On the west coasts of Canada (BC) we've had insane forest fires the past few years and you 100% want to filter the internal air when it's extremely unhealthy outside. We're talking air quality index in the 300+ range or off the charts at times [1]. Plus, we've had these heat domes were it's in the high 30+ and just gross inside, where you really want to open the windows, but you're letting in tons of pollution. Basically, you need to cool off and filter the air at the same time.