The corregimiento of San Carlos is the seat of the district of the same name, in West Panama. The Pan-American Highway crosses its territory from east to west, its south side faces the Pacific Ocean, and fishing, cattle raising, farming and tourism are among its activities.
With the countryside, the highway and the sea so close, outdoor dust and damp air can get into the premises, and both end up in filters, grilles and ducts. The businesses tend to be small. Because the crew travels from the city, each visit is agreed in advance with the management, and premises close to one another are put together in a single round. San Carlos is about 97 km by road from the Climatiza office, in an approximate calculation.
Data point: A study of air conditioning cooling coils found that their microbial ecology depended on the outdoor climate through the dew point, and that low-efficiency filters (MERV 8) were associated with a greater abundance of certain groups of bacteria and fungi than MERV 14 (Bakker et al., Indoor Air, 2020).