PM2.5 from cooking: how to see and reduce indoor pollution

PM2.5 particles are small enough (under 2.5 µm) to reach deep into the lungs and enter the bloodstream. The WHO 2021 guidelines recommend 24-hour PM2.5 below 15 µg/m³; a typical evening of frying on a gas hob can briefly push a kitchen into the 200–400 µg/m³ range and leave the rest of the house elevated for hours.

The outdoor air people worry about is rarely the indoor air that does most of the damage. Cooking is.

Below 12 µg/m³: typical clean indoor air, often cleaner than outdoor.

12–35 µg/m³: elevated. Common during low-intensity cooking, candles or evening with windows shut.

35–150 µg/m³: high. A clear cooking event, often with PM peaks lasting 30–60 minutes.

150–500 µg/m³: very high. Aggressive frying, grilling, or kitchen with poor extraction.

Above 500 µg/m³: unsafe sustained. Open windows, switch off the hob, or leave the room until levels drop.

Three things matter most: (1) run the extractor hood from before you start cooking until 10 minutes after; (2) close the kitchen door to other rooms so the plume does not migrate; (3) crack a window during high-PM cooking — even a small one materially improves clearance.

Switching from gas to induction reduces PM2.5 by 30–70% in most kitchens. An air purifier in the kitchen helps remove the plume after the event but does not replace the extractor — extraction takes the pollution out of the house, purification just circulates it through a filter.

Envora One uses a laser scattering PM sensor that resolves PM1, PM2.5 and PM10 separately, sampled minute-by-minute. The dashboard shows the plume rising in real time as you cook and the curve falling as ventilation clears it — which makes it obvious whether your extractor is doing its job.

Pair with the VOC guide for the chemistry side, and buy Envora One if you want to see your kitchen air as it actually behaves.