CO2 is not a problem in cooking combustion quantities AND is significantly denser (so "heavier") than air.
As fyrepenguin said
"At STP, air is 1.29 g/L, while CO is 1.25 g/L.".
Molecular weights per gram mol are
CO 28 grams
O2 32 grams
N2 28 grams
O2:N2 at 1:4 ratio 29.2 g.
I'd expect CO to JUST rise - but with open sides and even a modest ...
The answer to this is a resounding: No.
The main problem with suffocation and cookers is in enclosed spaces where there is no airflow. Suffocation when using a cooker can happen when either the O2 concentration drops below the minimum needed, or when the CO2 (carbon dioxide) or CO (carbon monoxide) concentration rises to a toxic point. In the case of ...
I assume by "gas" you mean the exhaust from your stove? Carbon monoxide? If you're using isobutane (typical US backpacking stove fuel) CO is not normally a significant emission. Even if it were, you'd have to be cooking in a pit or an enclosed space for it to accumulate as CO is heavier than air. (It has been pointed out to me the CO is in fact lighter than ...