The air exchange rate depends heavily on vehicle speed, ventilation setting, window positions mainly control the air exchange rate (ACH)

Parked Car:

• AC off: 0.42 – 1.09 per hour

• AC on: 1.96-3.23 per hour

• AC off and fans on: 8.7-10.7 per hour

• windows closed and no mechanical ventilation: 1.0 – 3.0 per hour

• ventilation set on recirculation: 1.8-3.7 per hour

• windows closed and fan set on fresh air: 13.3-26.1 per hour

• windows open and no mechanical ventilation: 36.2-47.5 per hour

Moving Car (28 km/hr):

• window open and no ventilation: 71 per hour

• window closed and ventilation on: 60 per hour

• windows closed and no ventilation: 4.9 per hour