I once bought an air filter that had the pm 2.5 rating surrounded by a blue/yellow/red halo. The only things it was missing were logging, and the ability to run the sensor without the fan. It could change fan speeds based on PM 2.5, but it was calibrated for a small room, and always ran way too slow.
I wish there were standards around thermostats these days. If there were, then people could sell gizmos that measure PM 2.5, then (if the windows are closed), use it to set the speed of the variable speed blower in central air furnaces accordingly. This would cut our electricity usage by at least 20-30% during fire season.
(I’d love to see a legal mandate for interoperability in this space.)
My furnace blower isn't in use any longer, but it has connections for varying speeds, 6, I think. It only uses 1, though. I'm unsure of how it would even be used in practice, as it appears it's just various voltages. Ideally furnace blowers would be inverter ran so you could just tell the inverter how fast to run the fan, rather than changing the supply voltage.
Mine was a 3.5 ton HVAC, I replaced it with a five head, five and a half ton "mini split"; while the split air has had it's share of issues (like, I got a full refund of the purchase price a few months ago due to manufacturing defects of the copper lines), I prefer having air handling done bear the ceiling and using 20x20x1 inch filters on box fans (or fancy filters if those are your style) on the floor. The mini split has the inverter driven motors everywhere, and is completely silent during normal use.
I have two AQM, and occasionally one or the other will register high CO2 or whatever and I will open a couple of windows and run exhaust fans (built in to the home) to cycle the air, it takes about 20 minutes. The main furnace style system did no filtering or air quality management.
I wish there were standards around thermostats these days. If there were, then people could sell gizmos that measure PM 2.5, then (if the windows are closed), use it to set the speed of the variable speed blower in central air furnaces accordingly. This would cut our electricity usage by at least 20-30% during fire season.
(I’d love to see a legal mandate for interoperability in this space.)