People spend a large portion of their time indoors and thus indoor air quality has an impact on the exposure of individuals. Indoor air quality may be assessed by implementing indoor or workplace air monitoring programs, or worker monitoring programs. Monitoring data are interpreted and associated health effects are monitored. Observed health effects may be compared to expectations of effects based on the monitoring data. Interpretations are provided of requirements associated with employees' right- to-know legislation such as WHMIS and the review of regulations for potentially hazardous workplace contaminants.