The standard is a living, working document, and the review process has sometimes been grueling. According to Dennis Stanke, a staff applications engineer with Trane, La Crosse, Wis., "Each addendum was drafted, discussed and refined by a balanced committee of industry experts and practitioners. Each addendum was issued for public review - sometimes repeatedly if needed - and revised in response to public comments."
Key changes to the standard reflect advanced understanding of air quality, moisture, air distribution, and the building as a system. Its purpose remains the same: "to specify minimum ventilation rates and indoor air quality that will be acceptable to human occupants and are intended to minimize the potential for adverse health effects." The means of reaching this goal have evolved.