You don't need to do the experiment, it's already been done.
Studies were carried out into the amount of pollution ingested by cyclists and pedestrians in comparison to drivers. The study had initially expected to show that pedestrians and cyclists were being unduly affected by air pollution caused by road traffic. What the studies did show that pedestrians and cyclists did ingest more large particulate pollution, occupants of motor vehicles were shown to ingest larger volumes of the small particulate pollution. The smaller particulate pollution is the more harmful and more likely to cause cardiac and respiratory disorders. Tests were conducted on modern vehicles with closed windows so the majority of the pollution was coming through the air filter.
If enough of the particulate matter in pepper spray is small enough, it's going to pass through an air filter. Same as when you can tell someone has run over a skunk from several miles downwind while driving along a highway.