Question

When the outdoor air quality is bad, is it better to run your HVAC fan constantly?

Answer 1

If the outdoor air quality is bad, you want to close your place up as tightly as possible and yes, run the HVAC fan as needed. You may well hold a more constant temperature throughout your building by running that blower constantly, but the light bill will reflect that extra usage as well.

Answer 2

Whenever the fan is on,air is going through furnace filter. Leave it continuously and you are likely to see less dust around. It is also important to have a good filter. 

Answer 3

The EPA suggests that systems use mechanical ventilation in order to avoid pollutants in buildings and ductwork, an excess of moisture, and odor buildup. Fresh air allows for the space to cleanse itself as the air flows through and helps keep down any undesirable air from doing too much damage.