Interesting topic.
Few months ago I was flying in a C172 and the ASA sticker detector went from orange to a darker orange then notoriously darker with some black spot. I opened the windows, returned to the airport and canceled the lesson.
I ended up having a strong unusual headache for few days even though I didn’t feel like I was exposed for too long.
Then I started digging more into this and coincidentally the news about CO on the Sala’s flight came in the newspaper.
In the US there is a key chain size detector with a loud warning alarm being sold for about 120 USD and the delivery was not matching my travel dates, so I ended up not buy it.
Basically I am also interested in having my own personal detector that is reliable taking advantage that you started the subject, if any of you can recommend me one, would be appreciated.
Regarding the side effects of tiny exposures, I am also curious.
That day I flew with some detection it didn’t feel bad but it took me few days to associate it with the unusual headache I had after that specific flight.