Can anyone advise on whether it would be a good idea to get an air purifier?
I bought one with a HEPA filter about six months ago as I'd developed some sort of persistent sinusitis. Where I am is near a medium-sized, main road but it's on a hill so cars and trucks brake to stop at the lights outside. It took me years to realize that the dust is probably from the brake linings. I don't know how toxic that is but it should be kept in mind. But the PM 2.5 particles from deisel and petrol exhaust are, of course, what you want to keep down. The PM 2.5 can get into your brain, it's now been discovered, doing god-knows-what damage.
But the filters do work. I got a Devanti (a Chinese brand) as it was pretty cheap, online, and it does have a meter to show how much of the PM 2.5 is in the air. I don't know how accurate it is but it typically starts at around 100 and, with the door and window closed, it pulls it down to 10, its lowest reading, in about five minutes. I'd definitely get one with a meter. And it has made a real difference to the sinus problem and it did start to get better from when I bought it. It has
almost gone.
I don't run it all the time as it does clear the room pretty quickly. I run it during peak-hour traffic and for a few more hours during the day. But I don't bother with it at night, as the traffic is low, and I'd rather have the window open than use the air-con; except that I run it for a half an hour or so when I go to bed; after I close the window, again. But it probably would be better to run it for longer. It is rather surpizing how much pollution gets in even with the window and door closed and even blocking the gap under the door.
The noise of this one, in the small room that I'm in (5mx3m), is a problem. The volume isn't bothersome but it does seem to have a high-frequency component as it does set my tinitis off, a little; but it's nothing compared to the window-rattler of an air-con unit that I also have (a necessity in the Brisbane summer: the air-con, not a noisy one), and I wear ear-plugs for that, anyway, so it doesn't make much difference to me. But if you have somewhere a little out of the way to put the air-filter, it would probably be fine.
Regarding dusting, my situation is probably unusual because of the dust (it was bad enough to short out a computer, once), but, while it does still become dusty, it is much less than it was.
I couldn't recommend a particular brand. While the Devanti is quite servicable, there are better ones about, now. I saw a good-looking, Hitachi one at Big W going for about A$200 that I would've bought if it was around when I bought mine. After the fires last summer, they've become a big thing in Australia, now, and prices have dropped quite a bit. They're no longer the specialist kit that they were before.