Many people are asking themselves this question in recent weeks. The quick answer is this: I’m not sure, I’m not a scientist of that sort, but chances are the air in your vehicle is being filtered. Starting around the early 2000 model-years, most vehicles were equipped with a cabin air filter, also referred to as a pollen filter. These filters clean the outside air before it enters the inside of the car. They also filter the air as it’s re-circulated around the cabin, if the occupant selects that option. The filters come in several different price points, with quality being measured at filtration ability in parts-per-million (ppm). Some of the highest quality filters use charcoal to help filter out particulates and pollens. The filters are changed at scheduled intervals when the vehicle is serviced during scheduled maintenance. The filter can be changed more often, as needed, at a relatively low cost. Many people aren’t aware that a filter can be plugged more than 20-25%, and still look completely clean. Particles measured in PPM are very small!
How it works is like this: The blower fan for the heating and air conditioning can either pull air from outside or inside the car. By selecting the recirc option, the car closes a flap inside the airflow ducting, forcing the blower to recirculate the air inside the cabin instead of drawing “fresh” air from outside. Coincidentally, the recirc option makes your AC work much better, as the system is now cooling air that has already been cooled, instead of continuously trying to cool much hotter air from outside. If we end up dealing with smoke again, keep all the windows and flaps closed, and after it’s all done, call and schedule your vehicle for scheduled maintenance and/or engine and cabin air filter changes. Thanks to all the brave people fighting fires to keep us safe this fire season. Drive on!