commercial uv sterilizer
HOW IS THE PERFORMANCE OF A UV DISINFECTION DEVICE DETERMINED?
The main ways UV device companies to substantiate performance are
Dose-response models, where UV-dose is measured, then used to
estimate device effectiveness in hospitals.
Tests conducted in microbiology labs, where rate-of-kill is
measured for various pathogens under tightly controlled conditions.
Environmental effectiveness tests, where hospital rooms are swabbed
before and after UV treatment.
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Clinical outcome studies, where reduction in infection rates
resulting from UV device usage is calculated.
Not all effectiveness data is equally reliable. The remainder of
the article describes each category in detail, as it relates to
marketing and use of UV room disinfection devices.
MATHEMATICAL DOSE-RESPONSE MODELS AND UV DOSE-METERS (DOSIMETERS)
UV disinfection machine is a function of UV dose. The correlation is "log-linear," meaning
a line is formed when microbial populations are plotted on a
logarithmic scale at various treatment intervals. For instance, if
a study were to begin with one million microorganisms on a test
surface, it might show 100,000, then 10,000, then 1,000 viable
cells after being treated with UV light for 10, 20, and 30 minutes.
The straightforward relationship between UV dose and disinfection
is a blessing and a curse: It enables smart UV companies to build
accurate dose-response models for their machines, but fools less
sophisticated UV companies into thinking that no laboratory testing
is necessary so long as they have a way to measure or estimate UV
UV dosimeters have found a variety of uses in UV room disinfection.
Some companies use UV dosimeters to "prove" their device has
disinfected a room. Other companies use UV dosimeters to tell the
device when to turn off.
UV dosimeters are most accurate when used to measure
narrow-spectrum UV light, the kind of UV light that mercury bulbs
produce. Dosimeters are not useful to measure high-intensity
broad-spectrum UV light, since the brief pulses of broad-spectrum
light exceed the measurement capacity of most dosimeters.
Predictions based on UV dose measurements are only as accurate as
the dose-response model used to make the prediction. The use of
data from even slightly dissimilar studies (different device,
different bulb, different surface type, etc) can render predictions
unreliable. Therefore, extra scrutiny should be applied to claims
of effectiveness based solely on dose-response modeling, especially
if the source data that serves as the basis for the model was taken
from previous, unrelated studies.
If you are considering the purchase of a UV room disinfection
device based on a company's UV dosimetry data, please read more on
mathematical dose-response models for antimicrobial efficacy.