This paper is a presentation of statistics made by the US environmental protection agency
BASE. A standardized protocol was used to measure bioaerosols whose air samples were
collected in 100 large US office buildings in 1994-1998. A normative data on indoor
environmental quality was thus obtained. Bacterial concentrations were compared by
incubation temperature, location, season, and climate zone.

This paper presents summary statistics of airborne culturable bacteria from the US
Environmental Protection Agency Building Assessment Survey and Evaluation (BASE)
study. Air samples were collected with single-stage, multiple-hole, agar impactors in 100
large office buildings in 1994–1998 to obtain normative data on indoor environmental
quality. Bacterial concentrations were compared by incubation temperature, location,
season, and climate zone. Forty-one percent of the samples were below the 2-or 5-min�…