Secondary aerosolization of viable Bacillus anthracis spores in a contaminated US Senate Office.
BACKGROUND
Bioterrorist attacks involving letters and mail-handling systems in Washington, DC, resulted in Bacillus anthracis (anthrax) spore contamination in the Hart Senate Office Building and other facilities in the US Capitol's vicinity.


OBJECTIVE
To provide information about the nature and extent of indoor secondary aerosolization of B anthracis spores.


METHODS
Stationary and personal air samples, surface dust, and swab samples were collected under semiquiescent (minimal activities) and then simulated active office conditions to estimate secondary aerosolization of B anthracis spores. Nominal size characteristics, airborne concentrations, and surface contamination of B anthracis particles (colony-forming units) were evaluated.


RESULTS
Viable B anthracis spores reaerosolized under semiquiescent conditions, with a marked increase in reaerosolization during simulated active office conditions. Increases were observed for B anthracis collected on open sheep blood agar plates (P<.001) and personal air monitors (P =.01) during active office conditions. More than 80% of the B anthracis particles collected on stationary monitors were within an alveolar respirable size range of 0.95 to 3.5 micro m.


CONCLUSIONS
Bacillus anthracis spores used in a recent terrorist incident reaerosolized under common office activities. These findings have important implications for appropriate respiratory protection, remediation, and reoccupancy of contaminated office environments.
Weis
Christopher P
CP
US Environmental Protection Agency National Enforcement Investigations Center, Denver Federal Center, Bldg 53, PO Box 25227, Denver, CO 80225, USA. weis.chris@epa.gov
Intrepido
Anthony J
AJ
Miller
Aubrey K
AK
Cowin
Patricia G
PG
Durno
Mark A
MA
Gebhardt
Joan S
JS
Bull
Robert
R
D000336:Aerosols; D016902:Air Pollution, Indoor; D001408:Bacillus anthracis; D023482:Bioterrorism; D004219:District of Columbia; D004783:Environmental Microbiology; D004784:Environmental Monitoring; D035082:Federal Government; D006801:Humans; D013171:Spores, Bacterial; D037041:United States Government Agencies; D017132:Workplace
D000336:Aerosols