PM 2.5 particles are the smallest particles and are in the air inside and outside of our homes whether we have a stove or not (think the finest of dust particles).
A wood burning stove, correctly working, will not exceed small particle safe-guidelines (see foot of this article for Julian's "in the room" analysis) or come anywhere close.
The conclusions of a US survey in 2019 by the Journal of Exposure Science and Environmental Epidemiology were that homes without stoves had a Median PM 2.5 of 6.65 µg/m3whilst homes with stoves were a fraction higher at 7.98 µg/m3(and these were not the latest Ecodesign stoves). This fairly reflects my own tests (although with a chimney liner and Ecodesign stove my PM2.5 increases compared to an unheated home were even smaller) and appears to reflect other studies I have seen.
Just think about that for a minute: a home has a natural and normal amount of 6.65 µg/m3 PM 2.5 particles all of the time, 24 hours a day. Using a wood stove can increase that a smidgen for the few hours the stove is on (whilst still remaining well within recommended safe guidelines). So "very safe" becomes "still very safe". A car tyre with 20% less tread is more dangerous than a car with a brand new tyre but this does not mean the car should be banned or carry a health warning: the car falls within safe levels or it does not.
With regard to clean air DEFRA states that their cleanest and freshest air classed is anything under 11 µg/m3. The World Health Organisation's advice is not to exceed annual average concentrations of PM 2.5 of 10 µg/m3n. Note that this is an average over a whole year so even if your stove was running 24 hours a day, 365 days a year the average PM 2.5 levels would still be within WHO safe guidelines. For most homes, woodburners are only used for a few hours a day, a few months of the year.
My stove, in my house, provides a great deal of warmth and pleasure. I am very happy to state it is very safe and our air is clean.
There are, and always have been, a few, very vocal, killjoys that have it in for "trendy woodburners".
"Get over yourselves".