When designing, building or installing a UV light, two key questions must be answered first:
"How irradiance does it need to have?"
"What is the required exposure time?"
While there are many studies that show the effectiveness of UV light in disinfection or sterilization, a high variance of the results exists, which presents a challenge to find an answer to these questions.
We will present our recommendations by analyzing the results of 413 reasearch papers, as found in the compilation "Fluence (UV Dose) Required for up to 99% disinfection from Viruses, Bacteria, Protozoa and Algae" that can be downloaded at the links below:
The research studies present the fluence required to achieve a log reduction from 1 to 5, for different types of UV sources.
The effectiveness of sterilization or disinfection with UV light depends on the exposure, time, wavelength and irradiance.
- Exposure or fluence (sometimes called dose) is measured in mJ/cm2 (where 1 mJ/cm2 = 10 J/m2)
- Exposure time is measured in seconds (s), minutes (m) or hours (h)
- Irradiance is the flux of radiant energy per unit area, in other words how much of the UV radiation power (measured in W = 1000 “miliwatts” mW = 1.000.000,00 “microwatts” μW ) reaches the surface. Irradiance is measured in mW/cm2 or W/m2 (1 mW/cm2 = 10 W/m2) and is dependent on the radiant power, distance and dispersion of the radiation emitted by the lamp source.