Air purifiers are best for indoor air cleaning. If you are suffering from asthma, allergies, or having problems from mold and spores, I recommend buying the best air purifier for your home. 

A high-end air purifier has three stages of the filtration system. The pre-filter is effective in capturing large particles like dust, pet hair, fur, and fungi. The True HEPA filter eliminates 99.97 % of small pollutant airborne particles like pet dander, mold, spores, pollen, and bacteria. The activated carbon filter absorbs smoke, household odors, and harmful chemicals. 

Some air purifiers offer ionizer. The ionizer emits negative ions that charge pollutant particles and clean the indoor air. If you have asthma or breathing issues, it better not to use an ionizer.