What should be avoided when using a whole-house fan?

When using a whole-house fan, it is crucial to avoid operating it in an environment where there are hazardous materials present, such as asbestos or other toxic substances in the attic. This is because whole-house fans function by drawing air from inside the house through ductwork and then expelling it into the attic and outside. If asbestos or any toxic particulates are disturbed or aerosolized by the fan's operation, they can be drawn into the home, posing serious health risks to the occupants.

Maintaining a safe and healthy environment is paramount, and using a fan in these conditions could lead to exposure to harmful substances, which could cause respiratory issues and other health problems. Therefore, ensuring the safety of the attic before using a whole-house fan is critical.

While other options address misuse of the fan’s functionality or environmental conditions, they do not present the same level of health risk associated with the presence of hazardous materials in the attic.