This was in the news last month and might be referring to the same source
reply'Replacing gas stove can help asthmatics as much as some drugs, US experts find'
https://www.theguardian.com/environment/2026/jul/24/replacin...
Germany has a ton of NO2 for other reasons, for example diesel motors
reply> N02 is a very hazardous air pollutant which doesn’t get a ton of attention. The main sources are combustion engines and gas stoves. Asthma looks to be mostly caused by gas stoves
replyThat makes sense but the unverified claim is that gas stoves are the main contributors to asthma.