I've seen plenty of articles about gas stoves and the impact on indoor air quality. Specifically, there are reports of much higher CO2, NOx, PM 2.5 particulates, and formaldehyde, relative to electric stoves. However, I can't find any reference specifically to natural gas vs. propane. It looks as if most such articles are written with natural gas in mind.
How do natural gas and propane stoves compare in terms of indoor air quality.
Propane is a hydrocarbon that ideally consists of length-3 carbon chains (C3H8 also known as C3). However, cooking propane is never 100% pure, and contamination from soluble hydrocarbons from C10 up to C40 is likely.
Natural gas is a mix of hydrocarbons primarily composed of methane (CH4) but also longer hydrocarbons and alkanes. In Canada, natural gas must be at least 90% methane to be legal for sale. Some common impurities in natural gas are sulfur compounds and mercury.
Under idealized circumstances (100% pure methane or propane and 100% complete burn) the only combustion products are heat, water, and CO2. However, ideal circumstances are never achieved in the real world.
This study shows that normal combustion of propane is likely to produce carbon monoxide (CO) because of less-than-perfect combustion efficiency and particulate matter (PM2.5) because of impurities and contaminants.
There is no substantial safety difference between propane and natural gas when used for indoor cooking. I strongly recommend electric (either resistance or induction) heat for safe indoor cooking.
The article you say confirms that propane produces the same toxicity and off-gassing as natural gas does not appear to be research related to cooking ranges. The article refers to "jet pools" of ignited materials, and done outdoor with burners that are not designed or operated for maximum burn efficiency, as range burners are. A simple Google search indicated that natural gas is classified "low toxicity" while propane is "non-toxic". I'm not sure why you feel the need to discredit propane as a cooking fuel, but in point of fact, it appears to be substantially less polluting tha n. gas. You also mention that propane suppliers rarely sell a 100% clean product, which can cause pollutants, but you include no data to substantiate that claim, such as measurements taken in different parts of the country from different suppliers.
If a burner is working properly both gases should only produce CO2 and water ( and the original nitrogen from air). The mercaptan orderant produces minuscule SO2. The BTU level of nat gas is generally adjusted by adding air.
