High co2 reading, non smoker, house has been checked

[August21yellowbaby]

I had a reading of 7 at the hospital yesterday
I was told by consultant that I needed to get the boiler checked at home which I did straight away by plumber
Boiler fine
Non smoker
I was only in the car for 5 minutes maximum on the way to the hospital yesterday morning, hardly any traffic
What else could cause this ?

https://assets.publishing.service.gov.uk/media/5a80a87840f0b62302694c5f/CO_antenatal_checks_algorithm_2015.pdfV

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My CO reading went from 1 at my first midwife appointment to 4 or 5 at my second which was at a different hospital in a more built up area. The midwife said that it can be pollution in the air from other cars/car parks as well. Have you had your car checked for emissions? Even 5 min exposure would likely be enough to increase it a bit (given smoking one cigarette can increase it and they only last a couple mins!)

CO2 or CO?...there's a big difference

I had high readings and then I moved home and mine went down to 1. When I had the high readings, I lived in a flat and below there were smokers and we could often smell their smoke coming up through the walls so I’m sure that caused the high readings. If you live near smokers or regularly come into contact with them, it could be that.

Sorry I think it's co, the machine you blow into at every appointment?

check your car, I believe you can get little portable carbon monoxide is it readers? they can go in your car, mines normally 1 on the reading but since walking to hospital for appointments when they take them the reading is 2 or 3 as its on a very busy main road

Agree get a carbon monoxide monitor. (battery one) take it in your car and with you around the house.
I think you can get it from a gas hob too?

Do you burn candles at home? I was having unexplained high readings when I was pregnant. Boiler checked, car checked, couldn't find any other causes. Ended up borrowing the doctors meter for a couple of days (long story) and the only link we could find is when we'd be burning candles at home.

I had very high readings at one appointment and it was due to me painting the shed the day before!

Log burner at home with insufficient ventilation.

Do you have a wood burning stove?

I had this at a recent midwife appt. Non smoker, electric car, no sources of CO2 in house, should have been really low. Midwife was pressing me asking if I was a secret smoker. I said that’s odd and could DH have a go, his was high too. I asked when the breath test machine was last calibrated, midwife could not say. I asked to use another machine. We did and reading went down to 1. It was the machine as it hadn’t been calibrated!