What is the best way to test for carbon monoxide in a home?

5 Best Carbon Monoxide Detectors - Jan. 2018 - BestReviews

For inspecting I carry this one, it has a readout that tells you the level, alarm goes at 35 ppm
Extech CO10 Carbon Monoxide (CO) Meter, 1000ppm

On the subject of CO, I find that even modern gas ovens in good condition emit some CO, particularly right after they are fired up. Can anyone suggest a reasonable test method and PPM range for testing gas ovens?

parakeet ?

OSHA standards for people in the workplace is maximum 50 PPM CO for 8 hours.
For inside a home that is excessive, call a service guy right away.
A properly adjusted and vented natural gas appliance should not produce ANY CO.
If you are using a tester any reading over 25 is cause for concern IF you are getting that reading, say 5 feet or more away from the appliance.
If you are going to stick your tester inside ovens or up chimneys I would be concerned if you got consistent CO readings higher than 30 PPM. But you should not be doing that. Test where a person would normally be in relation to the appliance, and wait for a bit to see if the reading is consistent. Compare inside and outside readings.
A small burp of CO when starting up should not be anything to concern yourself about so long as it settles down to near nothing shortly after.
There may be a small amount of CO in the natural gas as shipped. In the old days CO was called coal gas, and was used for lighting and ovens. That is where those old jokes about sticking your head in the oven and almost instantly dying come from, it was not a joke when household gas was mostly CO.

The CO from a range/oven is a concern about the ventilation system not the appliance.

Hope your testing it correctly.

I see this on all gas ovens. They put out dangerous levels of CO while they are in the ‘preheat’ mode. I always test for CO through the preheat cycle and until it reaches set temperature. If there is still CO at the set temperature, I report it.

Also, I always run the vent fan, if it’s above the stove, while doing this to reduce the concentration of CO!