I would recommend monitoring for specific hazards. To satisfy New York State Department of Health standards, my laboratory must perform biannual hazard exposure monitoring for all lab personnel. There are personal monitors that assay for a variety of hazardous chemicals: http://www.labsafety.com/personal-monitors_24532949/?searcht... These are submitted to a reference lab after completing a time-weighted exposure and the results come back within a week or so. Of course "air quality" is drastically different in an office versus a laboratory, but the process of eliminating potential threats rather than trying to quantify how "good" your ambient air is more practical and applicable.