Major A 1.0 C=0 Inner layer 

basis 

weight

Balance ## gsm

+/-## gsm

In-Process IP1 Major B 2.5 MIL-STD105DGeneral 

Level II

Head strap 

length 

verification

Steel ruler ### ± #

mm

IP2 Major B 2.5 MIL-STD105D

General 

Level II

Dimension 

verification

Caliper Length

### ± ##

mm 

Width

### ± ##

mm

IP3 Major A 1.0 MIL-STD105D

General 

Level II

Strap 

attachment 

strength

Weight Breakage 

point

Final FI1 Major A 1.0 MIL-STD105DS-2 Filtration 

efficiency

TSI 8130 Particle 

filtration

≥ 95%

FI2 Major A 1.0 MIL-STD105DS-2 Inhalation 

resistance

Manometer ≤ 35

mmH20

FI3 Major A 1.0 MIL-STD105DS-2 Exhalation 

resistance

Manometer ≤ 25

mmH20

FI4 Major A 1.0 MIL-STD105DS-2 Exhalation 

valve 

leakage

Gilibrator ≥ 30

mL/min

FI5 Minor 4.0 MIL-STD105D

General 

Level II

Appearance Visual No stains, 

printing 

legible, no 

frayed 

edges

*gsm is defined as grams per square meter
Document Number

NIOSH CA 2021-1034R1

Page 17 of 19

5 CONTACTING THE RESPIRATOR APPROVAL PROGRAM

If you have any questions regarding the information provided in this document or elsewhere, 

please feel free to reach out to the Respirator Approval Program. You will be put in contact with 

the appropriate party to answer your question(s). Respirator Approval Program employees cannot 

act as consultants, but they will be able to answer specific questions about the approval process 

and requirements.

All emails to the Respirator Approval Program should include your company name in the 

subject line. If you have a 3-letter manufacturer’s code, this should also be included.
Document Number

NIOSH CA 2021-1034R1

Page 18 of 19

6 REFERENCES

Approval of Respiratory Protective Devices, 42 CFR Part 84

Standard Application Procedure for the Approval of Air-Purifying Filtering Facepiece Respirators

Under 42 CFR Part 84, revised March 12, 2018, Sections 3.1 and 3.2

Standard Application Procedure for the Approval of Closed-Circuit Escape Respirators Under 42 CFR

Part 84, revised October 16, 2018, Sections 3.1 and 3.2

Standard Application Procedure for the Approval of Supplied-Air Respirators, Industrial SelfContained Breathing Apparatus, and Combination Supplied-Air Respirators/Industrial SelfContained Breathing Apparatus Under 42 CFR Part 84, revised March 12, 2018, Sections 3.1 and 

3.2

Standard Application Procedure for the Approval of Powered Air-Purifying Respirators and

Chemical, Biological, Radiological and Nuclear Powered Air-Purifying Respirators Under 42 CFR Part

84, revised March 12, 2018, Sections 3.1 and 3.2

Standard Application Procedure for the Approval of Air-Purifying Respirators and Chemical,

Biological, Radiological and Nuclear Air-Purifying Respirators Under 42 CFR Part 84, revised March

12, 2018, Sections 3.1 and 3.2

Standard Application Procedure for the Approval of Self-Contained Breathing Apparatus, and

Chemical, Biological, Radiological and Nuclear Self-Contained Breathing Apparatus Under 42 CFR

Part 84, revised March 12, 2018, Sections 3.1 and 3.2

NIOSH Conformity Assessment Notice (CA 2019-1012) | NPPTL | NIOSH | CDC

NIOSH CA 2019-1019 – NIOSH Quality Control Plan Requirements

NIOSH CA 2020-1030 – Requirements and Responsibilities of Approval Holders and Assignees in 

NIOSH Approved Respirator Private Labeling and Private Packaging Arrangements

American National Standards Institute [2003a]. Sampling procedures and tables for inspection by 

attributes. Milwaukee, WI: American Society for Quality, American National Standard ANSI/ASQ 

Z1.4-2003.

American National Standards Institute [2003b]. Sampling procedures and tables for inspection by 

variables for percent nonconforming. Milwaukee, WI: American Society for Quality, American 

National Standard ANSI/ASQ Z1.9-2003.

Squeglia NL [2008]. Zero acceptance number sampling plans. 5th ed. Milwaukee, WI: American 

Society for Quality.

U.S. Department of Defense [1957]. Sampling procedures and tables for inspection by variables for 

percent defective. Washington, DC: Office of the Assistant Secretary of Defense (Supply and 

Logistics), Military Standard MIL-STD-414 (including Notice 1, 8 May 1968).
Document Number

NIOSH CA 2021-1034R1

Page 19 of 19

U.S. Department of Defense [1963]. Sampling procedures and tables for inspection by attributes. 

Washington, DC: U.S. Government Printing Office, Military Standard

MIL-STD-105D (including Change Notice 2, 20 March 1964).

U.S. Department of Defense [1989]. Sampling procedures and tables for inspection by attributes. 

Washington, DC: Department of Defense, Military Standard MIL-STD-105E.

International Organization for Standardization [2000]. Quality management systems — Requirements

(ISO Standard No. 9001). Retrieved from https://www.iso.org/standard/21823.html.

Revision (R) Date Reason for Revision

1.0 12 May 2021 NIOSH revised this notice based on HHS review and comments.