|When the subject of air monitoring is brought up, it is almost always in the context of hazardous materials response. Rarely do hazardous materials responders discuss air monitoring as an integral (and required) facet of the technical rescue disciplines of confined space entry; and trench rescue and recovery. To ensure the safety of personnel, effective scene operations, and compliance with applicable regulations it is imperative that technical rescue personnel have training in and develop a thorough knowledge of air monitoring techniques.|
Optimally, hazmat team personnel should be trained in the air monitoring requirements relating to technical rescue operations so that they can provide valuable assistance at confined space and trench rescue/recovery incidents in settings that are already of a personnel-intensive nature.
The Occupational Safety and Health Administration (OSHA) stipulates the requirement for air monitoring in permit-required confined space entries in 29 CFR 1910.146, which is the OSHA Standard relating to permit-required confined spaces. OSHA defines a confined space as “a space in which employees can bodily enter and perform work; has limited or restricted means of entry or exit, and is not designed for continuous employee occupancy.” Permit-required spaces are a subset of confined spaces that contain a hazard or possible hazard. As such, permit-required confined spaces represent an environment that is highly dangerous for those entering to perform work and for those performing rescues of personnel in such locations.
OSHA Standard 29 CFR 1910.146(d)(5) requires that all permit-required confined spaces be tested prior to entry to determine if acceptable entry conditions exist. In locations such as sewers that form a continuous system, pre-entry monitoring shall be performed to the greatest extent possible prior to entry and then shall be performed continuously in the areas in which personnel are present. Interestingly enough, the Standard states that in situations in which the atmosphere can be tested prior to entry, monitoring shall be performed “as necessary” during all entry operations. That statement highlights the need for trained, competent air monitoring personnel to determine what “as necessary” is defined as.
OSHA also requires that the atmosphere in permit-required confined spaces be tested for oxygen concentration first, then flammability, then toxicity. Any authorized entrants or their representatives are also provided the opportunity to observe air monitoring operations; and have the ability to request re-evaluation of the space and access to the results of the air monitoring.
Air monitoring is also an integral portion of entering permit-required confined spaces under the “alternative procedures” stipulated in 29 CFR 1910.146(c)(5)(ii). These procedures allow for entry into permit-required confined spaces in which the only hazard is an actual or potentially hazardous atmosphere in which continuous forced air ventilation renders the atmosphere safe.
In such situations, the Standard requires that the atmosphere shall be monitored prior to entry with a “calibrated, direct-reading instrument” for oxygen concentration, flammability and toxicity. The atmosphere shall also be “periodically” tested to ensure the safety of the atmosphere and the efficacy of the ventilation. A permit-required confined space may also be reclassified as a non-permit required space per 29 CFR 1910.146(c)(7) if it can be shown that no actual or potential atmospheric hazards exist and that all other hazards can be eliminated without entering the space. As can be surmised, air monitoring is an integral part of this process.
One may then ask what our levels of concern are for our air monitoring activities in permit-required confined spaces. OSHA defines a “hazardous atmosphere” in 29 CFR 1910.146 as an atmosphere containing “in excess of 10 percent of its lower flammable (or explosive) limit, airborne combustible dust that meets or exceeds its lower flammable limit (approximated as obscuring vision to five feet or less), oxygen concentrations below 19.5 percent or above 23.5 percent, or concentrations in excess of the OSHA Permissible Exposure Limits (PEL’s) for a substance.
In reality, we may set our levels of concern at even more stringent levels if the situation warrants and the levels of concern are stipulated on the entry permit. For instance, we may set our level of concern for toxicity at the NIOSH Recommended Exposure Limit (REL) for a substance or substances, as the RELs are normally more stringent (lower in concentration) than the PELs.
The “usual suspects” for toxic gases or vapors in permit-required confined spaces are hydrogen sulfide and carbon monoxide. Hydrogen sulfide is commonly known as “sewer gas” and results from the decomposition of organic material. It is both toxic and flammable. Carbon monoxide may also be present due to the occurrence of incomplete combustion and can even result from nearby apparatus or powered equipment exhaust. Due to this fact, most four gas meters used for permit-required confined space air monitoring are set up with sensors detecting oxygen concentration, flammability, concentration of hydrogen sulfide, and concentration of carbon monoxide.
Many misunderstandings of 29 CFR 1910.146 exist among emergency responders. One common theme is that emergency responders hold to the belief that since Part 1910 of 29 CFR pertains to general industry; it does not apply to emergency operations. In actuality, it does as our very lives depend on compliance with the Standard and our organizations can be cited and fined for non-compliance. A second misconception that is prevalent within the general industry community is that confined space permits have to be submitted for approval by another entity, similar to building permits when constructing or renovating a structure. Confined space permits are not required to be approved by anyone other than the Entry Supervisor and actually serve as a form of checklist that “keeps us honest” by documenting our actions and stating the acceptable entry conditions. It also benefits emergency responders to know that OSHA has also promulgated a Permit-Required Confined Space Standard for the construction industry in 29 CFR 1926.1204. Air monitoring in the construction setting is required on a continuous (or periodic under certain situations) basis.
Another area in which the realms of hazardous materials response and technical rescue operations collide in the area of air monitoring is that of trench rescue and recovery. OSHA defines a trench in 29 CFR 1926, Subpart P as “a narrow excavation made below the surface of the ground, with the depth being greater than the width and the width at the bottom of the trench not exceeding 15 feet.” OSHA states that where any hazardous atmosphere or oxygen deficiency exists — or could possibly exist — air monitoring shall be performed prior to the entrance of personnel into the trench in which the depth of the excavation is greater than four feet deep. A difference between 29 CFR 1910.146 and 29 CFR 1926 Subpart P exists in the air monitoring levels of concern. While OSHA states that the level of concern for flammability in permit-required confined spaces is greater than ten percent of the LFL/LEL, in trench environments the level of concern is stipulated as greater than twenty percent of the LFL/LEL.
As stated earlier in our discussion, organizations with both a hazmat team and technical rescue team can benefit greatly from cross-training in both areas. If at least a couple of hazmat technicians can be dispatched to perform air monitoring at confined space and/or trench incidents, all can benefit from the knowledge possessed by the hazmat personnel in the areas of air monitoring and the equipment used for monitoring. Oftentimes, at least a small number of personnel on technical rescue teams will have had hazmat technician certification and experience prior to transferring to the technical rescue side of things and can serve as valuable force multipliers for air monitoring.
As can be witnessed above, the worlds of hazardous materials and technical rescue can and do collide in the realm of air monitoring at confined space and trench rescue/recovery incidents. With an appropriate understanding of the pertinent OSHA requirements and air monitoring procedures, we can ensure the safety of our personnel and possible victims; and the success of our operations. As always, stay safe out there and be sure to visit the North Carolina Association of Hazardous Materials Responders website at www.nchazmat.com.