Question: I am concern of the haze and the buildings
As discussed in earlier article, are we concern of haze outside or buildings inside. As the question ask and answer, air that draws from outside air PAU and fresh air intakes will impact the buildings inside. As they are drawing the dust particles whether in be 10um or 2.5um. The necessary can be equipped with MERV13 or MERV14 filters like ES13 IF and C90 Ccell. Most PAU should already have secondary filters which are MERV13 or MERV14 will be sufficient which will clear >95% of particles >1um or 1micron.
Question: Just to check do you have filters in Roll instead of Panel Pleated or Boxes
Filters in roll media are limited technical fundamental with MERV2 to MERV7 except MERV11 ES65M (disposable higher efficiency and expect a shorter lifespan)
Only ES13 IF , C90 2in thickness and other secondary filters with MERV13 or MERV13 which are constructed in pleated panel boxes or bag with high media area will be effective for haze particles. They will be able replaceable for most existing fans or aircon commercial systems without affecting airflow.