they are the best, but sometimes hard to find the proper proper ones
i also kinda stopped using them at all in recent years because of using HEPA air filters with ionisers and such... to be honest, i would prefer teh incense plus a simple old school ioniser, just something that knocks the pm2.5 and smaller out because that's the worst of it, the hepa filters seem icky to me, after they run for a while they start to have a smell about them that is not nice, but ionisers never wear out, maybe you have to sharpen the pins every few years if they get rusty