Breath Carbon monoxide levels high for non smoker- lactose intolerance?

[Babycat21]

Hello

Has anyone had their carbon monoxide tested (via breath) during their routine antenatal appointments and the result be unexpectedly high?
I don’t smoke, no smokers in the house, no carbon monoxide leaks (checked with two sensitive monitors), car is fine nor any other environmental factors identified.
It was suggested that being lactose intolerant could cause a high carbon monoxide test result but I have never really noticed any problems with consuming lactose. I’m not sure what would be the possible effects if my carbon monoxide level remained high due to lactose.
Could it be anything else?

Has anyone else had this? What was the result?
I’m struggling to get much info on this topic.
Thank you

I had this. But I worked and lived in a fairly large city and commuted by bus everyday. I was told by the nurse that despite being high for a non smoker it was also normal for that area and nothing else happened.