Last year when the west coast was blanketed in smoke, I setup a box fan with a HEPA filter. It probably helped, but we also found that the fan's motor was working really hard. The cord's connection point to the fan started melting (unbeknownst to us), causing the fan to intermittently cut out. I only noticed the problem when, long after the forest fires were gone, we noticed a strong smell of melted plastic coming from the fan itself.
All in all, probably a good tradeoff to clean our air during the dangerous smoke levels, but there's the risk of burning out the motor.
All in all, probably a good tradeoff to clean our air during the dangerous smoke levels, but there's the risk of burning out the motor.
Be careful out there.