Pedregal is a corregimiento in the northeast of the Panama metropolitan area, in the Panama District, with strong commercial growth along the José Agustín Arango road: minimarkets, hardware stores, restaurants, workshops and businesses of every kind in each sector. The corregimiento also has numerous housing developments and neighborhoods.
These are modest premises, each with its own unit, open many hours in a row. In a dining room or a workshop the air also carries whatever moves around inside the premises. Since the area is about 13 km by road from the Climatiza office, in an approximate calculation, the visit is arranged beforehand with whoever runs each business.
Data point: A modeling study by Waring and Siegel (2008) estimated that filters in commercial systems collect a median of 130 g/m² per month, compared with 2.97 in residential ones. It is an estimate, which is why the actual case is inspected.