How does UVC kill bacteria and viruses?
UVC light inactivates pathogens by breaking the hydrogen bonds in their DNA or RNA. This stops them from replicating and renders them harmless.
The most effective germicidal UVC wavelength is around 264 nm.
Required dose for UVC sterilization
Different pathogens require different UVC energy doses to be inactivated:
- Some bacteria: as little as 20 J/m²
- Resistant bacteria or viruses: may need 500 J/m² or more
- Fungi, yeast, and mold: can require up to 10,000 J/m²
These large variations highlight the importance of selecting the right system and dose for your specific application.
Understanding UVC disinfection levels
The effectiveness of UVC disinfection is typically expressed as a percentage reduction of a microorganism population. As shown in the diagram, each step toward a higher reduction level requires exponentially more energy:
| Reduction Level | Description |
|---|---|
| 90% | Standard minimum disinfection goal |
| 99% | Requires double the energy |
| 99.9% | Doubles again |
| 99.999% | Rare – requires very high energy |
This exponential increase illustrates why 100% sterilization is not achievable—regardless of whether you use UVC light or chemicals. A small portion of any microbial population is likely to survive, which is why realistic expectations and tailored system design are critical.
Real-world vs. laboratory results
Be cautious when reading lab-based claims. The UVC dose needed in a real production environment may be much higher than what works in controlled, clear-water tests.
Environmental factors such as:
- Shadowing
- Surface roughness
- Airflow
- Distance to source
Can significantly impact the disinfection effect.
Read more about UVC surface treatment
Why experience matters in UVC sterilization
Choosing the right UVC system means understanding:
- Your target pathogens
- Required exposure time
- Room layout and air movement
- Operational safety and compliance
Need help assessing your UVC system? Get in touch to learn how Natdis can assist you.
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