A lot of it is from the natural gas combustion, but the food itself also contributes. The day I got an air quality sensor (to assess risk from wildfire smoke), I realized that my kitchen is basically an asthma factory for the kids. (I haven't actually assessed the risk from that, as its different from wildfires smoke, but j just keep the kids out of the kitchen now until the air clears)
I have some air filters with air quality sensors on them, and we have an electric range so there's no natural gas combustion happening. Often when cooking (pan frying especially), those sensors will max out and send the air filters into turbo mode for a good while.
Yes, hot oils trigger the formaldehyde sensor every time for me. For doing wok frying, I got an outdoor propane burner so that it's far more dilute, and that delicious cancer-causing wok hei is delivered only to our stomachs rather than lungs and stomachs. The outdoor wok burner is also far superior to any indoor residential gas stove too for this purpose.
The actors at Conner Prairie, an 1836 "living museum" in central Indiana, explain that some of the nicer houses have a separate out-building just for cooking, to keep the heat away from the main living space, and reduce the risk of burning down the whole house too. Maybe we'll move back to that design, to keep the pollution in the main space down.
