A quality air purifier from a reputable company will definitely improve the air quality within the house.
Common indoor air pollutants include such things as dust, pet hair, dander, pollen and volatile organic compounds responsible for the various – for lack of a better word –"aromas" in a house. This could be from cooking, perfume, cleaning products or even people and pets. Both are bad for you as they can irritate your eyes, nose, and throat, and are even more problematic if you have other health complications such as asthma.
There are many air purifiers on the market that use Hepa filters, so you would just need to choose one from a reputable manufacturer that is able to clean the air for the room it is in. Basically, a bigger room needs a larger unit to effectively filter the air in a reasonable amount of time. Also, if your home is air-conditioned, check to see if it uses Hepa filters as some consumer units boast the feature.An air ioniser releases negative ions into the air that attach themselves to tiny particles such smoke or dust, causing them to clump together so that they fall out of the air and stick to surfaces thus"cleaning" the air of those particles.