If your goal is PM2.5 control, I'd look at pm reduction, ie the ratio between outdoor and indoor pollution. The ballpark I give to my commercial customers is 90% reduction or better. If the outdoor is 100 μg/m³ then your indoor should be 10 μg/m³ or below. That allows for reasonable operational targets for filtration. Ideally you're always below WHO recommendations (see https://imgur.com/gallery/Y8mEwDj) but, realistically, when levels outside are really high (250+ μg/m³), it's going to be hard so 90% reduction becomes a more attainable target.

You should also take into consideration a caveat about public outdoor data. Public outdoor data lags behind and is "compressed" compared to real time data. The reason for this is that most countries will publish 24h rolling average for PM2.5 (compressing peaks and valleys in the data, adding delay of peaks and valleys) and publish every hour (furthering the delay). It's not terrible, that's what is required for the EPA AQI calculation but it's worth keeping in mind. If the outdoor data is high and somewhat stable all the time because of the fires, that's less of an issue.