Alternative Room Disinfection Modalities –Pros and Cons - Use of Biocidal Surfaces for Reduction of Healthcare Acquired Infections - page 196

dead microbes are revived after exposure to longer wavelength radiation due to
DNA repair mechanisms [ 97 ]. The longer wavelength light provides the energy for
this DNA repair. A final concern is that many healthcare facilities are attempting to
minimize the presence of mercury in the environment. Ultraviolet lamps, if broken
will spill elemental mercury into the immediate area [ 62 ].

9.4 Discussion

This chapter described the purpose for and risks and benefits of the use of chemical
fumigation and UVC irradiation for surface disinfection. See Table 9.2 for a
summary of pros and cons of these alternative modalities. This study looked at
the efficacy and effectiveness of fumigation in institutional environments. There are
other areas that frequently use this practice, and by observing consequences of
fumigation in other environments, the findings may be analyzed for relevance in
healthcare or research institutions. One of the most common uses of fumigation is
for the control of pests and mold in homes and other buildings. The standard
approach is to evacuate people and pets and then fill the space with a gaseous
pesticide to kill the target organism. A similar method is also used in controlling
pests in soil, grain and produce. The record of fumigation safety suggests that even
industries with many years of experience with chemical fumigation still have over
exposure incidents.
A number of chemicals have been used over the years to clean and disinfect
critical environments. For example, formaldehyde will kill microorganisms, includ-
ing their resistant spores, but as Krause points out, it is slow, difficult to generate

Table 9.2 Pros and cons of chemical fumigation and UVC germicidal irradiation for surface
disinfection
Modality Con's a Pro's

Fumigation Chlorine dioxide Good biocidal properties

on all surfaces, a gas
that will easily disperse
throughout a space

Highly toxic (TLV ¼ 0.1 ppm,
STEL ¼ 0.3 ppm), must be
generated on site, may
damage surfaces & equipment

1 ppm), less
effective on porous surfaces,
no easy method to monitor
HPP plus silver Same as HPP Same as HPP & no method to
measure silver exposure
UVC irradiation Easy to administer Limited efficacy data, many
challenges including variabil-
ity in organism susceptibility,
limited to RH range of
50-60 %, assuring minimum
contact distance,
photo-reactivation likely
a Containment of the gas, vapor, or radiation is essential to prevent human exposure

Hydrogen peroxide
plasma (HPP)

High kill rate on hard
surfaces, easier to
generate

Toxic (TLV

¼