I am wondering how many department's are monitoring for fire gases such as CO, HCN, H2S, etc? If so what does it measure and what are the departments action levels?

Does your department utilize air monitoring to determine the use of SCBA during operations?

More importantly, why did the department begin air quality monitoring and has it incorporated it into its SOP's and operational culture yet?


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We have an SOP to monitor for CO and use SCBA's. I have tried to get it defined fo post fires and SCBA removal with no luck. 50ppm of CO is a good number for removal during overhaul. However, most departments cannot and do not monitor for HCN. Cyanide is the off gass from all of the plastics. Guys have been out in the hospital due to this. Unless you know the area is totally clean, protect yourself no matter what you think everyone else thinks.
Mr. Brooks,

In your opinion, do you feel the fire service is aware of the dangers of CN? If not, how can we inprove the recognition of the respiratory hazards of smoke and the byproducts of combustion?
This is a great topic for discussion. Carbon Monoxide is something that some firefighter take for granted. Hydrogen Cyanide and Hydrogen Sulfide , and even oxygen levels should be monitorered in all atmospheres of the fireground operations before any SCBA is removed. A wise chief once said every building fire is a Haz Mat call, whether we realize it or not. Being that these toxic gasses would should little or no sign (scent or color) to its potential victims before they strike, it is an even more deadly game we play. Mr Brooks, it is great that your company has a SOP in place for CO, but you should have that SOP changed. 35 ppm of CO is considered a level that is a hazardous atmosphere. You should have all proper SCBA's on until the levels of CO, HCN and H2S are in the levels that are deemed safe.
We all learen lessons from other departments who make a mistake, whether through their own lack of training, or just forgetting. Providence Fire Department didn't have much of a HCN policy until their department was strikken with 2 station houses full of firefighters who had Cyanide Poisoning from a routine room and contents fire they overhauled without packs on.
My department has a Hzardous Materials Team, with some of the finest tools and trained personnel to use the equipment. We have Multi-Rae's which Measure CO, H2S, Oxygen levels, and we have Draager Tubes to Measure for HCN. If we all go home at the end of the day because we stopped to ensure the air we breathed was ok to be inside, than the 5 minutes it takes to monitor the air properly was well worth the effort. Stay safe out there
I have made numerous attempts at getting our SOP changed to reflect a numerical value for SCBA removal. I think 35ppm is to low and 100 is too high. I believe OSHA uses 50ppm for their TWA. That is what I would use. As far as qualifications go, I am a hazmat tech and team member. Have been for over ten years. We have all of the toys as well. We do use our tubes since they are much less expensive than other tools and have no maintenance other than replacement when expired. We tend to only use them when searching for knowns. HCN would be a great use of colorimetric tubes since they are relatively cheap and require no calibration. I also agree that all fires are hazmat scenes. Firefighters in general have a false sense of security when the fire is out. Other than the actual fire, the smoldering/overhaul stage is probably the most dangerous air quality time due to off gassing and incomplete combustion. Too often I have seen guys take off their SCBA because everyone else did. That does not mean it is safe or the right thing to do. It is our job to take care of each other.

Now, the question about HCN in the fire service. I have gathered a ton of information on this topic to try and get metering equipment at my full time department. We have a regional hazmat team. They could be called for monitoring at fires if needed, but colorimetric tubes are cheap in the grand scheme of things. I have been trying, fairly unsuccessfully, to see if we could just change our 4 gas meter from HS to HCN. We have multiple meters, so changing one would not be a big problem. What I do not know is the life of a HCN censor. One of the main reasons we use tubes is that chlorine sensors are only good for 6 months. If the HCN sensors are short lifed, they make no sense to have. Tubes are more cost effective. I hope this clarifies some of my thoughts.

Interesting topic here. Stay safe.
Absolutely right. The colormetric tubes are important, not only because of the price, but because they don't expire half as fast as the sensors in a multi rae. Cranston fire department has the HCN sensors in the Multi Rae, and they dispatch their hazards for air quality measurements at every building fire.
Personally, if 35 ppm is too much for a homeowner to be in the atmosphere, than it's too much for the members of my fire department to be breathing as well. You base 35 ppm on a 8 hour work day, which is all well and good, but what if you have multiple building fires in a short period of time? Overhauling 2 or more building fires in CO levels over 35 ppm with no SCBA can prove to be hazardous to you and your crews health. The CO which attaches to the Hemoglobin doesn't exactly remove itself as soon as you leave the toxic atmosphere, but will only further enhance the level of toxins in the blood streams with the repeated exposures. We al read the same NIOSH reports, and firefighter close call reports, and say that wouldn't happen to us. In our situation, we safeguard ourselves. If keeping your SCBA on for an extra 15 minutes ensures your breathing cleaner air, than so be it. Our jobs as firefighters is hazardous enough without letting our own foolishness blind us into becoming another statistic.
happy holidays and be safe.

(oh and since we all are mentioning our Haz Mat certs, I also am a Haz Mat Technician)
You need to take into account that CO has a half life of 5-7 hours. So it is not leaving your blood stream as fas as you think. Even taking O2 unless you go into a hyperbaric chamber then the time drops dramatically.
The effects of CO can be exasperated by physical exertion, overhaul would definitely qualify.
If you can't get the CO below 35 or can't wait you need to improve your ventilation. Remember most PPVs have a gas engine. They make enough CO to bring a single family home 1500-2000 sq feet to about 60 ppm CO just with fan exhaust. We tested this real world and found a range of 40 - 60 ppm for those sq ft.
As for crew rotation with the 5-7 hour half life you would need to spend way too long in rehab to have a positive effect. Call more help if you are having crew fatigue issues.
You may also want to look into field testing for COHb. Drager makes a cheep and easy system (we use them all the time) and there is a Pulse Ox type on the market as well, draw back with these is price, 3K for unit and maint reserve.
HCN and colormetric tubes is a whole other post. Need to go watch the Packer game!

Lt. Scott Ziegler
North Shore Fire Dept (Milwaukee Co WI)
Special Operations Bureau Hazmat Coordinator
You would be surprised at how many FF's don't think about the fan exhaust.
Most Dept's around us don't or didn't use the tubes until we did our tests.
I know of a few in our area but the "big" city does not.
I think we touched upon the main issue I was thinking about. That was when can we remove our SCBA during overhaul and how do we determine the atmosphere is ok to work in.

I apologize for the delay in responding and moderating but I had 2 deaths in my family before Christmas and then came the holidays but I am back.

Here is a link that looks at the respiratory issues: www.nfpa.org/foundation.
We have recently taken delivery of the scott mask adapters and cartridges. I think if the environment is monitored and declared safe, then the guys can shed the packs and use the adapters. They allow full face protection and repiratory protection for dust during overhaul. We got the P100 cartridges as well as the WMD cartiridges should we ever need to do a mass decon.

What dept are you from?

www.firesmoke.org is all I need to say on this topic. The most comprehensive information you will ever read on "smoke".

Wear your air.



My answers to your questions is YES to all three. Currently we monitor for CO and HCN with action levels of 35ppm and 5 ppm respectively. We do not at this time have a gas monitor for H2S. Yes we have an SOG that references the use of SCBA. SCBA is not required if the levels are below the above action levels. The department began because me being Safety Officer and being a proponent for the 16 life safety initiatives, warranted it. We recently had about a 50% turnover and we are making significant progress instilling it into the newer staff both from an officer side and also from the newbie side. Educate them on the effects of both CO and HCN and they will see the importance.  

Jesse. Training Officer, St Clair Shores, MI.

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