BY ROD HANDY, DAVID NEWELL, BRYAN DUNN, and WENXU YANG
The ability to properly use a four-gas air monitor is essential for those who respond to incidents involving hazardous materials releases. Typically, the first responder to the scene of a release is from the local fire department. Firefighters should be trained at a level to use their tools such as the four-gas monitor to properly characterize the incident and to make informed decisions based on the best interest of the public. However, there have been questions about whether the normal internal protocols for becoming familiar with and using the four-gas monitor develop an adequate level of competency for first responders.
Following is a discussion of the findings of a study involving a survey of a sample of hazardous materials first responders from a selected number of fire departments in the United States. The survey asked eight germane questions involving the setup, use, and interpretation of the values outputted from a common four-gas monitor. One hundred and eighty-five first responders from several municipal and volunteer fire departments were surveyed. Although some of the results found were promising, others were somewhat alarming. The study results revealed a need for more detailed training for first responders on the proper setup and use of four-gas monitors during an incident field characterization.
The Four-Gas Monitor
The four-gas monitor is an essential tool for those emergency responders who respond initially to an incident involving potential chemical exposures and anoxic or flammable atmospheres. The typical four-gas monitor has a chemical sensor each for percent oxygen (O2), percent lower explosive limit (LEL), concentration [parts per million (ppm)] of carbon monoxide (CO), and concentration (ppm) of hydrogen sulfide (H2S). First responders are required to take initial and refresher training on the use of these instruments. However, because of the inherent technical and scientific nature of these instruments, it could be argued that many first responders do not have the necessary background or training to make an accurate and timely decision based on the values measured.
The objective of this study was to survey a sample of first responders from volunteer and career fire departments in the United States. Our objective was to determine whether or not the typical first responder has the knowledge and competency to react as needed based on the monitor’s readings.
Training and competence are so interrelated that it is difficult to distinguish between the two. Competence comes from acquiring the knowledge, and specific training is used to narrow the gap between inconsistency and consistency. Performing tasks and establishing competency can be as simple as children practicing their ABCs in school until they are able to write complete sentences with meaning as they progress. Emergency responders’ competencies are learned much the same way. Through years of education and hands-on training, these heroes of our society bring resolution to some of the worst moments experienced by the general public.
During our prestudy conversations with training personnel, industrial hygienists, and instructors of HAZWOPER or Hazardous Material Responder training courses, a clear message became prominent: Many first responders, when asked to perform tasks on a yearly basis, couldn’t accurately complete the task or, at a minimum, needed additional refresher training to accomplish just the minor monitoring activities and interpretation. The personnel operating these monitors must be able to read the values and make an assessment on whether it is safe to occupy or enter a particular place after an incident has occurred. In essence, the first responder must be competent enough to make potentially life-and-death decisions based on the limited information these instruments provide regarding the ambient air conditions in close proximity of an incident.
When addressing potential life-and-death decisions based on monitoring competencies, we tried to identify competencies/inadequacies for responders during the monitoring of hazardous environments using four-gas meters. The intent of this study was not to discredit individuals or their capabilities; it was completed solely to provide a unique perspective of personnel as they monitor potentially hazardous or immediately dangerous to life or health (IDLH) atmospheres or environments.
Other professionals have recently addressed this question of competency for emergency responders and the need for more training on the proper use of equipment and instrumentation.1,2 These guiding principles are also covered thoroughly in the U.S. federal standards for protecting the environment and worker.3,4 Both Occupational Safety and Health Administration (OSHA) HAZWOPER (29 CFR 1910.120) and Environmental Protection Agency (EPA) (Title 40, Part 311) regulations give requirements for competencies of personnel who respond to hazardous materials incidents, including those for air monitoring. Responders must be able to assess the hazards and take appropriate actions based on the incident facts regardless of their response discipline and as the scope of standards applies.
The need for trained responders during incidents of all types is of vital importance. Organizational standard operating procedures (SOPs) may provide some guidance for responder competencies and, regardless, organizations must train personnel to meet National Fire Protection Association firefighter standards for certification.5 Local communities are responsible for protecting their citizens from hazardous materials, which includes identifying the resources necessary for mitigating an emergency. Local officials have the lead role in responding to emergencies involving the release of hazardous materials, with specific responsibility being in the care of the local fire departments.6 Thus, this reality places the burden on local governments to supply trained personnel and hazardous materials incident management capable of properly using the tools available to them for incident characterization, control, and management.
A vital part of the first responder’s job involves the identification of hazardous materials through the use of container shapes and sizes, identifying markings, interpretation of data from safety data sheets (SDS) and monitoring of the atmosphere. In most instances, local jurisdictions rely on the fire service to perform this action. Monitoring of the environment ensures that citizens as well as responders are protected from hazards. This monitoring includes hazards that are used in industry and are transported. In addition, monitoring activities may include controlled environments, such as homes and products associated with fossil fuel consumption. Furnaces or cooking stoves as well as generators for electrical power, which burn natural gas, propane, gasoline, diesel, or charcoal, produce carbon monoxide and other deadly by-products that are classified as hazardous materials. Many deaths are attributed to carbon monoxide every year; causes vary from improper use to lackluster maintenance procedures.
First responders must make informed decisions involving life-and-death situations, often in a very chaotic environment. These decisions are based on their abilities to use the assigned equipment correctly, with speed and accuracy. Failure to make the proper decisions may result in a worst-case scenario of lives being lost or the evacuation of a facility when it didn’t need to be evacuated. The shutting down of major thoroughfares, evacuation of residents, and life safety all cost money, and the inability or ability to make informed decisions will be reflected in those costs.
This study’s hypothesis was that most first responders using a four-gas monitor do not understand its basic principles of operation or how to interpret the values measured. This includes confusion, misunderstanding, and misinterpretation associated with monitor outputs, operation, units, alarm settings, and calibration. The following section provides the methodology chosen to test this hypothesis and to address the issue of competency. The methodology section is then followed up with sections that include the data and results realized as well as the conclusions and recommendations from the study.
Methodology
A competency study was conducted involving first responders in the fall of 2014 in a large metropolitan area in the Southeast United States. The competencies that were evaluated involved the operation of a typical four-gas atmospheric monitor and the interpretation of the measurements. The instrument used was an eight-question questionnaire designed to test these competencies.
The first responders assessed were from a municipal fire department consisting of career first responders, a small-town fire department consisting of career and volunteer first responders, and an all-volunteer fire department. Since there are many brands and models of four-gas monitors on the market, the eight questions developed for the survey were very generic in nature and were germane to all of the monitors available on the market today. One hundred eighty-five subjects were surveyed for this study.
The test subjects were in a controlled classroom environment. They had no foreknowledge of the survey. Once briefed, participants were then directed to turn over the question sheet, which they were given 2½ minutes to complete. No identification markings were made or attempted for each of the surveys because the survey is not to be used for judgment or criticism of the test subjects by their respective administrative staffs. The survey results were not supplied to any of the participating departments.
Some study variables existed and were accounted for with best practice; however, they could not accurately be used as a 100-percent, proof-positive guideline. For example, four-gas monitors use different calibration gases for meter calibration in response for flammable/explosive atmospheres. Because of anonymity, we chose to select any of the possibilities that may be used for this calibration procedure. The participants may have produced a correct answer based on this but may have had the incorrect answer based on the monitor and gas used by their organization. The number of these types of data biases was minimized for this study.
Data and Results
The following paragraphs begin with the questions asked followed by the documented results from the participants. Since four particular gases are monitored by each instrument, questions 2 ,3, and 4 each have four correct answers. The analysis of data was broken down into all four parts and combined as one question. There were four potential answers multiplied by 185 test subjects, resulting in 740 possible correct answers. The various fire departments used different toxic sensors-for example, some departments use H2S, and others use hydrogen cyanide (HCN); still others may use something different. Thus, any toxin listed (other than CO) would constitute a correct answer.
Questions 1 and 8 – How long have you been an emergency responder?
This question was explained prior to the start of the survey. Instructions were given to include whether their department was career, volunteer, or a combination of the two. Any answer was acceptable. The participants knew what the question was before they turned over the survey and did not spend time figuring numbers for their service to the community. This did not hamper their abilities in answering the pertinent questions about the monitor.
Question 2 – What four gases does the monitor measure?
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| Figure 1. Gas Identification Accuracy |
A first responder should be able to list these without any difficulties. The gases could be listed in any order. Some departments use H2S while others use HCN or another chemical sensor specific to the gas of their concern; thus, any toxin listed, with the exception of CO, was counted as a correct answer. Out of 740 possible correct answers, the participants responded correctly 565 times and incorrectly 175 times. This equates to 76.35-percent correct responses and 23.65-percent incorrect responses (Figure 1). If you break the data down to each specific sensor, the percentages of correct responses follow: O2-87.03 percent, LEL-63.24 percent, CO-89.19 percent, and a specific toxin-66.95 percent.
Question 3 – What units (ppm or percent) are used for each of the four gases?
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| Figure 2. Units Identification Accuracy |
The answers supplied reflected the gases listed in Question 2. The answer should also have represented knowledge of the four gases and the interaction with the monitoring device. Out of 740 possible responses, 412 of the questions were answered correctly; 328 were incorrect in their response. Thus, the survey responders answered correctly 55.68 percent of the time and wrongly 44.32 percent of the time (Figure 2). The breakdown of the correct responses for each sensor follows: O2– 64.32 percent, LEL- 45.95 percent, CO-65.95 percent, and toxin-46.49 percent.
Question 4 – What are the alarm limits for the four gases (ppm or percent)?
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| Figure 3. Alarm Level Identification Accuracy |
The answers supplied reflected the gases in Questions 2 and 3. The answer also represented knowledge of the four gases and the interaction with the monitoring device. This also represents knowledge of the particular hazards associated with each of the four gases and their response levels. Out of the potential 740 results for this question, 175 of the answers were provided correctly, with 565 of the answers being incorrect. The percentage of correct responses was 23.65 percent, with the percentage of incorrect responses being 76.35 percent (Figure 3). The breakdown of the correct answers for each sensor follows: O2-10.27, LEL-32.43 percent, CO-40.54 percent, and toxin-11.35 percent.
Question 5 – What is the calibration gas used to obtain the LEL reading for your monitor?
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| Figure 4. Calibration Gas Identification Accuracy |
Four-gas monitors use different gases for calibration in response to flammable/explosive atmospheres. Because of anonymity, the participant may have produced a correct answer for the survey but may actually have had the incorrect answer based on the monitor and gas used by the organization. Out of 185 surveys, 68 respondents answered this question correctly. This equates to 36.75 percent of those surveyed who were able to identify a suitable calibration gas for LEL (Figure 4). Some respondents did not respond or listed a toxin (e.g., identified HCN as the calibration gas for explosive/flammable limits).
Question 6 – How often is your monitor bump tested and/or calibrated?
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| Figure 5. Bump Test or Calibration Determination Accuracy |
The research team could quickly verify with the test subjects’ organizations, but because of anonymity and the answer variances, a large selection of criteria was available for the correct answer. Perhaps the most compelling point is that the test subjects realized and understood what the question asked and, therefore, supplied an answer unless a clearly wrong answer was provided. Out of the 185 respondents, 155 answered this question correctly. This equates to 83.78 percent of those surveyed being able to identify a specific time when the monitor is bump tested and/or calibrated (Figure 5).
Question 7 – When would you do a fresh air calibration?
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| Figure 6. Fresh Air-Calibration Determination Accuracy |
This answer varies, since a large selection of criteria was available for the correct answer. Typical correct answers included the following: each use, when the numbers start reading negative, daily, and before entering an area. Out of the 185 surveyed, 134 respondents answered this question correctly. This equates to 72.43 percent of those surveyed being able to identify a time or a reason for a fresh air calibration (Figure 6).
Conclusions and Recommendations
The following are some of the pertinent conclusions and recommendations from the study:
- For the identification of O2 and CO as two of the correct gases, the respondents scored 87 percent and 89 percent, respectively. Firefighters respond to a great volume of calls involving potential carbon monoxide releases; first responders perhaps use O2 and CO monitors most often. The respondents fared pretty well on the questions regarding bump/calibrate and fresh air calibration. They were able to answer these questions correctly 83 percent and 74 percent of the time.
- There was a lack of understanding among those surveyed concerning how the monitor reads some of the gases in ppm and others as a percentage. This was evidenced by a decrease to an average of 55 percent of correct responses on this question.
- There was an even more dramatic drop in understanding of the aspects regarding instrument alarms. The respondents answered this question with only a 23.5-percent correct response rate.
- Thirty-six percent of the survey test subjects identified correctly which gas is used to calibrate the monitor for LEL. This is a serious issue because the analysis of the data requires using correlation charts based on the calibration gas for conversions.
- It is recommended that each department survey those members who are required to use a gas monitor to assess their capabilities and individual needs regarding the proper use of and the interpretation of the results realized by the four-gas monitor.
Without a thorough statistical analysis of the data, it cannot be proven (or disproven) that the first responders lacked all of the competencies required to properly use a four-gas monitor in the field. However, even without a mathematical analysis, it can be argued that the hypothesis of the study was supported for some aspects studied regarding first responder competencies and the use of a four-gas monitor. Only five of the 185 participants surveyed scored a perfect score.
From the data gathered in this study, there appears to be a lack of general competence among first responders when it comes to air monitoring with a typical four-gas monitor or when questioned about its proper use. A lack of knowledge could prove devastating in a courtroom or can compromise public health and safety as well as the safety of the first responders. Based on the information garnered in this study, first responders should receive more detailed and more frequent training with regard to the atmospheric monitoring of the ambient air near an incident. Competence levels should be verified to minimize the potential for future serious injuries or deaths during a response to a hazardous materials incident.
Endnotes
1. Noll, G. (2008, April 1). “NFPA 472: Developing A Competency-Based HAZMAT/WMD Emergency Responder Training Program,” Fire Engineering, 161(4). Retrieved from http://emberly.fireengineering.com/articles/print/volume-161/issue-4/features/nfpa-472-developing-a-competency-based-hazmat-wmd-emergency-responder-training-program.html.
2. Wagner, D. (2006). “Do’s and Don’ts of Atmospheric Testing,” Asia Pacific Fire, (19), 71-73. Retrieved from http://www.indsci.com/docs/Press/APF_0906.pdf.
3. U.S. Environmental Protection Agency (USEPA). Worker Protection, 40 C.F.R § 311 (2011).
4. U.S. Occupational Safety and Health Administration (USOSHA). Hazardous Waste Operations and Emergency Response, 29 C.F.R. § 1910.120 (2007).
5. NFPA 472: Standard for Competence of Responders to Hazardous Materials/Weapons of Mass Destruction Incidents. (2013). Retrieved January 11, 2015, from http://www.nfpa.org/codes-and-standards/document-information-pages?mode=code&code=472.
6. Guidelines for HazMat/WMD Response, Planning, and Prevention Training, Federal Emergency Management Administration, (2003, April). Retrieved February 6, 2015, from http://www.usfa.fema.gov/downloads/pdf/publications/hmep9-1801.pdf.
ROD HANDY, MBA, Ph.D., CIH, is a professor in the William States Lee College of Engineering at the University of North Carolina Charlotte (UNCC). He has nearly 30 years of experience in environmental and occupational health and safety engineering.
DAVID NEWELL is a faculty member in Fire Protection Technology at Davidson County Community College in North Carolina and a graduate student in the Master Fire Protection Administration (MFPA) program at UNCC. He has nearly 25 years of hazmat experience.
BRYAN DUNN is the chief of the Harrisburg (NC) Fire Department and a graduate student in the MFPA program at UNCC. He has 27 years of fire service experience.
WENXU YANG is a graduate student in the MFPA program at UNCC.
How to Mitigate Human and Mechanical Errors Using Gas Detectors
BY BRIAN CRIMMINS
On November 14, 1996, a gas company technician responded to a reported odor of gas call at the Humberto Vidal shoe store in Río Piedras, Puerto Rico. The San Juan Gas Company technician entered the building, turned on his gas detector, and surveyed the area. Despite complaints of a strong odor, the gas detector did not reflect any hazardous readings. Days after the technician left, there was an explosion that killed 33 and wounded 69 others. Investigators from the National Transportation Safety Board (NTSB) determined that propane gas from a cracked pipe caused the explosion. The NTSB also determined that the technician failed to identify the gas leak because he did not use the gas detector properly. He turned on the detector while already in the hazardous environment and never recorded a fresh air sample. He was, therefore, unable to record dangerous levels of the explosive gas. Failures by other investigation crews also contributed to the disaster.1
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| (1) Four-gas meters are commonly used by firefighters. (Photo by Brian Crimmins.) |
From the tragic lesson of the Río Piedras explosion, we can learn that the proper use and maintenance of gas detectors are critical to the safety of firefighters and to the people we protect. This article is not an analysis of the chemistry behind explosive gases or a set of procedures for responding to gas calls. Rather, it should serve as a summary of how to mitigate the human and mechanical errors commonly associated with the misuse of gas detectors.
Human Error
To begin, all firefighters should know what types of gas detectors their company carries. In terms of combustible gases, this question is slightly more complicated than the simple “photoionization detector (PID) vs. flame ionization detector (FID)” many firefighters discuss. In fact, the MSA Gas Detection Handbook, 5th edition, lists six common technologies for combustible gas detectors alone.2 Each detection method has different advantages and limitations.
Firefighters should study manufacturer specifications and user manuals that address the specific gas detectors in service on their apparatus, including best practices, limitations, safety, and proper maintenance. If the department has not provided copies of these materials, firefighters can often access them online. Firefighters should also routinely train in basic skills like sampling high and low areas for gases lighter and heavier than air. Also, firefighters should know the proper speed to use when collecting air samples. Remember that detectors have unique response times that address how long it takes for gas pulled into a probe to travel through tubing and reach the sensor.
Next, fire departments should draft standard operating procedures (SOPs) that address response procedures for different types of gas emergencies. Natural gas, propane, carbon monoxide, and industrial chemical releases all involve different gases with unique properties and hazards. SOPs should specifically identify the hazards (toxic, explosive, corrosive, and so on) associated with each gas they are likely to encounter and specific thresholds of when to take precautionary actions such as evacuation and ventilation. SOPs should also address other basic precautions: wearing the proper protective equipment, calling the utility company, taking fresh air samples, eliminating ignition sources, repositioning apparatus, surveying exposures, and so on.
Finally, firefighters must train on using correction factors to interpret gas detector readings when monitoring for other materials than the calibration gas. It’s important to remember that gas detectors are calibrated to read one specific combustible gas (e.g., methane, pentane). If the detector is used to sample for another gas/vapor that is different than the calibration gas, the readings will be slightly skewed because of the differences in chemical properties. To compensate for these differences, instrument manufacturers will provide correction factor charts. The correction factor is the ratio between the gas the detector is calibrated to and the gas that the detector is sampling. For example, if the correction factor for acetone is 1.54, then a reading of 10 percent lower explosive limit (LEL) should be multiplied by 1.54 to have a more accurate reading of 15.4 percent LEL. When possible, firefighters should carry laminated correction factor charts on their apparatus.
Mechanical
The most common mechanical errors with gas detectors result from failure to properly conduct bump tests and calibration. According to the Occupational Safety and Health Administration (OSHA) and the International Safety Equipment Association (ISEA), a bump test is a “function check.”3 This ensures that the gas detector’s sensor is not blocked by water, dirt, or some other obstruction. The purpose of the bump test is to ensure that a test gas reaches the sensor and activates an alarm. According to the ISEA, bump tests should be performed daily.4
Unlike a bump test, a calibration check tests a gas detector’s accuracy. This is a quantitative test to ensure that the gas detector records the accurate amount of gas and alarms appropriately when exposed to a known concentration of test gas. (4) Calibration checks ensure that the gas detector is working properly. Two mechanical problems that can occur are sensor “drift,” where sensors slowly lose sensitivity over time, and sensor poisoning, where a contaminant impacts a sensor’s readings. (3) Specifications for periodic calibration checks vary according to the manufacturer and type of gas detector. Needless to say, failed calibration (as a result of sensor drift, sensor poisoning, or other damage) requires the gas detector to be placed out of service pending repair, replacement, or a “full calibration” to readjust the sensor to accurate levels.
The ISEA also recommends additional calibration checks after certain events. They include exposure to extreme high or low temperature or humidity; exposure to certain particulates, gases, or chemicals; exposure to extreme amounts of target gases; change in custody; impact from dropping a gas detector or submerging a detector in water; and other extreme and harsh exposures. Any of these events can impact a gas detector’s measurements and cause inaccurate readings. (4)
Finally, one basic step that will help to minimize both human and mechanical errors is to always use two separate gas detectors at the same time in the same environment. Firefighters should note any time gas detectors show significantly different readings in the same environment and perform calibration checks if necessary.
Gas detectors are complicated instruments that are prone to human and mechanical errors. Failure to properly handle or maintain gas detectors can cause firefighters or civilians to unknowingly enter toxic or explosive environments, with catastrophic consequences. We can mitigate these errors through proper SOPs, training, and maintenance. Firefighters and civilians will be safer by following the appropriate precautions.
Endnotes
1. http://www.ntsb.gov/investigations/AccidentReports/Reports/PAR9701.pdf.
2. http://www.gilsoneng.com/reference/gasdetectionhandbook.pdf.
3. https://www.osha.gov/dts/shib/shib093013.html.
4. http://www.safetyequipment.org/userfiles/File/calibration_statement-2010-Mar4.pdf.
BRIAN CRIMMINS is a battalion chief and hazardous materials technician with the Hoboken (NJ) Fire Department. He has a BA degree from Boston College and an MPA degree from John Jay College.
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