Should the Air Conditioning Be Set to Internal or External Circulation During Long-Term Parking?

[StAllie]

Keeping the air conditioning on internal circulation during long-term parking will gradually lead to polluted air inside the vehicle, increasing harmful gases and posing risks to human health. It is advisable to periodically switch to external circulation or leave a small gap in the window to allow fresh air in. Continuous use of internal circulation can result in carbon dioxide poisoning. The choice between internal and external circulation should be adjusted based on actual conditions. Use external circulation on highways: First, due to wind resistance and high speeds, opening windows is not advisable on highways. Prolonged use of internal circulation can cause brain hypoxia, impairing reaction time and judgment, which is highly dangerous. Second, the air quality on highways is generally good, with low concentrations of exhaust fumes, making external circulation a suitable choice. In urban areas, during congested traffic or peak commuting hours when vehicle exhaust concentrations are high, it is best to switch to internal circulation. New cars typically contain high concentrations of toxic gases like formaldehyde. For the first three to six months after purchasing a new car, it is recommended to use external circulation along with opening windows to enhance air circulation and dilute the concentration of toxic gases inside the vehicle.