Airborne Spore Exposure in Typical School Buildings

Abstract

RATIONALE: Air quality in public school buildings has been of increasing concern to parents of children with asthma and allergies. To examine the indoor airborne spore levels in typical school buildings, the following studies were conducted. METHODS: Six school buildings in 1 school district were evaluated for indoor spore levels. Airborne spores were collected using an Allergenco MK3 spore trap and evaluated microscopically for 25 fungal taxa. Collections were made during the school year between September and June. All school buildings were heated and air-conditioned and none had obvious HVAC problems. RESULTS: At the sites we made 260 indoor and 37 outdoor collections. Mean total spore counts were 467 per cubic meter indoors and 8470 outdoors. Mean indoor total spore count for individual schools varied from 105 to 625 and mean indoor Apergillus/Penicillium spore counts varied from 0 to 136. Cladosporium and Ascospores were the 2 taxa most frequently observed (97% and 94% respectively). Aspergillus/Penicillium spores were found in about 7% of collections and Stachybotrys spores were only seen in 2 of the indoor collections (< 1%). CONCLUSIONS: We conclude that spore levels in typical public school buildings are relatively low, often less than 10% of outdoor spore levels. Spores typically associated with damp indoor environments are likewise infrequently found. High concentrations of spores in school buildings (over 1000 per cubic meter) should therefore be considered unusual.