Air Monitoring on the Fireground: A Necessity, Not an Option


Most departments are carrying atmospheric monitoring equipment not only on their hazardous materials response units but also on most of their first-out apparatus. When asked why they carry meters, personnel commonly respond, “To respond to confined space emergencies or carbon monoxide (CO) calls.” But, if we think about it, CO calls are limited at best and rarely, if at all, do we run a confined space emergency. You might think I am advocating removing the atmospheric monitoring equipment from the trucks, but I am proposing just the opposite. We are missing the largest category of calls we respond to other than false alarms and medical calls—calls involving smoke and fire, which have one of the most dangerous environments we frequently encounter.

The multigas detector can help us do our job more quickly, efficiently, and safely. It is commonly used for hazardous materials and rescue incidents, but many departments are not using this tool to its fullest.


If the fire service were to begin to take a risk-based approach to fires, such as that used in the hazmat response discipline, many believe we would see our injuries, illnesses, and line-of-duty deaths decline. This issue can be summed up quite simply: If we are wearing self-contained breathing apparatus (SCBA) because we are in an immediately dangerous to life and health atmosphere, then why aren’t we checking that same atmosphere before we remove our SCBA? The answer is that we have let the bad habits of yesterday influence our decisions of today. For decades, American firefighters have accepted the toxic and asphyxiating products of combustion as “just smoke.”

Hazmat response focuses on safety through the use of risk-based response processes and procedures. Many of the safety measures in place today on the fireground were established by the hazmat community years ago. Think of the common residential structure, and compare it to a hazmat incident. The entry crew on the hazmat scene is on air before they enter the hot zone. On the fire scene, it is not uncommon to see firefighters connecting regulators as they are well past the threshold of the front door or are working on the roof during ventilation operations. Taking the safe approach, those firefighters would mask up while in the front yard, not at the front door.

Initial training has taught firefighters to wait until the last minute to go on air in an effort to conserve air in their SCBA. Now that the National Fire Protection Association (NFPA) 1404, Standard for Fire Service Respiratory Protection Training, is in place and the Rules of Air Management have been developed, firefighters can better manage their air without worrying about the two or three breaths on the front end. Firefighters must know that the cylinder is full before starting the shift; must manage their air while wearing the SCBA; must take responsibility for themselves and not rely on others to track their air; must know not to use the reserve; and, most importantly, must know to use the SCBA when in the presence of smoke.1 Changing that culture will be difficult, but it is extremely important if we are to protect ourselves against breathing in the harmful products of combustion.

Everyone has witnessed the firefighter who removes his face piece as soon as the fire is knocked down and the nozzle is shut off. For some reason, the fire’s extinguishment has been translated into an “all clear to remove SCBA.” Even with the visible smoke removed from the structure, toxic gases are still likely to be present. These gases are invisible, and you cannot smell them. The only way to determine if the atmosphere is safe enough to remove your SCBA is to monitor the atmosphere.

Once we better understand the science behind the smoke and better educate our firefighters, the safer we will be. If we teach our firefighters about the dangers of smoke and the health risks of being exposed to smoke both in the short term and long term, we will better prepare them. Compare the amount of time spent in recruit school learning about fire extinguishers and the amount of time spent learning about fire, smoke, and the products of combustion. This is not to say what we learn about extinguishers is not important, but we need to increase the amount of time spent on smoke, as it directly impacts the long-term health and safety of our personnel.

Most departments carrying multigas detectors are probably running the standard complement of sensors: oxygen, combustible gas, carbon monoxide, and hydrogen sulfide (O2, LEL, CO, and H2S, respectively). When firefighters are asked why their department carries that complement of sensors, they often respond, “Because that’s what the Occupational Safety and Health Administration (OSHA) confined space standard says.” Yet, the OSHA 1910.146 standard never mentions H2S. It does mention in part (d)(5)(iii) that when testing for confined space atmospheric hazards, test first for oxygen, then for combustible gases and vapors. It mentions measuring toxicity but never H2S specifically. One could argue that the fire service has allowed our lack of knowledge of the OSHA standard to dictate what we purchase in respect to sensors.

During my career, I can recall my department’s responding to only one actual confined space emergency; it involved a worker being stuck inside a carnival ride. H2S was not a concern, since there was no decomposition of an organic material, yet all the meters were set up with the typical configuration. I am not advocating removing all the H2S from the multigas detectors, but I suggest that departments evaluate the need for these sensors in every multigas detector. Carrying a meter with an H2S sensor on a technical rescue unit is a likely choice, but it may not be the most practical choice on the first-out engine.


In 2008, my department identified a need to add the capability of monitoring for hydrogen cyanide (HCN), a common gas found in the combustion process. To fill an immediate need, we purchased 10 single-gas meters to complement the existing multigas detectors. Now, the department is looking to upgrade its metering capability, and the HCN sensor will be included in the multigas detector for most of the units. The rescue companies and the hazmat unit will continue to carry the H2S for the confined space emergencies because it is a common gas in some instances.

Evaluate the calls your department runs where atmospheric monitoring is needed; then determine the gases you need to monitor. Typically, they include CO alarms and suspected CO poisoning, smell of natural gas, suspicious odors, and calls involving smoke. Most people leave out the last one, but that is beginning to change with more awareness and education. Some fire departments look for CO during the overhaul process, but that is limited at best; an even smaller percentage look for HCN.

Although hundreds of chemical compounds are produced during the combustion process, we can easily detect and treat exposures to CO and HCN. Likewise, it should also be recognized that the absence of CO or HCN does not mean that other harmful gases, vapors, and particulates are not present. There is a wealth of information about how the “Toxic Twins,” CO and HCN, can work together to debilitate the human body. CO attacks the blood by limiting the amount of oxygen to be transported, and HCN attacks the heart and lungs.2

Changes in sensor configuration can be a fairly inexpensive fix either by replacing existing sensors in multigas detectors, such as HCN in place of H2S, or adding a single sensor unit to complement the existing meters in your department. Other common gases of interest may be the oxides of nitrogen, aldehydes, chloride, and phosgene. It would be impossible to detect all the fire gases present, but looking for those that can affect us the most is a great place to start. There are even meters now that will list a library of gases found in overhaul. These meters tend to be a tad expensive, but they are extremely useful.

Although the National Institute for Occupational Safety and Health recommended exposure limits (RELs) for CO and HCN are 35 parts per million (ppm) and 4.7 ppm, respectively, some departments are opting to raise the bar and set their action levels at zero. This is a decision that needs to be established in the department’s guidelines so that everyone is clear what the action levels will be on the fireground. Although setting an action level is important, all personnel must know what the levels are and that they are properly enforced.


It is the incident commander’s (IC’s) responsibility to ensure air monitoring has taken place prior to personnel’s removing their SCBA. This task on the fireground should be a priority and as important as conducting a personnel accountability report, securing utilities, or establishing a rapid intervention team. These functions all lead to a safer fireground, which is the IC’s ultimate responsibility. That being said, individuals must be responsible for themselves and not fall prey to bad habits or peer pressure. Often, firefighters will remove their face pieces as a result of peer pressure because the other firefighters or, worse, their officers did.

It tends to work best if the meters come off the truck immediately along with the thermal imaging cameras, pike poles, and flashlights. They should be dropped at the incident command post when the accountability tags are dropped off or the personnel check in for an assignment. Taking them into the fire would be impractical, but by sitting the meters in front of the IC, the IC is reminded of a task that needs to be completed. If left running at the incident command post, the meters will act as a safety measure to alert the IC if the post is too close to the fire. From there, the IC can have the meters deployed into the structure when it is ready to be checked. If the meters are left on the rig, they are out of sight and out of mind and most likely will be left there.

If everyone receives the basic training on how to operate the meters, any crew member on the scene can use them, not just those to whom they are assigned. This helps if the company responsible for the meters is assigned to another task or is in rehab when the IC is ready to monitor. This task is usually coordinated with the ventilation group. When the group believes the structure is clear of all smoke and gases, the meters are sent in to confirm. Sending the meters in before the visible smoke is removed is not necessary, and it will typically be an unsafe environment, so don’t waste time and saturate the meters.

When atmospheric monitoring programs were initiated in fire departments, crews quickly realized what they once thought was safe was actually still dangerous. The use of atmospheric monitoring on the fireground will also lead to improved ventilation efforts. Positive-pressure fans tend to run a little longer and usually last long into the overhaul process and even into the investigation of the fire.

The meters can also be assigned to personnel in staging or with the rapid intervention crew. They are usually set up in the front yard of the structure or scene assisting with fireground activities in close proximity to the structure. It is typical to see these crews staged in the smoke for 15 or 20 minutes until the call is placed under control; all the while they are breathing in the harmful products of combustion. Then should something go wrong, these same individuals spring into action, not realizing they have been exposed and are not operating at peak performance.

It is important when training firefighters about atmospheric monitoring at fires that you monitor all calls involving smoke, not just working fires. Some of the highest readings will be at small pot-on-the-stove calls, where the fire may be extinguished prior to the first unit’s arrival. All it takes is a little heat to start to break down the glues in countertops, the plastic handle on the pot, or the side of the microwave next to the stove to produce these gases. In these smaller fires, there is enough heat to release the gases, yet not enough heat to use those same gases as additional fuel, thus leaving the gases unburned in the enclosed space for everyone to breathe.

Ensure the call for monitoring on the fireground is communicated over the radio so everyone is aware that it is taking place. This will act as a reminder for those who have fallen back on bad habits and prematurely remove their face piece. It will also remind crews of the importance of this step taking place on the fireground; it is no different from completing a primary or a secondary search. Once the metering has taken place, communicate the readings over the radio, if possible—more importantly, notify the crews on the fireground that personnel are cleared to remove their SCBA.

Monitoring on the fireground is an important step in running a safe incident. Properly using all personal protective equipment, SCBA, and atmospheric monitoring on every scene involving smoke is a must. We must no longer rely on what we “think” is safe and must dispel the “just smoke” assumption. The fire service must start to realize that air monitoring on the fireground is a requirement, not an option. Visit the Fire Smoke Coalition Web site ( for ideas on how to start monitoring in your department today.


1. Air Management (video recording), 2010, Media Sauce Productions.

2. The effects of these two gases on the body are described in more detail in “Cyanide: Fire Smoke’s Other ‘Toxic Twin,'” FireEMS, Fire Engineering, December 2011. Additional information is at

JASON KRUSEN is the special operations chief for the Columbia (SC) Fire Department, where he has served for more than 18 years. He is the president for the Board of Directors for the Fire Smoke Coalition. He has an associate degree in fire service administration. He is a planning manager with State Urban Search and Rescue Team, SC-TF1, the team coordinator for the Type II Collapse Search & Rescue Regional Response in Columbia, and a Planning Section chief for the Midlands Regional Incident Management Team. He is also the project manager for E-Med Training Services, LLC.

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