Re Indoor Pollution
I generally find the obtuse verbiage of a CTWO++++ brief to be the biggest polluter.
Looking out the window and not listening is a great filter and works well year round.
If you're really stuck on model numbers I'd suggest staying away from the "Gday Worker 1000" and spend you dough on something more lasting; perhaps the "Call'n'sick 2L8" or the best model yet... The "Good Luck 'N ' Suck 2011-2015" guaranteed til 2015