CONCENTRATIONS OF AIRBORNE BACTERIA IN 100 U.S. OFFICE BUILDINGS
Original hosted in "MACE", contributed by Social Updater
This paper presents preliminary summary statistics of airborne bacteria from the US Environmental Protection Agency (USEPA) Building Assessment Survey and Evaluation (BASE) study. Air samples were collected with a single-stage agar impactor in 100 large office buildings from 1994 to 1998. Five groups of culturable bacteria were identified at two incubation temperatures: (1) Gram-positive rods, separately actinomycetes and Bacillus species, (2) Gram-positive cocci, (3) Gram-negative rods, (4) Gram-negative cocci, and (5) unknown bacteria. Bacterial concentrations were compared by: (1) incubation temperature (30 degrees Celsius and 55 degrees Celsius, respectively, for mesophilic and thermophilic bacteria), (2) sampling location (indoors and outdoors), and (3) season (summer and winter). Mesophilic bacteria accounted for more than 80% of total culturable bacteria, both indoors and outdoors. Total bacterial concentrations generally were higher and more variable outdoors but similar in summer and winter. Indoor concentrations showed more seasonal difference and Gram-positive cocci were somewhat higher in summer.