Air Monitoring Part One

(This is part one of a two part series.)

Before you turn the page and skip this article because you saw the words “air monitoring” or “hazardous materials,” stop and give it a chance! Please leave any preconceived notions you may have about what this article might be about.


While I generally write about hazardous materials for hazardous materials team members, this is not one of those. This article is designed for regular firefighters. And as we will see, you really are involved in hazardous materials response from a certain point of view, even if you don’t realize it. The vast majority of firefighters joined the fire service to fight fire or perform technical rescue, not respond to hazardous materials incidents. The fact remains that the same materials that are regulated as hazardous materials are commonly found in structure fires.

With that being said, please keep the following in mind as you read this article:

  1. If you can use a smart phone, universal remote control or game controller for game systems such as Wii, Playstation or X Box, you can use a monitor.
  2. Anyone can do air monitoring as long as they have been trained and practice with their meter.
  3. Most monitors have fewer buttons than a game controller.
  4. Structure fires are indeed hazardous materials incidents from a certain point of view, so you do in fact need air monitoring.

Going back to the very first classes we took as rookies, we remember learning about the products of combustion found in smoke. We learned that these materials can have an adverse effect on our health, so we wear SCBA. These materials are all regulated as hazardous materials and include flammable liquids, poisons, corrosives, oxidizers, poison gases, non-flammable gases and others. You might not want to respond to a release of one of the materials at a fixed facility or transportation accident, but you have no choice when it comes to a structure fire as EVERY one of these materials is a product of combustion!

Air monitoring is only now being emphasized in fire suppression, as it should be. For many years, air monitoring during an emergency response was an afterthought, but it is now considered essential for personnel protection. It has also become quite simple. Air monitoring is performed to aid in hazard assessment and to ensure a safe atmosphere for the public, responders and the environment. Even if every firefighter were to don SCBA on every incident, the need for air monitoring would still exist. The same instruments can be used for hazardous materials incidents, technical rescues — confined space and trench — and structure fires. Portable air monitors can be a valuable tool in providing information that is vital to the success of the incident and the safety of emergency services personnel and civilians. You can also smell or see very few of these hazardous gases.

OSHA 1910.120 Hazardous Waste Operations (HAZWOPER) standard paragraph q (iv) states the following. If we follow the OSHA standard “to the letter” we would have to monitor the area before we allow our firefighters to overhaul a room — or enter a room for fire attack or a structure for recon — without wearing their SCBA. We have followed HAZWOPER for years pertaining to our hazardous materials training and response, but it has never really been applied to fire suppression. This is hard to understand given the earliest classes in fire behavior all mention the hazardous materials that are contained in smoke and the importance of wearing SCBA.

Monitoring equipment is made to protect and preserve your life! Each of these devices has fewer buttons than any of the game controllers from Wii, Playstation or X Box. The simplest single gas meter has one button. A MultiRae four-gas meter with PID has three buttons while a Radiac only has six. Some of your game controllers have more than a dozen buttons! Despite what you may think, or may even have been taught, you CAN use a meter!

When to Monitor

A natural disaster could involve natural gas, propane, carbon monoxide or sulfur dioxide. The brewing industry uses large amounts of nitrogen. Liquid oxygen is used in hospitals. Universities and laboratories may use a wide variety of hazardous materials depending on the type of lab. Confined space entries may confront hydrogen sulfide or an oxygen deficient atmosphere. Trench rescues may yield the same dangers as confined spaces. Oxygen and carbon monoxide are found in the steel industry. Ammonia can be found in the semiconductor and food processing industries in addition to any industry that has a large cold storage area. Monitoring can be a lifesaver when it comes to dealing with such things as leaking furnaces or gas lines. PIDs can also be used to check for trace amounts of accelerants during the investigations of fires with a suspicious origin. Air monitoring helps to prevent injuries and illnesses including poisoning from toxic gases, burns or internal organ damage.

As specified in OSHA 1910.146 Confined Space Standard, oxygen, flammability, carbon monoxide and hydrogen sulfide are required to be continuously monitored. The possibility of encountering hydrogen sulfide is also on the rise due to the increase in chemical suicides across the country. Hydrogen cyanide is only recently — within the last several years — being given the attention it deserves. Corrosives are the second most transported hazardous material. The possibility of a radioactive material being used in a radiation dispersal device (RDD) or dirty bomb must also be considered due to the threat of terrorism that we have been operating under since the events of 9/11 and we will continue to operate under for the foreseeable future.

Any time there is a gas leak in a building, we must thoroughly check the area with a combustible gas meter. Investigating without a meter is just not good enough. If the odorant has been scrubbed out of natural gas, the CO sensor may mistake high levels of natural gas for CO. A combustible gas meter is needed to detect the deodorized natural gas. Don’t commit all of your personnel to searching for the leak in the structure. Keep some outside in reserve. Often, personnel will become desensitized to the odor they are trying to locate. They may have noticed it upon arrival but lose the ability to smell it over the course of the incident. When this happens, it is time to deploy your reserves and it allows the first in companies a chance to clear their senses. If there is any reason to believe that the odor may be dangerous, evacuate the occupants as soon as possible and have all firefighters don SCBA. If you have an odor that you feel might be dangerous and you can’t find the source, contact your HazMat team or local gas utility. You may need EMS to check out or treat the occupants. Always notify the gas company of any gas leaks and of all valves that you have secured. Many utilities will want to check the entire system before they turn the gas back on. Never open a gas meter once you have shut it off. It is the responsibility of the gas company to restore service, not yours.


Once the LEL is exceeded, there is a fire hazard. Some meters will shut the LEL sensor off once the LEL is exceeded as the longer the sensor is exposed to an atmosphere above the LEL the faster it will deteriorate. Flammable and combustible materials are the leading category of hazardous materials transported and released. If an LEL sensor provides a reading of “1” then there is a flammable material released. If you cannot locate a liquid spill, then the reading is from a gas. If you find a liquid spill and the LEL sensor is reading, and as you get closer to the release the meter starts to climb, then the spilled material is flammable.


An oxygen deficient atmosphere is one where the oxygen content is less than 19.5 percent. This can be caused by another material displacing the oxygen, microbial action, oxidation and combustion. An oxygen-enriched atmosphere is one where the oxygen content is greater than 23.5 percent. If you have anything less than an oxygen concentration of 20.9 percent requires the use of SCBA. Increased oxygen concentrations increase the flammability risk of materials present. Oxygen sensors are influenced by the temperature of the atmosphere they are being used to measure. The warmer the atmosphere, the faster the response of the monitor. In temperatures less than five degrees F, correct readings may no longer be obtained.

As the oxygen concentration drops below 19.5 percent the human body reacts by reflexes, response time, judgment and other mental faculties slowing down. Oxygen enriched atmospheres are considered a fire risk. In oxygen deficient atmospheres, any combustible gas readings are also deficient and cannot be relied upon. In oxygen enriched atmospheres, the combustible gas readings increase and are not accurate. Oxygen sensors are the most frequently replaced because they are exposed to oxygen every time the meter is turned on.

Carbon Monoxide

When responding on a CO alarm, always wear full PPE including SCBA until the meter — not your nose — gives you the all clear. Take the first reading at the door and the second reading arm’s length inside the door. Then proceed to monitor throughout the structure, paying special attention to areas where furnaces, hot water heaters, gas dryers or gas logs are present. Also check around chimneys and flues as CO is a product of incomplete combustion. DO NOT ventilate the structure until you have had a chance to monitor the interior. Evacuate everyone from the structure and consider having EMS respond to check the occupants. If occupants are showing signs and symptoms, then EMS response is a must! Just because there are low levels of CO present does not mean that the corresponding level of HCN is also low.

Hydrogen Cyanide

HCN symptoms in lower level exposures are similar to those of heat-related illnesses and CO poisoning. HCN symptoms in severe or acute cases mirror those of a heart attack. Many health care facilities are not capable of testing or treating HCN poisoning. There are only a few labs in the entire country that have the capability to test for HCN levels in a blood sample. There is no antidote for cyanide poisoning. Suppression personnel are not properly trained on how to identify the symptoms of HCN. Statistical data are not available to help educate and protect firefighting personnel. It is believed that many deaths previously attributed to smoke inhalation or CO poisoning may have actually been caused by HCN exposure.

You may have heard or been taught that hydrogen cyanide has the odor of “bitter almonds.” What you may not know is that only 30 percent of the general population has the gene necessary in order to detect the bitter almond odor. If you don’t smell anything, is it because there isn’t any HCN or is it because you don’t have the necessary gene in your DNA? Don’t take the risk. The only way to detect or rule out the presence of HCN is by using a meter.

The signs and symptoms of HCN and CO are practically identical. An exposure to one may lead to a trip to the hyperbaric chamber while an exposure to the other may mean a trip to the morgue. You cannot rely on a diagnosis based on signs and symptoms alone. You MUST use a meter!


When pH goes from one to two, it is a drop by a factor of 10. A material with a pH of two is 10 times less acidic than one with a pH of one. A material with a pH of three is a hundred times more acidic than one with a pH of five. Chemicals with a pH of less than two or more than 11 present a significant risk for injury to humans. Corrosives are the second most transported and released hazardous materials behind flammables and combustibles.

The range of corrosives on the street is limited to a few common materials. If using multi-range pH paper, a color change to red indicates an acid being present. A color change to blue indicates a caustic material being present. If the pH paper changes above or away from the spill, then the material is a high vapor pressure material. Many acids are low vapor pressure acids and only indicate when the pH paper is dipped into the liquid.

The pH paper can easily be taped to a pike pole in order to monitor the atmosphere 10 or more feet in front of you. As soon as you see the pH paper turn color, stop where you are and drop a cone. This designates your Hot Zone until meters can better define the area.


According to news reports and FBI records, radiation events are on the increase. According to the Nuclear Regulatory commission (NRC) many people are murdered using radioactive sources each year and a number of radioactive sources are stolen each year. The most common theft is of ground imaging devices, which in some cases have significant radioactive sources that can cause harm to a community. The records of the NRC indicate that there are about 9000 devices missing in this country. When dealing with unidentified materials, packages, containers, drum dumps and other possible criminal activity it is very important to check for radiation. Radiation cannot be seen, felt, tasted or smelled. Like the other materials we have talked about, the only way to detect it is with the proper meter.

With terrorism on the rise, including plots to use radiation dispersal devices (RDDs) or “dirty bombs” responders need to be comfortable with the detection and monitoring for radiation. We are subjected to radiation exposure in various forms every day. It is when we come into contact with higher doses of radiation, either through accident or intentional misuse, that we must be prepared. Radiation doses should be kept “as low as reasonably achievable.” This phrase is known in the nuclear industry as ALARA and is the cornerstone of radiation safety. The three factors that can influence radiation dose are time, distance and shielding. These concepts should be applied to all types of chemical exposures as well. Radiation is comprised of two basic categories: ionizing and non-ionizing. Non-ionizing radiation includes radio waves, microwaves, infrared, visible light and ultraviolet light. Alpha, beta, gamma and x-rays are all forms of ionizing radiation. When turned on, a radiation monitor will pick up naturally occurring background radiation which should measure in microrem. The amount of background radiation varies from city to city and even varies within a few miles. It is important to do some testing to determine the normal levels in various parts of your community. Then responders can know when they are being exposed to radiation levels higher than background. These devices are sensitive enough to detect radiological pharmaceuticals such as those used in chemotherapy, so they may alert if in close proximity to someone who recently had chemotherapy.

Hydrogen Sulfide

Some people may not be able to detect odor in the same way that not all people can detect the odor of hydrogen cyanide. The temporary loss of smell is known as olfactory fatigue. Prolonged exposure may cause runny nose, cough, hoarseness, headache, nausea, shortness of breath and severe lung damage — pulmonary edema. Three hundred to 500 ppm yields excitement, severe headache, dizziness and staggering. Greater than 500 ppm, if not fatal, may cause long-term effects such as memory loss, paralysis of facial muscles or nerve tissue damage. Levels at or above 700 ppm can cause death immediate death with just two to three breaths.

Next issue we will continue this article with information on PIDs, SpilFyter strips, monitors and what you need to know about them and much more. All information that firefighters need to know.

Mark Schmitt is Captain/Hazmat Specialist for the Greensboro Fire Department in Greensboro, N.C., and a veteran of over 20 years in the fire service. The majority of his career has been spent in special operations. He is a graduate of the National Fire Academy’s Executive Fire Officer Program and holds a Master of Public Administration in Emergency Management. Schmitt has taught numerous hazardous materials courses for the Greensboro Fire Department, local community colleges and the North Carolina Office of the State Fire Marshal in addition to serving on several hazardous materials related committees at the local and state level.
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