CO Turn Cyanide Turn False?

On Tuesday, March 8^th, 2011, my fire department was toned out for a CO without illness call in our district at 0724 hrs. 

Chief gets on scene and establishes command.  I was on the first-due engine with a driver, a firefighter and me as officer.  I advised the firefighter to turn on the multi-gas meter while responding non-emergency. 

As I call arriving, my chief advised me to check with the homeowner and investigate.  I took the gas meter (which is capable of detecting Cyanide (HCN) and Carbon Monoxide (CO) ) from the firefighter and my chief gave his single gas Carbon Monoxide meter to the firefighter so we had two meters going in. 

I met with the homeowner, who was waiting outside and had his family and the pet hamster in the car, due to the cold weather.  I asked the homeowner if he had his vehicle running in the garage and his answered no to the question.  Then he went on telling me that he has five CO detectors in his house that went off intermittent throughout yesterday afternoon and overnight and into this morning.  At one point, he did take all the batteries out of the detectors to silent them and then he notified the fire department. 

After receiving some of that information, I motioned the firefighter to follow me and investigate by going through the attached garage entrance and into the house.  Both of us had full PPE and SCBA but had our masks dangling and didn’t have our air on due to the nature of the call.  I led the way into the house with the firefighter following behind me.  I opened the door leading into the house from the garage and took two or three steps into a small hallway when my gas meter started to alert.  I looked down at the screen and noticed that Carbon Monoxide was at 8 ppm but Cyanide was at 50 ppm and counting even higher. 

We backed out into fresh air.  I ran the gas meter in fresh air to zero out the sensors.  We went back in and still got high readings of Cyanide in the same area as before.  Again, we backed out and talked to the chief face to face to let him know that we were getting high readings of Cyanide and barely getting Carbon Monoxide.  Chief advised the fire investigator, who was still responding.  I advised chief that the firefighter and I will be going on air and continue with the investigation inside the house. 

On air now, both the firefighter and I continued back into the house with our gas meters at the ready.  Again, my gas meter read 70 to 85 ppm for Cyanide and 24 ppm for Carbon Monoxide and the other gas meter was reading 24 to 28 ppm for Carbon Monoxide.  This was consistent on the first and second floor of the residence.  We continued our investigation by going down the staircase leading to the basement.  While walking down the stairs, my gas meter had Cyanide exploding off the chart by having the screen read “+++”.  Carbon Monoxide was holding at 28 ppm.  Even checked around the furnace and hot water tank, which the firefighter was getting 28 ppm for Carbon Monoxide on his gas meter.  I advised chief on our investigation over the portable radio and pulled back out. 

I advised the fire investigator to not enter due to the high levels of Cyanide and at one point the firefighter felt light headed due to being exposed the first time.  Met with the homeowner and started questioning him on any other factors that could be letting off Cyanide.  He made mention of the natural gas fed fireplace and his hot water tank leaked last Tuesday.  After the hot water tank leaked, he called in a company to cut and remove parts of the damp carpet and let electrical dehumidifiers to help dry up the basement on Wednesday.  On Thursday, the homeowner installed the new hot water tank himself and powered it on Friday.  The fire investigator and a representative from the utility company started to think that the Cyanide could be coming from “fake embers” used for natural gas fed fireplaces or the damp carpet and synthetic matting could be giving off Cyanide.  The cleaning company didn’t use any chemicals and that there could be false readings messing up the sensors. 

At this time, we had a second multi-gas meter with a Cyanide sensor to assist in verifying my gas meter.  Again, Cyanide was still present and both multi-gas meters were showing high readings of Cyanide and low readings for Carbon Monoxide.  Ventilation was performed to lower the levels to a safe atmosphere for the fire investigator and the utility representative inside.  Both of them has gas meters, which were multi-gas but didn’t have any Cyanide sensors.  They checked the fireplace and hot water tank and furnace to check for any leaks and see if they could recreate the levels of Cyanide and Carbon Monoxide. 

The fireplace was tagged out of service due to a small leak by the utility company.  Unfortunately, the fireplace wasn’t the correct source of the Cyanide.  The highest the levels returned to were 0 to 5 ppm for Carbon Monoxide and 28 ppm for Cyanide in the basement. 

After two hours being on scene, chief decided to turn the house back over to the homeowner and advised the homeowner that we’ll be back later in the evening to check if everything was okay for the homeowner and family. 

Later on that evening, the chief and I went back to the scene and checked the readings with our multi-gas meter and single gas meter.  CO was barely 5 ppm and Cyanide was at around 49 to 50 ppm.  Though, the family looked well and didn’t exhibit any symptoms of Cyanide or CO poisoning and did have their batteries back into their CO detectors again.  Even the family’s hamster was alive and well. 

This just goes to show you that you have to think outside the box and explore every parameter before declaring the scene safe for the people.  Remember that the gas meter is a tool but a valuable tool in the fire service, which shouldn’t be taken for granted.