Mold and Other Air Impurities

My mom suffers from coughs, but only when she's here in Manila and she stays in a non-air conditioned room. My guess is that she reacts to the impurities that are in the air. The funny thing is that her problems disappear when she leaves the country. Fresher air, perhaps? We're thinking that air purifiers may help against mold and other impurities so she can cough less.