EPA has several publications with lots of information about Indoor Air Quality. Indoor air can contain formaldehyde from furniture or carpets, particulates from cooking or combustion (fireplaces, candles, etc.), radon, chemicals from cleaners, other air pollution created inside the building, and air pollution from outdoors.
This list from EPA explains all their publications: guides about indoor air quality, air cleaners, duct cleaning, information for health professionals. View this information here: EPA Indoor Air Quality Publications
