al Conditions for Human Occupancy (ASHRAE, 2004). ASHRAE 62.1-2007: Ventilation for Acceptable IndoorAir Quality (ASH RAE, 2007). ASTM D 6245-1998: Standard Guiclefir Using Indoor Carbon Dioxide Concentrations to Evaluate Indoor Air Quality and Ventilation (ASTM,1998). 13. Definitions The breathing zone is the region within an occupied space between 3 an