Gas-stove cooking: the fingerprint

Burning natural gas on a residential cooktop is the most-studied indoor combustion source. A burner running for ten minutes produces measurable spikes in NO_x (studies report tens to hundreds of ppb in the kitchen; Terrestream shows this as a rise in the NO_x index, not a ppb value), PM_2.5 (often 50–150 µg/m³ in the kitchen, with brief peaks higher), ultrafine particles, and a tail of combustion VOCs including formaldehyde and acrolein.

RMI and Lebel et al. document the public-health implications: gas cooking is associated with higher childhood asthma risk, and NO₂ in a small, poorly ventilated kitchen can pass outdoor short-term health benchmarks within minutes of cooking. The rise is not subtle; a sensor in the next room usually sees it.

Each cooking method has its own fingerprint. Gas: NO_x rises sharply when the burner lights, then PM_2.5 and VOCs from the food, and humidity from steam. Induction or electric: particles and VOCs from the food alone, with no NO_x rise; the missing NO_x is the tell. Frying: large PM_2.5 peaks from oil aerosol, dominated by small particles and sustained for the whole session. Oven roasting: a slower, VOC-heavy rise over 30 to 90 minutes. Grilling: smoke-like particles with a charred VOC signature. Terrestream recognizes cooking spikes from the combined rise, and the NO_x index shows whether a gas burner was involved.

The most effective single intervention is a properly vented range hood; see the range-hood article. A hood vented outdoors, run on a higher setting and used over the back burners, captures a large share of cooktop emissions; a recirculating hood that filters and returns the air to the kitchen does not remove NO_x at all. The difference shows up in the data as much smaller peaks with the hood on.

Beyond the hood, replacement is the cleanest long-term answer: induction cooktops eliminate combustion emissions while heating food fast and controllably, and after a switch, the NO_x rise during cooking disappears. For renters and others who can't replace the cooktop, run HEPA filtration in adjacent living spaces and open a kitchen window during longer cooking sessions. See gas-to-electric transition.

Note on safety: gas cooking is also a minor carbon-monoxide source under poor combustion (yellow flame tips, sooting). Terrestream does not detect CO; see the CO disambiguation. Every home with a gas appliance should have a CO alarm.