How Much CO is too much?

[mike]

I have a high-sensitivity CO detector. Been reading 000 for years. All of a sudden tonight, it went off at 15PPM. House has been closed up tight all day.

I replaced the battery and moved it to another room. Reading gradually went back to zero. Furnace is off, but I turned off the gas anyway. Don't have anything else that burns fuel.

So, I opened the windows, turned on the exhaust fan and the reading went up. So, took it outside and it reads 28PPM. There's a light breeze, so any local source oughta dissipate??

I can't think of a detector failure mode that would explain the readings. I have two other standard-sensitivity CO detectors that remain silent.

So, is 28PPM high for an outdoor reading? Can't think of anything I could do about it anyway.

[bob haller]

IS THERE A FIRE IN YOUR AREA?

[Frank]

From a Matheson Gas MSDS:

EXPOSURE LIMITS: CARBON MONOXIDE:

50 ppm (55 mg/m3) OSHA TWA 35 ppm (40 mg/m3) OSHA TWA (vacated by 58 FR 35338, June 30, 1993) 200 ppm (229 mg/m3) OSHA ceiling (vacated by 58 FR 35338, June 30, 1993) 25 ppm ACGIH TWA 35 ppm (40 mg/m3) NIOSH recommended TWA 10 hour(s)

These are worker limits. Most companies would probably comply with the lowest limits but OSHA would be the law.

Maybe your detector is off or maybe you live in a high traffic area.

[Han]

mike wrote in news:jot8t2$7g9$ [e-mail]:

How old is the detector? Some are done after 2 years. According to wikipedia: When carbon monoxide detectors were introduced into the market, they had a limited lifespan of 2 years. However technology developments have increased this and many now advertise up to 7 years.[8] Newer models are designed to signal a need to be replaced after that time-span although there are many instances of detectors operating far beyond this point.

[Caesar Romano]

On Tue, 15 May 2012 02:50:22 -0700, mike wrote Re How Much CO is too much?:

It looks like you have a CO source upwind of you. Bad news.

I wonder what it would read at ground level in Hong Kong?

[trader4]

Given that he has two other detectors that are silent and the symptoms I would expect that it's a faulty detector.

He could check with that guy Holmes on TV. He seems to have a fetish for CO. Every garage he goes into he immediately declares it's not sealed sufficiently from the rest of the house and how everyone is gonna die. He says your car is gonna gas the whole place with CO and kill the kids. Seems much overdone to me. I don't know about Holmes, but my car only runs with the garage door wide open, the exhaust right at the door pointed out, and for 15 secs or so.

And as someone else pointed out in another post a while back, how much CO does a typical modern car give off? With the catalytic converters and EPA mandates, I would expect it's a small fraction of what it was 40 years ago. Now, if you close the garage door and run the car, that's another story.

[Steve Barker]

if it's over 5 years old it needs to be 86'd and replaced. The manufacturer may send you a new one. They did me.

[Steve Barker]

once the modern vehicle is warmed up and the cat is "lit" off, you probably couldn't get a reading out of a co detector even with the door closed. You'll die from lack of o2 before dying of co. Now, a lawnmower.... that's a different story. We could set off the co detector in the shop i worked at in a matter of 2 minutes running a lawnmower. Sometimes with the door open even.

[HeyBub]

Which brings to mind the question: How do you test a CO detector?

Testing a smoke detector is easy - I take it into the kitchen when the wife is preparing supper, but a CO detector?

[Fat-Dumb and Happy]

I put a cigarette below it, 250 ppm isn't unusual when you do this and the alarm will go off.

[Robert Macy]

It is my understanding that the main problem with CO is that it PERMANENTLY bonds to the iron/hemoglobin, or such. Which translates to removing those cells from carrying any oxygen. Which means post- exposure can kill you. Takes time for the body to replace and get the oxygenation system back up and running again. Heart patients are REALLY sensitive.

[chaniarts]

no, it's not permanent, but it is a much longer timer than co2 for it to come out of the bonds.

[HeyBub]

That's a great idea. Thanks.

[Mark Lloyd]

[snip]

IIRC, "permanently" is 2-3 months, the lifetime of a red blood cell.

[Robert Macy]

I preferenced my statement with "It is my understanding..." to indicate that the statement was based upon memory and not citable scientific/medical literature. Actually based upon undergraduate experience in a COLD climate and listening to the gossip after some dating couple had succumbed to CO poisoning from an idling engine as the couple said goodbyes [no pun intended] while inside a warm car.

From your reference: "The goal of treatment for carbon monoxide poisoning is to remove carbon monoxide from the hemoglobin in your blood and bring the oxygen level in your blood back to normal." Evidently in the presence of 'pure' oxygen, the hemoglobin - CO bond can be broken.

The article did go on to say that hyperbaric pressure treatment was sometimes necessary.

All much safer than whole blood transfusions. But, I bet they work.

[micky]

I once bought a bag of CO. It was made to test CO detectors.

It was something like a single-serving ketchup bag. I bought it at a hamfest and it was sort of beat up and probably old, but it still had a bunch of gas in it.

He either had only one bag, or under ten.

I haven't seen it lately. I think I used it and it worked.

This is mistakenly titled C02, but the listing and the label on the bottle says its CO gas:

bottles (or maybe cans) for 210 dollars. It doesn't say how big the bottles are or indicate how many tests you can make with one.

20 years ago, I asked the customer service person if I could just move my CO detector to the furnace room, where i figured it would find some, and she said that would be bad for it if the CO level was really high.

I just light a kitchen match, a wooden one 2 inches long, and hold it under the smoke detector. The one wired to the house still works after 33 years**.. And it also went off recently when I overheated a skillet with oil in it.

**( have newer battery operated ones too.

[Peter]

Relative safety depends on the severity of the CO poisoning and the presence or absence of other medical problems. Patients with emphysema or other significant lung abnormalities, or with "holes" in their hearts (septal defects) are not good candidates for hyperbaric oxygen; massive transfusion might be safer. In the absence of significant cardiac or pulmonary pathology, hyperbaric treatment is much faster, easier, cheaper, and safer than massive transfusion.

[Earl]

You'll know when it kills you.

[mike]

Isn't this a simple diffusion problem?

Hemoglobin is continuously releasing whatever it has and reattaching to whatever is in the vicinity. The relative concentrations and bond strengths determine the statistics of the process. If the CO bond is stronger and the half-life of releasing it is higher, most of the available hemoglobin molecules would have previously attached to CO2 or O2. If the air concentration of CO is high, the probability of re-attaching to a CO molecule is higher.

If the "half-lives" of the bonds are significantly different and there's any available CO in the air, things can go very wrong very fast.

Oxygen therapy insures that any CO that is given up is not likely to reattach to another hemoglobin and pushes the statistics the other way.