When an idling car is nearby, it is generally better to close your windows to minimize your exposure to pollutants and potentially harmful emissions. Idling vehicles can release pollutants such as carbon monoxide, nitrogen oxides, and particulate matter into the surrounding air, which can have adverse effects on your health.
While fresh air is important, it's important to note that the air quality outside can be compromised in the presence of idling vehicles, especially in areas with heavy traffic or congested conditions. Closing your windows helps create a barrier that reduces the amount of pollutants entering your vehicle's interior, thereby minimizing your exposure.
If you are in a situation where you need ventilation but want to reduce exposure to outside pollutants, you can make use of the recirculation mode on your car's HVAC system. This mode recirculates the air within the vehicle without drawing in air from the outside, helping to maintain a cleaner internal air environment.
However, it's worth mentioning that if you're in an area with significantly poor air quality or there are strong odors or fumes inside your vehicle, it's important to prioritize your safety and find a location with better air quality.