Application Note

The Dangers of Ultraviolet Rays and Handling Precautions
for UV LEDs

Table of contents
・ ・ ・ ・ ・ ・ ・ ・ 2

1. Ultraviolet Light Information
2. Cautions

・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 3

3. How Ultraviolet Rays Affect the Human Body ・ ・ ・ ・ 4
4. Handling Precautions

・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 4

5. Ozone Generation from UV Rays
6. Summary・ ・ ・ ・ ・ ・ ・ 5

・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ 5This document contains tentative information, Nichia may change the contents without notice.

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The Dangers of Ultraviolet Rays and Handling Precautions for UV LEDs
1. Ultraviolet Light Information
UV LEDs are LEDs that emit ultraviolet rays. Ultraviolet rays have shorter wavelengths than visible light; they are
generally defined as electromagnetic rays with wavelengths ranging from 10 to 400nm.
There are three categories depending on the wavelength:
UV-C (200-280nm), UV-B (280-315nm), UV-A (315-400nm)
10nm

400nm
UV

X-ray

V-UV
10~200nm

UV-C
200~280nm

UV-B
280~315nm

UV-A
315~400nm

780nm

VisibleInfraredLightThe key features of UV-C, UV-B, and UV-A are summarized below.
UV-C (200-280nm):
It is absorbed by the atmospheric layer (the ozone layer) and therefore does not normally reachthe earth’s surface. Due to its strong disinfectant properties, it is highly dangerous to livingorganisms.
UV-B (280-315nm):
Most of this is absorbed by the atmospheric layer (99.5%) though some reaches the surface andis harmful to skin and eyes. This can cause sunburns and skin cancer.
UV-A (315-400nm):
Approximately 5.6% passes through the atmospheric layer without being absorbed and reaches
the surface. Although it is not as harmful as UV-B, prolonged exposure may affect health.
This document contains tentative information, Nichia may change the contents without notice.

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The Dangers of Ultraviolet Rays and Handling Precautions for UV LEDs
2. Cautions
The UV LEDs emit strong ultraviolet rays (i.e. UV-C, UV-B, and UV-A) during operation.
When handling the UV LEDs, it must be ensured that the eyes and skin are not directly exposed to theultraviolet rays. Even reflected or leaked rays are harmful.

UVUV

Do not directly view the UV rays.

Reflected UV rays are also harmful.

UVUV

Do not directly expose skin to the UV rays.

Leaked UV rays are also harmful.
This document contains tentative information, Nichia may change the contents without notice.

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The Dangers of Ultraviolet Rays and Handling Precautions for UV LEDs
3. How Ultraviolet Rays Affect the Human Body
Dangers of ultraviolet rays (eye damage)
Intense ultraviolet is dangerous to the eyes and can cause snow blindness (photokeratitis), ultraviolet eye
infections (electro-optic ophthalmitis), cataracts, pterygium, and pinguecula.
Dangers of ultraviolet rays (skin damage)Proteins are one of the most important components of living organisms. Ultraviolet rays can denature proteins.
When the skin is exposed to UV light, it damages collagen fibers and elastic fibers. This results in aging of theskin, damage to DNA, and risk of skin cancer.

4. Handling Precautions
When performing a measurement of the ultraviolet rays with a UV illuminance meter, a camera, etc. and/or alight-up test for the UV LEDs, ensure that they are done in an enclosed area to prevent direct exposure of theeyes and skin to the ultraviolet rays. Unintended exposure may occur if the area is not completely sealed. To
reduce the damage that may be caused by exposure, wear appropriate protective clothing and gear (i.e. gloves,
thick clothing with long sleeves, a face mask, goggles, etc.).
Ensure that both the operators who actually handle the UV LEDs and personnel who may be around the UVLEDs fully understand the dangers of ultraviolet rays and are protected from exposure as appropriate.

This document contains tentative information, Nichia may change the contents without notice.

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The Dangers of Ultraviolet Rays and Handling Precautions for UV LEDs
5. Ozone Generation from UV Rays
At wavelengths of 100-230nm, it can react with oxygen in the air to produce ozone.
Ozone is a powerful oxidizing agent (several times more powerful than chlorine).
Due to its powerful oxidizing properties, ozone can deteriorate rubber and plastics and may affect the humanbody depending on the concentration.
The figure below shows examples of the spectrums for Nichia's UV LEDs; Nichia’s UV LEDs will not generate ozone.

0.8Ozone generation (100~230nm)

Relative Emission Intensity (a.u.)

1.0

0.6

0.4

0.2

0.0
200

6. Summary

230

250

300

350

400450Peak Wavelength (nm)As described in the previous sections, ultraviolet rays can be harmful to the human body; however, they can be
useful if they are used properly.
When handling and/or using Nichia's UV LEDs, and/or designing a chosen application that uses Nichia's UVLEDs, ensure that all applicable laws and regulations are followed for the intended use and/or in the concernedcountries/regions.
This document contains tentative information, Nichia may change the contents without notice.

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The Dangers of Ultraviolet Rays and Handling Precautions for UV LEDs
Disclaimer
This application note is a controlled document of Nichia Corporation (Nichia) published to provide technicalinformation/data for reference purposes only. By using this application note, the user agrees to the following:・ This application note has been prepared solely for reference on the subject matters incorporated within it and Nichia
makes no guarantee that customers will see the same results for their chosen application.
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TOKUSHIMA 774-8601, JAPAN
Phone: +81-884-22-2311 Fax: +81-884-21-0148
This document contains tentative information, Nichia may change the contents without notice.

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