Yes, if the cooking uses gas. A gas hob or oven burns methane to carbon dioxide and water, and a single large burner produces CO₂ at roughly the rate of two or three seated people. A monitor in a kitchen with a gas hob and no hood running will climb several hundred ppm during a meal. Electric and induction cooking produce no CO₂; any rise on those is from the cooks themselves. The CO₂ spike is harmless in itself, but a gas flame also produces nitrogen dioxide and, if it burns badly, carbon monoxide, which is the real reason to run the hood.
Where the CO₂ comes from
Complete combustion of natural gas: CH₄ + 2 O₂ → CO₂ + 2 H₂O. Every kilowatt-hour of gas burned releases about 50 grams of CO₂ and 40 grams of water vapor into the kitchen unless the hood removes it. A typical hob burner is 1.5 to 3 kW; an oven cycles at similar power. Half an hour of cooking on two burners can release 100 grams of CO₂, which in a closed 40 m³ kitchen is enough to raise the concentration by well over 1,000 ppm if none of it leaves.
What a monitor shows
- Gas hob, hood off, door closed: steep rise of several hundred to over a thousand ppm, slow fall afterward.
- Gas hob, hood on: modest rise or none; a good hood captures most of the plume.
- Electric or induction: flat, apart from the cooks’ own breath and steam-related humidity changes.
- Gas oven: a slower, longer rise as the oven cycles for an hour.
The CO₂ curve is a free test of the hood. If it barely changes with the hood running and jumps without it, the hood is doing its job. If the curve looks the same either way, the hood is recirculating through a grease filter rather than venting outside, or the fan is too weak.
Why the spike matters
CO₂ at 1,500 ppm from a gas hob is no more harmful than 1,500 ppm from people. What matters is what comes with it. Gas flames produce nitrogen dioxide, a respiratory irritant, at levels that in unvented kitchens can exceed outdoor air quality guidelines during cooking. A yellow, sooty or unstable flame also produces carbon monoxide, which a CO₂ monitor cannot detect; see CO₂ vs CO. Frying and searing on any hob produce PM2.5; see PM2.5 vs PM10. The CO₂ rise is the visible marker that all of these are accumulating.
Practical steps
- Run the hood on high for the whole cook and ten minutes after, with a window cracked so it has make-up air.
- Use back burners; hoods capture far more from the back than the front.
- If the CO₂ monitor shows no difference with the hood on, check whether it vents outdoors.
- Fit a CO alarm in any kitchen with gas appliances.
- For whole-home monitoring, keep the CO₂ monitor out of the kitchen so meals do not dominate the chart.
Related: why a monitor spikes when people enter and does burning a candle affect indoor air measurements.
Recommended Tools
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Frequently Asked Questions
Does an electric hob raise CO₂?
Not directly. Electric and induction cooking produce no CO₂. Any rise while cooking on electric comes from the people in the kitchen and a closed door.
How much CO₂ does a gas burner produce?
Burning natural gas produces about 0.05 kg of CO₂ per kWh of gas. A 2 kW burner running for 30 minutes releases roughly 50 grams, comparable to what two or three seated people exhale in the same time.
Should a CO₂ monitor be in the kitchen?
It is useful for checking the cooker hood and ventilation, but for whole-home monitoring put it in the living space, where the reading reflects people rather than the stove.
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