## UV-C Irradiation Dosage for Different Disinfection Applications

##### Date:Jan 13, 2021

With the rapid growth of UV-C LED applications in sterilization and disinfection applications, there is an increasing need to quantify and determine whether a specific UV-C lamp or device can achieve the purpose of disinfection. Unlike conventional lighting products, we can visually confirm whether it is "bright enough", while UV-C is invisible to the naked eye, which is particularly challenging from a measurement point of view. In this article, we will introduce the main measurement methods and principles, and then work through a few examples that will help complete the steps required to determine the irradiance requirements for a particular setting.

Dosage = amount of UV × time

First of all, we need to start with the UV-C dose, because the ultimate goal is to reach a certain UV-C dose required to inactivate pathogens. But first, what exactly is the dose? How to measure?

UV-C dose (also called exposure dose or fluence) is a method used to measure the total amount of UV-C energy that has been irradiated on a specific surface. This is the most critical element in the design of the UV-C system, because the UV-C dose is the main determinant of whether we successfully achieve pathogen inactivation.

The dose depends not only on the intensity of UV-C falling on the surface, but also on the time that the surface is exposed to UV-C radiation. In other words, if other conditions are the same, a UV-C lamp with an intensity increased by half can be used for twice the time, and the same UV-C dose can be obtained.

The intensity of UV-C falling on the surface is called irradiance, and the unit is W/m² (or some change in power per unit surface area). The exposure time is in seconds.

The simple form of the formula is as follows:

Exposure dose (J /m²) = ultraviolet radiation (W /m²) x time (seconds)

We can also verify this by looking at the unit agreement here (1 Joule = 1 Watt)-second).