To avoid carbon monoxide poisoning, should you use the heater or air conditioner in a parked car with the windows closed?

The correct answer indicates that using the heater or air conditioner in a parked car with the windows closed is not safe. This is due to the risk of carbon monoxide poisoning, which can occur when the vehicle is running in an enclosed space. In a parked car, especially with closed windows, the exhaust cannot dissipate properly, leading to a buildup of carbon monoxide, a colorless and odorless gas that can be lethal in high concentrations. The safest practice is to ensure proper ventilation when using heating or cooling systems while the vehicle is stationary. This often means keeping windows open or turning off the engine to avoid the risks associated with exhaust fumes.