This might sound obvious, but we wanted to double check.

Regarding underground parking encloused parking (no natural ventilation at all), there always will be fans to "push" the air towards the extraction units.

Fans, in our point of view, need to be protected with plastic since they will be store on site and will for sure get covered with dust. We always require this protection.

But what about the extraction units and the ducts that take parking contaminated air outside? By contaminated air we mean air carrying CO2 from vehicules. This extraction units and duct work never carry air that will be "breathed" by people. Our assumption is that these do not need to be plastic protected.

Are we correct?