Understanding UV Dosage, Intensity and the kill rate

UVC is widely used to disinfect the air and surfaces. Each microbe requires a specific UV dosage for its DNA and RNA to be completely damaged. In other words, the UV dosage for bacteria and virus are different from each other. Each UV lamp manufacturer specifies UV intensity in µW/cm2 (reads microwatt per square centimeter), and it is very important to determine the relation between UV Dosage and UV intensity, to properly use the UVC equipment to deactivate the microbes.

UV Intensity is the “amount” of UV energy per square centimeter. Intensity is measured in watt per square centimeter (W/cm2). On the other hand, UV dosage, measured in Joules per square centimeter (J/cm2), is the amount of UV energy applied over “a period of time”.

Example: A lamp generating 20 µW/cm2 of UV radiation for 1 minute (60 seconds) will give out

Over the last couple decades, scientist published accurate data on the UV dosage required to deactivate pathogens by 99.99%. Based on the published results, we can calculate the “amount of time” required to deactivate each one of those pathogens. The amount of time required to deactive the pathogens is called “exposure time”.

Example: SARS-Cov-2 (Covid19) requires 50 mJ/cm2 of UV dose to kill by 99.99%. Let’s say the UV intensity of a UV lamp is 0.4 mW/cm2 measured at 1 mt away from the lamp. Then, the exposure time needed to kill Covid19 by 99.99% is:

So, it takes 125 seconds to kill (deactivate) Covid 19 virus by 99.99% using a lamp of intensity 0.4 mW/cm2

The higher the UV intensity, the faster it kills

With the high-intensity UV lamps, you would only require less exposure time to deactivate the pathogens. 

The dosage to kill a pathogen is always constant and listed in scientic journals. Therefore, the above equation can be re-written as:

This indicates that the higher intensity lamp will kill microbes much faster. In other words, select a UV light with higher intensity if you want faster and effective disinfecting rates.

Ex: Consider UVKLEEN 300W which has an intensity of 1.35 mW/cm2 at a distance of 1 meter from the lamp. This lamp would only require:

Consider a competitor with UV intentisy of 0.7 mW/cm2. This lamp would require:

UVKLEEN 300W lamps take only 37 seconds to kill Covid19 by 99.99% at a distance of 1 meter from the lamp. And the competitor takes about 71.4 seconds to perform the same action. Click here to see the complete list of pathogens and its exposure times using UVKLEEN 300 series. Click here to see the exposure times required to kill the most common virus, bacteria in a facility. 


Want to get rid of the Covid'19 outbreak. We have designed the UVC Systems or Products to kill the Corona Virus, bacterias, and pathogens.