A purifier helped — but the cheaper fix comes first
Summary: Year-long study, 67 gas-cooking homes. HEPA+carbon purifiers cut indoor NO₂ ~36% (20→13 ppb); PM2.5 fell too.Data source: MDPI (2025)Why it’s a problem? Gas hobs are everywhere in UK kitchens, and correlates with “is my house making me sick”
Hi, Chris here. Since starting my journey with testing and delving into the world of measuring indoor air quality, the sheer number of things that need to be tested, or that should be tested has blown my mind. I knew that it would be a rabbit hole, but not to quite this extent. I had no idea about the relationship between gas hobs (which are still very common here in the UK) and NO₂.
The take home here is turn your fans on well before you start cooking on a gas stove, so I presume the air is already flowing before allowing the build up of the pollutants… and then start the purifier when you’re done to ‘clear up the remaining’.
What the research is telling us:
If you cook on gas, your kitchen air carries something you’ll never see or smell: nitrogen dioxide, a gas that irritates airways and can worsen asthma — and children and older relatives feel it most. A new year-long study put air purifiers into 67 gas-cooking homes, and the results are worth a look.
After the purifiers went in, indoor nitrogen dioxide dropped by roughly 36%, falling from about 20 to 13 ppb, with fine-particle pollution (PM2.5) reduced as well. That’s a real cut in a pollutant tied to coughing, headaches and tighter breathing. MDPI
But here’s the part the headline skips: the purifier cleaned up after the NO₂ was already in the air — it didn’t stop it being made.
So the smartest approach is layered, cheapest move first: extractor fan on before you light the hob, a window cracked open while you cook, and then a purifier to mop up what’s left.
It also makes the case for actually measuring your air. You can’t smell NO₂ and you can’t manage what you can’t see — a monitor turns an invisible problem into a number you can act on.
Key topics: Nitrogen dioxide (NO2); Particulate matter (PM); HEPA/carbon filters; Gas stoves