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○ Standard Interpretations - Table of Contents

• Standard Number: 1910.134(g); 1910.120; 1910.156

OSHA requirements are set by statute, stan dards and regulations. Our interpretation letters explain these requirements and how th ey apply to particular circumstances, but they cannot create addition al employer obligations. Thisletter constitutes OSHA's interpretation of the requirements discussed. Note that our enforcement guidance may be affected by changes to OSHA rules. Also, from time to time we update our guidance in response to new information. To keep appr ised of such developments, you can consult OSHA's website at http://www.osha.gov.

May 1, 1995 MEMORANDUM FOR: REGIONAL ADMINISTRATORS FROM: JAMES W. STANLEY, DEPUTY ASSISTANT SECRETARY SUBJECT: Response to IDLH or Potential IDLH Atmospheres
The agency has recently received a number of requests for interp retation of the Occupational Safe ty and Health Administration ( OSHA) requirements for workers who are actively conducting operatio ns in atmospheres that are immediately da ngerous to life and he alth (IDLH). The spe cific question posed is whether OSHA regulations mandate the minimum number of workers requir ed to be involved in operatio ns under IDLH or potential ID LH conditions. The purpose of this memorandum is to clar ify requirements under all of the applicable standards which have a bearing on this qu estion, namely: Hazardous Waste Operations and Emergency Response (HAZWOPER), 29 CFR 1910.120; Respiratory Protection, 29 CFR 1910.134; Fire Brigades, 29 CFR 1910.156; and Section 5(a)(1) of the Occu pational Safety and Health Act of 1970. It is inte nded to apply to operatio ns where IDLH conditions exist or potentially exist in the following situations:

1. Emergency responses to uncontrolled releasesof a hazardous substance or substances; 2. Emergency operations covering interior structural fire fighting. As will be explained in greater detail later in the memorandum, th e interpretations given herein are not intended to apply to p ersonnel prior to initiation of IDLH operations. At the end of the memorandum is a two page summary to which persons who do not have a n eed to follow in detail the reasons which led the Agency to the particular requirem ents contained therein may refer. This memorandum does not address entry into a confined space containing an IDLH atmosphere. That subject is addressed in the Pe rmit Required Confined Space standard, 29 CFR 1910.146, and is discussed in the compliance directive on that standard. CLARIFICATION OF 1910.120: Attached for your reference is a copy of an August 15, 1994, letter to Ms. Peg Semina rio of the AFL-CIO that provides OSHA's cu rrent interpretation of the HAZWOPER standard as it relates to IDLH operations. The letter specifically addres ses the HAZWOPER requirement for workers who are engaged in remedial operations as well as in emergency responseoperations in atmospheres which are or ma y be IDLH and who ut ilize self-contained b reathing apparatus (SCBA) for the control of inhalation hazard(s). The HAZWOPER standard addresses three categories of employees: workers at hazardous waste sites (paragraphs b-o), workers at Tr eatment, Storage, and Disposal facilities (paragraph p) and workers in workplace situatio ns where they face an actual or potential emergency from therelease of hazardous substances (paragraph q). Fire fi ghters are often involved in emergency response operations when serving as members of an organ ized HAZMAT team, and as such, would be covered bythe HAZWOPER standard. Was this page helpful? 

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8 /4 /201 5 https://www.osha.gov/pls/oshaweb/owadisp.s how_document?p_table=IN TERPRETATIONS&p_id=21788Paragraph 1910.120(q)(3)(v) of HAZWOPER requires that "operations in hazardous areas (emphasis added) shall be perfor med using the buddy system in groups of two or more." In addition, paragraph 1910.120(q)(3)(vi) states that "back up personnel shall stand by with equipment ready to provide assistance or rescue." This section means that as a minimum the buddy system must be used within the hazardous area (entry by at least two pe rsons) and at least two additional personnel shall stand by outside the hazardous area. Th us, there must be at least four individuals at the site. One of the two individuals outside the hazard area can be assigned to another task, provided that the second assignment does not interf ere with the performance of thestandby role. Regarding the use of buddy system s, OSHA understands the HAZWOPER standard to me an the following: a buddy shall be assigned whois able to: (1) provide the partner with assistance; (2) observe the partner for signs of chemical, heat, or other hazardous exposure; (3) periodically check the integrity of the partner's personal protective equipment/clothing; and (4) if emer gency help is needed, notify th e appropriate individual (i.e., the Command Post Supervisor, the On-Scene Incident Commander). The standard defines a "buddy system" and "IDLH" below as:

Buddy system means a system of organizing em ployees into workgroups in su ch a manner that each employee of the work group is de signated to be observed by at least one other employee in the work group. The pu rpose of the buddy system is to provide rapid assistance to em ployees in the event of an emergency. IDLH or Immediately dangerous to life or health means an atmosp heric concentration of any toxic, corrosive or asphyxiant substa nce that poses an immediate threat to life or would cause irreversible or delayed adverse health effects or would inte rfere with an individual's ability to escape from a dangerous atmosphere. Please refer to OSHA Instruction CPL 2-2.59, "Inspection Procedures for the Hazardous Waste Operations and Emergency Response S tandard, 29 CFR 1910.120, paragraph (q): Emergency Response to Hazardous Substance Releases," for furt her compliance guidanceand information o n paragraph (q). CLARIFICATION OF 1910.134: The Respiratory Protection standard, 29 CFR 1910.134, which does apply to operations covered by OSHA's Fire Brigade Standard wi ll be discussed next. Paragraph (e)(3), requires the development of written procedures for the safe use of re spirators in IDLH an d potential IDLH atm ospheres. Paragraphs (e)(3)(i) and (ii) of the standard specifically state that: (3) Written procedures shall be prepared covering safe use of respirators in da ngerous atmospheres that might be encountered in normal operations or in emergencies. Personnel shall be familiar with these procedures and the available respirators. (i) In areas where the wearer, with failure of the respirator, co uld be overcome by a toxic or oxygen-deficient atmosphere, at least one additional man shall be present. Communications (visual, voice, or signal line) shall be maintained between both or all individuals present. Planning s hall be such that one individual will be unaffected by any likely incident and have the proper rescue eq uipment to be able to assist the other(s) in case of emergency. (ii) When self-contained breathing apparatu s or hose masks with blowers are used in atmospheres immediately dangerous to life o r health, standby men must be present with suitable rescue equipmen t." (Please note that NIOSH no longer approves hose masks with blowers for IDLH). Paragraph (i) addresses workplace conditions where an IDLH atmosphere is possible but not presently existin g. It requires at le ast one standby person to be present in communication with the worker(s) who are in the area of the potential IDLH. This standby person must be located outs ide of the potential IDLH exposure area and, therefore, would be able to prov ide or call for emergency assistance, if necessary. Paragraph (ii) requires that for known or existing IDLE atmospheres, at least two standby persons must be present with positive pressure self-contained breathing apparatus (SCBA) and retrieval equipment for emergency assistance. Consequently, the Respiratory Protection stan dard requires a minimum of two personnel tofunction in a standby capacity and loc ated in a safe area to monitor and provide emergency assistance to worker(s ) in a known IDLH atmosphere . This rule does not addre ss the number of workers requ ired within the IDLH hazardous area, nor does it explicitly requ ire the use of a "buddy system" as defined in the HAZWOPER standard. However, a "bud dy system" approach would be in compliance with 1910.134. According to 1910.134, written proc edures must be developed to ad dress the safe use of respirator s in dangerous atmospheres tha t may be encountered either in normal operations or in emer gencies. These procedures must include a plan fo r rescue based on any circumstances that can rea sonably be anticipated during the operation. In the event that rescue of worker(s) from the ha zardous area is necessary, the standard requires a minimum of two properly trained and equipped individuals to remain outside of the hazard area, one una ffected by the incident who is to maintain communications wit h all parties, to coordinate the rescue and summon additional assistance, if necessary. The other must be trained, equipped and available to effect a successful rescue. If appropriate, an employer may elect to use non-entry rescue, such as retrieval systems using safety ha rnesses and safety lines, for removing persons from hazardous atmospheres. The Respiratory Protection standard is curr ently being amended. The proposed rule was published in the Federal Register (59 FR 219) on November 15, 1994. The written comment period was extended to April 13, 1995. This document was edited on 04/01/99 to strike inform ation that no longer reflects current OSHA policy.] CLARIFICATION OF 1910.156: The Fire Brigade standard, 29 CFR 1910.156, contains mandatory requ irements for fire fighting unit s. The standard covers only e mergency operat ions involving interior structural fire fighting. Because fire brigades vary in type, function and size, the OSHA requirements are performance oriented to provide enough flexibility for the employer to organi ze a fire brigade which best refl ects the needs of the workplace. 

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8 /4 /201 5 https://www.osha.gov/pls/oshaweb/owadisp.s how_document?p_table=IN TERPRETATIONS&p_id=21788In 29 CFR 1910.155, "Scope, applicat ion and definitions applicable to this subpart" (i.e., Subpart L) defines interior structural fire fighting as: "the physical activity of fire suppression rescue or both inside of buildings or enclosed structureswhich are involved in a fire situation b eyond the incipient stage." Enclosed structure means: "a structure wi th a roof or ceiling and at least two walls whic h may present fire hazards to employees, such a s accumulations of smoke, toxic gases and heat, similar to those found in bu ildings." An incipient stage fire is define d by the regulation as: "a fire which isin the initial or beginning stage and which can be controlled or extinguished by portable fire exting uishers, Class II standpipe or small hose systems without the ne ed for protective clothing or breathing apparatus. It is universally recognized that conditions present during an advanced Interi or structural fire create an IDLH. The Fire Briga de standard does not directly address the minimum number of fire fighters required when engage d in operations presenting an IDLH atmosphere. Regarding the us e or SCBA's in IDLH atmospheres, paragraph 1910.156(f)(1)(i) doesrefer to the Respiratory protection standard, 1910.134, which has been discussed earlier. APPLICATION OF RELEVANT NFPA STANDARDS Two national consensus standards are relevant to the issue of fi re fighter safety and provide further detailed requirements forthe industry. The first standard is NFPA 1500-1992, entitled Fire Department Occupational Safety and Health Program. It has an interim amendment (attached) that states at 6-4.1.1: "At least four members shall be assemb led before initiating interior fire fighting op erations at a working structural fire." Workin g structural fire is defined in section 1-5 as follows: Any fire that requires the use of a 1 and 1/2 inch or larger fire atta ck hose line and that also requires tee u se of self-contained breathing apparatus for members entering the hazardous area." in reality th e term means the same thing as the OSHA term interior structur al fire fighting. Consequently, four persons, two in and two out, each wi th protective clothing and respiratory protection are essential fo r the safety of thos e performing this work inside a structure. In addition to this interim amendment, NF PA 1500 has other relevant criteria found in requirements 6-4.3 and 6-4.4. In 6-4.3 th e standard requires members operating inside hazardous areas during emergency incidents to operate in teams of two or more. Team members operating within h azardous areas shall be in communication with each other through visual, audible, physical, safety guiderope, electronic means or other means to coordinate their activities. Section 6-4.4 further requires that in the initial stages of an incident, where only one team is operating in the hazardous are a, at least one additional member shall be assigned to stand by outside the hazardous area where the team is operating. This stan dby member shall be responsible for maintaining constant awareness of those working in the hazardous area, their location, time of entry, functions, and iden tity. A second person (the incident commander) outside the hazard area is specified by Section 6-1 of the NFPA 1500. In summary, NFPA 1500, requires fo ur fire fighters on th e scene before performing interior st ructural fire fighting operations, and, when fire fighters or other personnel actually perfor m interior attack, they are to enter the hazardous area using te ams of at least two members. The second applicable NFPA standard is NFPA 600-1992, Standard on Industrial Fire Brigades (attached) Chapter 5 of this stan dard entitled, "Fire Brigades That Perform Interior Structural Fire Fighti ng Only," paragraph 5-3.5, specifies requirements for the number of members to be i nvolved at the scene. Requirements in 5-3.5 are almost exactly the same as those in Sections 6-4. 3 and 6-4.4 of NFPA 1500. Additionally, NFPA 600 and NFPA 1500 both require a fire officer tobe the incident manager. This NFPA requirement, along with the other requirements discussed above, results in a minimum of four members on the scen e before beginning to fight inte rior structural fires: two ins ide as a team, operating in the hazardous area; two outside the hazardous area, where one is standing by and another may be performing another function, such a s managing the incident, as long as its performance does not interfere with the second outside pers on's ability to assist in th e event of an emergency. This standard does not address the number of persons necessary to staff a fire apparatus leaving a station before on-s cene evaluation has occurred. That is a matter to be determined by each local fire fighting unit. APPLICATION OF THE GENERAL DUTY CLAUSE Occupational exposure to fire is a well-re cognized serious hazard and feasible abatement methods ex ist. Therefore, application of Section 5(a)(1) may be warranted in some circumstances. Any citation or Sectio n 5(a)(1) must meet the requirements outlined in the Field Inspection Reference Manual ( FIRM ), Chapter III, and may be issued where there is a hazard which cannot be abated by compliance with a specific OSHA standard. Because OSHA's Fire Brigade standard does no t directly specify the number of fire figh ters who can safely perform certain fire fighting operations, the NFPA national consensus standards serve as guidance as to what is ge nerally recognized as hazardous in the industry. The two NFPA standards referred to above explicitly address the number of persons to be involved when performing interior structural fire fighting operations. The requi rements contained in these NFPA standards do not apply to exterior fire fi ghting or to other fire fighting activiti es not involving IDLH conditions. Therefore, a citation for violation of the General Duty Clause shall be issued when it is do cumented that only one person conducted interior structural fire fighting operations o r when less than two persons were standing by when interior structural fire fighting operat ions were being conducted. A Section 5(a)(1) citation may not be issued for incipient stage interior fires or for exterior fire fighting operations conducted during adva nced interior structural fires. STATE PLANS Regional Administrators shall explain the co ntent of this memorandum to the State desi gnees as requested. States are strongly e ncouraged to adopt an identical or at least as effective interpre tation of the standards. As indicated in STP 2-2.8B, Fire Protection, because of theunique nature of fire fighting employment in the public sector, a State ma y develop alternate standards for State and local government employees as long as th e program provides protection equivalent to that provided pr ivate sector employees. If the State develops a separate public sector standard, it mu st be submitted within 30 days of promulgation in accord ance with STP 2-1.117. Federal OSHA does not have direct jurisdiction over State and lo cal government employees. Howeve r, the Occupational Safety and Health Act allows States to administer their own occupational safety and health prog rams under plans approved and monito red by Federal OSHA. States with ap proved occupational safety 

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8 /4 /201 5 https://www.osha.gov/pls/oshaweb/owadisp.s how_document?p_table=IN TERPRETATIONS&p_id=21788Freedom of Information Act | Privacy & Secu rity Statement | Disclaimers | Import ant Web Site Notices | International | Contact Us U.S. Department of Labor | Occupational Safety & He alth Administration | 200 Consti tution Ave., NW, Washington, DC 20210 Telephone: 800-321-OSHA (6742) | TTY www.OSHA.gov and health State plans must adopt standard s which are at least as effective as Fede ral OSHA standards and must provide coveragefor State and local government employees as effective as that provided to private se ctor employees. (In states withou t OSHA approved plans, the Fed eral workplace protection provided to public sector employees would be under the Environmental Pr otection Agency hazardous wa ste operations (HAZWOPER) re gulation (40 CFR Part 311); States may also enforce their own laws and regulations covering the public sector. This guidance supersedes any previously provided on the issue. Should you have any questions or comments, please contact Tom Ga lassi at (202) 219-8036. Attachments

SUMMARY REQUIREMENTS FOR RESPONSE TO IDLH OR POTENTIAL IDLH ATMOSPHERES USING SELF-CONTAINED BREATHING APPARATUS

◾ The HAZWOPER standard requires the use of th e buddy system with standby personnel for emergency response op erations involving t he release of hazardous substance(s) producing IDLH conditions for employees responding. The regulati on specifies a minimum of four personnel, two as a team in the buddy system and two standby back-up personnel, to conduct operations in hazardous areas safely.

◾ The use of SCBAs in IDLH atmospheres for circumstances not covere d by HAZWOPER is cove red by the Respiratory Protection standar d which requires two

standby personnel to be present outs ide the IDLH hazard area. Failure to have two standby persons for a known, existing IDLH , e.g., an interior structural fire, would be a violation of 1910.134(e)(3)(ii). [This document was edited on 04/01/99 to strike info rmation that no longer refl ects current OSHA policy.]

◾ The Fire Brigade standard covers employers whose employees perform interior attack on interior structural fires and references the Respiratory Protection

standard's requirements above.

◾ The National Fire Protection Association (NFPA) recognizes that fire fighters must oper ate in teams of two or more when conduct ing interior structural fire

fighting operations; failure to respond with teams of two or more would be a violation of the General Duty clause.

◾ The Respiratory Protection standard and industry practice (as co dified through the NFPA standard s) require that a minimum of fo ur fire fighters be involved in emergency operations during interior structural fire fighting . Two act as a team in the hazard area, and two stand by outsid e the hazardous area to monitor the operation and provide assistance should a rescue be necessary.

◾ OSHA regulations and NFPA standards specifically require communica tion between members of the team . Fire fighters working in te ams of two or more

(buddy system) in hazardous areas (IDLH atmo spheres) are required to main tain communications (voice, visual contact, or tetheri ng with a signal line). Radios or other means of electronic contact shall not be substi tuted for direct visual contact between employees within the ind ividual team in the danger area.

◾ One of the individuals outside of the hazard area may be assigned more than one role, such as the incident commander in charge of the emergency or

operator or fire apparatus, where it doesnot jeopardize worker safety and health.

◾ Incipient fires, which do not create IDLH at mospheres or require the use of SCBA's or fire fighting activities conducted from o utside a structure are not

addressed by this stan dard interpretation. [Corrected 11/30/2006]

○ Standard Interpretations - Table of Contents 

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