What is Ultraviolet Light? Where is it Used?
Ultraviolet Rays and Their Basic Features
Ultraviolet (UV) rays are electromagnetic waves with wavelengths ranging from 10 to 400 nm, which cannot be perceived by the human eye. Humans can only see light in the 400-800 nm range, making UV rays invisible.
UV rays are categorized into subgroups based on their wavelengths:
- VUV (Vacuum UV): 10–200 nm
- MUV (Middle UV): 200–300 nm
- UVC: 100–280 nm
- UVB: 280–315 nm
- UVA: 315–400 nm
UV rays should not be confused with X-rays, which have wavelengths of 0.1–10 nm and are typically used for medical imaging purposes.
Features of UV Rays
UV rays have higher energy compared to visible light. Specifically, UV rays with wavelengths below 125 nm and energy above 10 eV can ionize oxygen and hydrogen atoms.
- Hazards: Prolonged exposure can lead to health issues such as sunburns and skin cancer.
- Benefits: Low doses of UVB rays support the production of vitamin D in the body.
About 10% of sunlight consists of UV rays. The atmosphere filters most of these rays, with the ozone layer being particularly effective at neutralizing UVB and UVC rays.
Applications of UV Rays
1. Sterilization and Disinfection
UV rays are highly effective in eliminating microorganisms. Common uses include:
- Hospitals and laboratories: Sterilization of surfaces and equipment.
- Water treatment systems: Neutralizing harmful microorganisms.
- Personal items: Disinfection of makeup and personal care products.
In sterilization applications, the wavelength and intensity of the UV light are selected based on the intended use. The success of sterilization is verified through pre- and post-process laboratory tests.
2. Central Air Conditioning Systems
UV rays are used in central air conditioning and ventilation systems for air disinfection.
- Advantages: Reduces the impact of bacteria and viruses in the environment.
- Limitations: Effective only in areas directly exposed to the light.
Solution: Industrial ozone units are recommended for surface sterilization.
3. Personal Use
Examples of personal use of UV rays include:
- Cleaning personal items for bacterial removal.
- Eliminating harmful microorganisms in personal care products.
Effectiveness of UV Sterilization
The effectiveness of UV sterilization is measured by calculating the light flow (W/m²) and the total UV dose (J/m²).
- Light Flow: Determined by dividing the total UV optical power by the surface area.
- Total UV Dose: Calculated by multiplying light flow by exposure time.
These calculations are critical for ensuring the reliability and accuracy of sterilization processes.
