What exactly are UV rays?

In 1878, a scientific paper was published by Arthur Matthew Weld Downing and Thos. P. Blunt published a scientific paper depicting and investigating the effect of light on bacteria and other organisms.

General principles

In 1878, a scientific paper was published by Arthur Matthew Weld Downing and Thos. P. Blunt published a scientific paper depicting and investigating the effect of light on bacteria and other organisms.

https://royalsocietypublishing.org/doi/10.1098/rspl.1877.0068

Further studies followed with sunlight until artificial light sources were used and effects of monochromatic UV radiation were published by A. Hollaender in various publications starting in 1938.

https://books.google.de/books?id=zoFAu0APLjIC&pg=RA2-PA53&dq=Abiotic+and+Sublethal+Effects+of+Ultraviolet+Radiation+on+Microorganisms&hl=en&sa=X&ved=2ahUKEwirur3RpPzqAhVS66QKHaP8CDgQ6AEwAHoECAMQAg

At present it is known that the most effective radiation for killing microorganisms is between 240 nm and 270 nm and this is UV-C radiation.

What exactly are UV rays?

Just like light or radio waves (FM / VHF), UV radiation belongs to the electromagnetic wave radiation, which differ from the wavelength in the electromagnetic spectrum. For example, radio waves have the longest wavelengths and could be longer than a soccer field, for example. For submarine radio, waves can be several tens of kilometers long so that messages can be transmitted over long distances. Wave radiation is specified in wavelength and in frequency (1/s). It is 3 to 30 kHz for very low frequency (VLF) waves and 30 to 300 kHz for low frequency (LF) waves. For the broadcasting service, the frequencies of 87.5 - 108 MHz are known. The frequencies from 174 - 223 MHz are reserved for digital broadcasting DAB.

The electromagnetic spectrum has various properties, including a part of the spectrum with visible light, which can be detected by our eye. It ranges from red (750 nm) to violet (400 nm). Thus we see only a limited part of the electromagnetic spectrum, for the remaining part we fall back on technical aids (e.g. radio) and could take up this information.

The ultraviolet range is divided into different ranges and can be found in the order of 380 nm to 1 nm. The frequency in this range is 789 THz to 300 PHz and thus already has enough energy to damage cells. The best example here is the direct influence of UV radiation on our skin when exposed to the sun for too long. The sun does not only radiate in visible light, but also in the infrared and UV range.

The range of UV-C radiation extends in the range of 100 - 280 nm and is the most energy-rich part of optical radiation. Due to this high-energy radiation, UV-C radiation can damage genetic material and thus has a killing or inactivating effect on microorganisms and viruses.

Different microorganisms have an individual sensitivity to irradiation with UV-C, which means that a high UV-C power is necessary to perform the irradiation effectively.

Calculations of the UV-C radiation dose for inactivation

In order to perform effective irradiation, simulations and calculations and knowledge of radiation power, irradiance and radiation dose are necessary.

Our air purifiers combine four technologies in one:

HEPA H13/H14 filters, active and coarse filters and UVC irradiation.

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