Fire Engineering Training Community

Where firefighters come to talk training

Hey all, I was just wondering if anyone had any data on carbon monoxide.  In particular, at what level of CO present should a firefighther have an SCBA on?  We have always used that if it is less than 35 PPM then no SCBA needs to be used.  I have recently seen that "Acceptable Atmospheric Conditions" are Less than 30 PPM.  What do you use as a basis and where did you get the information to support?  Thank you for your comments.


Views: 878

Reply to This

Replies to This Discussion



There is a great deal of new information out there.......If you go to the link below you will find OSHA and NIOSH guidelines


This is cut and pasted from the website below.......PLEASE CHECK TO SEE IF THERE IS NEWER INFO AVAILABLE BUT THESE ARE STILL VALID.




The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for carbon monoxide is 50 parts per million (ppm) parts of air (55 milligrams per cubic meter (mg/m(3))) as an 8-hour time-weighted average (TWA) concentration [29 CFR Table Z-1].


The National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit (REL) for carbon monoxide of 35 ppm (40 mg/m(3)) as an 8-hour TWA and 200 ppm (229 mg/m(3)) as a ceiling [NIOSH 1992].


The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned carbon monoxide a threshold limit value (TLV) of 25 ppm (29 mg/m(3)) as a TWA for a normal 8-hour workday and a 40-hour workweek [ACGIH 1994, p. 15].

* Rationale for Limits

The NIOSH limit is based on the risk of cardiovascular effects [NIOSH

The ACGIH limit is based on the risk of elevated carboxyhemoglobin levels [ACGIH 1991, p. 229].


Be safe! When in doubt wear your SCBA.....A very good resource for HCN and CO  ..........go to Peoples Burn Foundation and they have training videos that are first class with the latest information....... REMEMBER  TO READ ABOUT HCN SINCE THERE IS NEWER INFORMATION STATING HCN IS NOW CONSIDERED MORE DEADLY THAN CO.....AND THE TWO COMBINED ARE VERY SERIOUS ISSUES........AND WE KNOW THEY ARE BOTH PRESENT AT EVERY FIRE.



     Danny gave all the technical info. So I will just give you my opinion. Why would you want to breathe anything other than AIR? We have SCBA's so why not use them, the more we use them the more comfortable we get with them, its like training.

I know SCBA's can be hot and fog up and all the other excuses we have for not wearing them, however why not err on the side of safety.

Others in the department may disagree and say not to worry its just a routine call, that never happens here, it always happens to the other guy..... well to me, you are the other guy, so please err on the side of safety and wear your SCBA if in doubt. Don't make me call your mom!


is your question; during overhaul, when should your crews to be on air?  The answer to that should be, ALWAYS.  The stuff that is killing you after a fire is not CO,  it's nano particles, hydrogen cyanide, acrolein, phosgene and a bunch of other cancer causers, blood agents and asphyxiants.  None of these are going to set off a basic 4 gas monitor, so assume that bad stuff is present and stay safe.

The "Consumer Product Safety Commision" published a guide for responding to residential CO alarms. It was created for the First responder and is quite informative.
I have attached the link. you will find the document was published in 02 however the information is still relevant today. Everyone else here has also given some spot on info as well! 

-Eric, we use the same numbers you mentioned, 35 PPM, this level is in accordance with OSHA. Anything below this is generally regarded as safe. Remember that the amount of time exposed also factors specifically into the established exposure equation. 

-Not sure I agree with Larry as "always" is impractical and unnecessary when one considers that there are technically "unsafe" levels in your home when cooking supper with the windows closed.

Reply to Discussion


Policy Page


The login above DOES NOT provide access to Fire Engineering magazine archives. Please go here for our archives.


Our contributors' posts are not vetted by the Fire Engineering technical board, and reflect the views and opinions of the individual authors. Anyone is welcome to participate.

For vetted content, please go to

We are excited to have you participate in our discussions and interactive forums. Before you begin posting, please take a moment to read our community policy page.  

Be Alert for Spam
We actively monitor the community for spam, however some does slip through. Please use common sense and caution when clicking links. If you suspect you've been hit by spam, e-mail

FE Podcasts

Check out the most recent episode and schedule of

© 2024   Created by fireeng.   Powered by

Badges  |  Report an Issue  |  Terms of Service