Persistent kitchen smell is produced by grease deposits on surfaces and in ventilation ducts — they carry on releasing smell long after the cooking is done.
When you cook, hot oil and fat partly pass into the air as a very fine aerosol. These particles are so small that an extractor hood only catches part of them; the rest travel with the flow of warm air and settle on every surface in the room — on the tops of cupboards, ceilings, walls, curtains and soft furniture, not just near the hob.
Then the main thing happens: the settled grease oxidises. In contact with oxygen in the air it breaks down, forming compounds with that characteristic rancid, acrid smell. It is the same process that makes old oil in a bottle unusable. So the smell comes not from the food you cooked yesterday, but from the layer of grease that has built up over years.
This also explains why the smell gets stronger over time rather than fading. The older the layer, the more oxidation products there are, and the warmer the room, the faster they are released into the air.
What smells is not the food, but a layer of grease that has built up and oxidised over years.
If you have washed the kitchen and the smell has stayed, one of those four has almost always been missed. A simple test: run a finger along the top of a cupboard or the edge of the ventilation grille. If your finger comes away sticky rather than dusty, that is a grease layer and it has to be removed with a degreasing agent.
Two further places practically everyone misses: the gap between the hob and the adjacent unit, where oil has been running for years and which is never opened, and the back of the oven with its ventilation openings. Material builds up in both and smells constantly, not just while you are cooking.
In restaurants and cafes the scale is different but the mechanism is the same: the critical points are the extraction ductwork and the grease traps. The layer builds up much faster there, and it affects not only the smell but also the extraction capacity.
If you can smell food you are not cooking, it almost always arrives through the shared ventilation shaft. In a block of flats the kitchens share a riser, and in a properly working system air from all the flats travels in one direction — up and out through the roof.
The problem starts when the flow reverses somewhere. The commonest reason is a powerful extractor hood that somebody has connected directly into the shared duct: it pushes more air into the shaft than the shaft can carry away, and the resulting overpressure looks for a way out through the neighbours' grilles. The second reason is sealed windows with no air inlet: your flat becomes a lower-pressure zone and air is drawn into it from the shaft.
Hold a thin sheet of paper against the kitchen ventilation grille with a window slightly open. If the sheet stays put, the duct is drawing. If it falls away, the draught is weak or reversed.
In that case ozone treatment will remove the smell that has already soaked into your flat, but it will not stop it arriving. The long-term answer is a ventilation question that has to be dealt with at property-manager level, because the riser is common property. We say so honestly rather than selling repeat treatments. More on the Air disinfection page.
People often wonder why kitchen smell is in the bed linen and the wardrobe when the door was shut. The reason is that grease aerosol travels with the air, and the air in a flat never stands still.
If the kitchen is open to the living area — standard both in new builds and in reconfigured Soviet-era flats — there is no barrier at all. If the extraction is not working well enough, the warm air with its vapours goes through the whole flat and settles where the surfaces are cooler and the materials porous: on curtains, the bed, the sofa, clothes in the wardrobe.
That is exactly why, with kitchen smells, textiles matter as much as surfaces. Ozone treatment handles that part well — but only after the grease layer in the kitchen has been removed, because otherwise the same process starts again the following week.
We check the hood, the filters and the places where grease deposits have built up.
We clean the grease layer off the surfaces — that is the source of the smell.
We treat the grilles and the accessible part of the duct.
We treat the room, the textiles and the soft furniture.
We tell you how often the filters need cleaning so the problem does not return.
One more honest note about recirculating hoods. If a hood is not connected to a duct and only filters the air, it never removes the vapours from the room — the grease settles right there. Build-up is faster in a kitchen like that, and cleaning has to be more frequent.
Ozone treatment €1.20/m², minimum €60. For catering businesses we set the scope and price after an inspection — see Restaurant and cafe disinfection.
If you cook a lot — roughly once a month. A saturated filter not only gives off smell but also significantly reduces the hood's capacity.
Grease aerosol and smell spread through the whole flat, especially if the kitchen is open to the living area or the extraction is not working well enough.
Yes. In catering businesses this is usually a broader job that includes the extraction system — we set the scope after an inspection.
Describe the situation — we will tell you whether treatment is needed at all, and which one.
Fill in the form — we will call you on the number you provide, ask a few clarifying questions and propose a solution.
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