Field Monitoring of Carbon Dioxide in Vehicle Cabin to Monitor Indoor Air Quality and Safety in Foot and Defrost Modes

Experimental tests were conducted to monitor cabin carbon dioxide concentrations by driving the vehicle in Farmington Hills & Detroit area. The number of occupants, vehicle speed, and type of driving (local traffic and highway conditions) are the major variables for this study. The tests were conducted during winter season with HVAC unit operating in foot and defrost modes. For foot and defrost modes, there are some noticeable differences in the magnitudes of the carbon dioxide concentration due to the airflow rates and mixing of air within the cabin. The measured peak cabin carbon dioxide levels in foot and defrost modes were found to be of similar magnitudes. However, the initial build-up rates of cabin carbon dioxide for defrost modes were higher in defrost modes in comparison to the foot mode. This is due to different mechanism of mixing of air within the cabin. This is explained in details in the paper.