Ahem... I do not know how much USA average family cook but... Typically a home is not sealed: an old one without a VMC typically leak air from multiple places a

Ahem... I do not know how much USA average family cook but... Typically a home is not sealed: an old one without a VMC typically leak air from multiple places and both have people coming and going without Star Trek teleport so opening and shutting doors... That's to say even poor ventilated environment with normal gas cooking do not saturate enough the air of CO₂ and water to cause any symptom... Small gas stove to heat maybe it's different, but cooking...