Due to local geography trapping wildfire smoke, last week SLC, UT, USA hit over 200 and even walking to the mailbox without a mask on was uncomfortable. My frie

Due to local geography trapping wildfire smoke, last week SLC, UT, USA hit over 200 and even walking to the mailbox without a mask on was uncomfortable. My friends were wearing N95s and respirators when walking to their cars and using the recirculation setting. My HVAC filter was dark with smoke particles.