Wildfire Smoke

Today, wildfire smoke has hit San Francisco, where most homes don't have Air Conditioning with means of re-circulating the air over the filter - a common strategy suggested to commercial building operators to improve the Indoor Air Quality given and external Air Quality Hazard.?

For those without that option, a good strategy is to close all windows and put your air purifier to work. If needed, focus on the bedrooms and keep the doors between rooms closed to limit the amount of infiltration into your home. If you don't have an air purifier, a makeshift one can work as well (see link https://cleanaircrew.org/box-fan-filters/).

Regardless of space type and location, try using the highest MERV rating you can get. Given the small particle size (PM2.5 and less), you would need at least MERV 13 to have an impact.

Stay safe and hope this helps.