So I finally broke down and bought a good air purifier after someone came into my home wearing cologne and it took 3 days to air out the house. Having all the windows and doors open when it's well below freezing and snowing to air the house out for days just isn't possible every time someone 'forgets' when they come over. Especially with the neighbours on one side being smokers and the neighbours on the other using dryer sheets and laundry scent boosters.
It seems to work well. Our house doesn't stink, but it did seem fresher after having the purifier running on low for several hours.
Every 5 year filter replacement.
It's an expensive unit, but I think it was worth the money to try to save my health a little. The boyfriend was not happy with how much I spent, but then I showed him the units specific for chemical sensitivities that start at twice the price (and this one is already really expensive) and he shut up.