During a Wildfire

During a wildfire event, keep all windows and doors in your home closed. If heating or cooling of the air is needed, ensure the ventilation system is turned on in recirculation mode (with outside air dampers closed) in order to filter the air.   However, the advice is different for commercial buildings. The ventilation system operators should close or limit outdoor air intake to balance the need for fresh air with the hazards of entrained smoke. Portable air cleaners, such as those with High Efficiency Particulate Air (HEPA) or electrostatic filters, may also help reduce particulate levels in both homes and offices. 
The Red Cross provides an excellent checklist for preparing for wildfires at: