In the precautionary statements, states 0.19% is flammable, so guessing that may be the actual percentage of CO in it.
So 0.19% would be 1900ppm, which should be enough to set an alarm off, but shouldn't otherwise be that dangerous as you're not breathing the pure contents of the can, which is small in comparison to room volume.
(Also, if you were, the lack of oxygen would get you first!)
@foone
I wonder what CO sensor manufacturers say? Local fire department told me a decade ago that CO sensors lose sensitivity to the gas by exposure. Putting one by a vehicle exhaust pipe to see if it worked was a bad idea & meant that a replacement was needed.
@michaelgemar I'm not good at chemistry type stuff but it depends how big a space it is. The recommended level is under 9 or 25 ppm, so it gets dangerous fast. 200ppm+ means you start getting headaches and nausea after an hour or two, 3000ppm means you've got mere minutes before headaches, 10-15 minutes before you're dead.
@foone@michaelgemar The company website shows using the canister with a cup-like device to test the sensor. I’m guessing the canister is something like 300 ppm, strong enough to trigger the alarm even when mixed 50/50 with ambient air, but weak enough to not be a hazard unless you start deliberately abuse it.
@NireBryce yeah! it's implied that this contains CO, sure, but I had to check the rest of the page to confirm that this is really just CO, not some chemical that the sensors are also sensitive too