What Causes Bad Indoor Air Quality?

There are many causes of air pollution in homes, workplaces, and elsewhere. These sources are very diverse and sometimes pose different kinds and degrees of health risks.
To gain a fuller understanding of the magnitude of the problem, it will perhaps be helpful to examine some of causes of air pollution inside buildings.
Anion air purifier can effectively removes smoke, pollen, dust, animal dander, dust mites, molds, bacteria and viruses. So using air purifier purify indoor air is recognized as one of the way to improve indoor air quality internationally.