The inactivation and removal of airborne Bacillus atrophaeus endospores from air circulation systems using UVC and HEPA filters.
OBJECTIVE
To (i) evaluate the UV radiation in the 'C' band/high efficient particulate air (UVC/HEPA) instrument's potential to inactivate spores of Bacillus atrophaeus and selected Bacillus species and (ii) test whether a titanium dioxide coating inside the cylindrical HEPA filter improves the system's efficacy.


RESULTS
Known amounts of dried spore preparations of B. atrophaeus, Bacillus cereus, Bacillus megaterium, Bacillus stearothermophilus and Bacillus thuringiensis were exposed to the UVC lamp within a cylindrical HEPA filter for different time lengths (30 min to 48 h) and with different air flow speeds (0-235 l s(-1)). The log(10) reduction (range 5-16 logs) of colony forming units for spores exposed to the UVC compared with the unexposed spores was significant (P < 0.0001). The addition of a titanium dioxide (TiO(2)) veneer to the interior surface of the HEPA filter significantly increased the inactivation of spores (P < 0.0001).


CONCLUSIONS
The UVC/HEPA unit could inactivate spores of B. atrophaeus, B. cereus, B. megaterium, B. stearothermophilus and B. thuringiensis.


CONCLUSIONS
The UVC/HEPA unit represents an effective method of decontaminating circulating air within an air-duct system as found in a building.
Luna
V A
VA
Center for Biological Defense, College of Public Health, University of South Florida, Tampa, FL 33612, USA. vluna@health.usf.edu
Cannons
A C
AC
Amuso
P T
PT
Cattani
J
J
D000389:Air Conditioning; D000391:Air Microbiology; D001407:Bacillus / Q000528:radiation effects*; D003666:Decontamination / Q000379:methods*; D005374:Filtration / Q000379:methods; D013171:Spores, Bacterial; D014466:Ultraviolet Rays