Study on Air-Circulation Practices in Car Cabin

Extended use of recirculation air mode in a vehicle cabin may result in significant accumulation of carbon dioxide due to human exhalation and no inflow of fresh air, even in electric vehicles. Consequently, this will affect their health and driving ability. On the contrary, allowing outdoor air into the cabin may expose the passengers to roadway contaminants and poor odor in polluted areas. It is a constant affirmation in Malaysia that using recirculation air mode during driving would result in the best thermal comfort. Unfortunately, there has been no report on passengers’ preference for their car air-conditioning operation. This study aims to investigate the present awareness of in-cabin air quality and the practices among passengers pertaining to the ventilation of their car cabins. A set of survey questions was circulated to 211 respondents on various aspects of air-cabin conditions, including how they manage their air-circulation systems. From the survey, it was found that most of the respondents (57%) chose recirculation mode in their everyday driving, 11% for outside air mode, and 20% intermittently switched the two modes. Unfortunately, most respondents were unaware that carbon dioxide levels could be high under prolonged recirculation mode. In addition, most respondents did not know that switching on the recirculation mode for too long could be dangerous for their health.