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Revised “Cautions & Limitations” List for CBRN Air-Purifying Respirators (APR)

Letter to All Respirator Manufacturers

Issue Date: June 15, 2006

From: Heinz W. Ahlers, Acting Chief, Technology Evaluation Branch, National Personal Protective Technology Laboratory

Subject: Revised “Cautions & Limitations” List for CBRN Air-Purifying Respirators (APR)

This letter is being issued to revise the “Cautions and Limitations for Use” dated March 14, 2003 as found in the CBRN APR Standard dated April 4, 2003. The March 14, 2003 list of “Cautions & Limitations for Use” did not include the necessary code letters that are to be used.

The following are the Cautions & Limitations that must be used on the CBRN APR respirator and canister approval labels and must be included in the User Instructions:

A — Not for use in atmospheres containing less than 19.5 percent oxygen.

J — Failure to properly use and maintain this product could result in injury or death.

L — Follow the manufacturer’s User Instructions for changing cartridges, canisters and/or filters.

M — All approved respirators shall be selected, fitted, used, and maintained in accordance with MSHA, OSHA, and other applicable regulations.

O — Refer to User’s Instructions and/or maintenance manuals for information on use and maintenance of these respirators.

R — Some CBRN agents may not present immediate effects from exposure, but can result in delayed impairment, illness, or death.

S — Special or critical User Instructions and/or specific use limitations apply. Refer to User Instructions before donning.

T — Direct contact with CBRN agents requires proper handling of the respirator after each use and between multiple entries during the same use. Decontamination and disposal procedures must be followed. If contaminated with liquid chemical warfare agents, dispose of the respirator after decontamination.

V — Not for use in atmospheres immediately dangerous to life or health or where hazards have not been fully characterized.

W — Use replacement parts in the configuration as specified by the applicable regulations and guidance.

X — Consult manufacturer’s User Instructions for information on the use, storage, and maintenance of these respirators at various temperatures.

Y — The respirator provides respiratory protection against inhalation of radiological and nuclear dust particles. Procedures for monitoring radiation exposure and full radiation protection must be followed.

Z — If, during use, an unexpected hazard is encountered such as a secondary CBRN device, pockets of entrapped hazard or any unforeseen hazard, immediately leave the area for clean air.

CC — For entry, do not exceed maximum use concentrations established by regulatory standards.

HH — When used at defined occupational exposure limits, the rated service time cannot be exceeded. Follow established canister change-out schedules or observe End-of-Service-Life Indicators to ensure that canisters are replaced before breakthrough occurs.

QQ — Use in conjunction with personal protective ensembles that provide appropriate levels of protection against dermal hazard. Failure to do so may result in personal injury even when the respirator is properly fitted, used, and maintained.

UU — The respirator should not be used beyond eight (8) hours after initial exposure to chemical warfare agents to avoid possibility of agent permeation. If liquid exposure is encountered, the respirator should not be used for more than two (2)hours.

If the respirator contains electronic components, add:

I — Contains electrical parts that may cause an ignition in flammable or explosive atmospheres.

If you need additional information, please contact NIOSH at 412-386-4000 or e-mail at

Revised Cautions and Limitations List for CBRN Air-Purifying Respirators (APR) [PDF – 33 KB]