Is UVC Light Really Effective?

In the Spring Festival of 2020, affected by the new type of coronavirus, ultraviolet lights, as one of the disinfection and sterilization solutions, have been on the stage of public. UVCLED ultraviolet disinfection lights can interrupt the DNA and RNA of the bacteria in the aerosol, thereby preventing the replication and reproduction of the virus, and killing the bacteria.

Ultraviolet (Ultraviolet-UV) is invisible light, which is invisible to the naked eye. Ultraviolet has a wavelength of 10 to 400 nanometers (nm), and is divided into three categories according to its wavelength, including UVA, UVB and UVC. The shorter the wavelength, the higher the intensity. Therefore, UVC has the highest intensity among the three types of ultraviolet rays.

Principle of UV sterilization

Ultraviolet rays act on the genetic material of biological cells, which is DNA, to destroy the DNA and cause the death of bacteria; in addition, ultraviolet rays of a specific band can interact with oxygen in the air to produce a strong oxidizing sample, thereby killing bacteria.

What kind of UV can be used to sterilize?

Research has shown that the UVC band (200-280nm) is the most bactericidal part of ultraviolet rays.

For different microorganisms, the bactericidal effect of different wavelengths is different. Ultraviolet rays have a good bactericidal effect on major infectious diseases such as dysentery, cholera and enteritis.

According to the technical standards of disinfection and sterilization, each microorganism has a specific UVC killing dose (irradiation intensity·time) standard.

Can ultraviolet light kill the coronavirus?

Coronavirus is a single-stranded positive-stranded RNA virus that is protein-encapsulated. In addition to the new coronavirus (2019-NCover) discovered this time, the most well-known SARS and MERS coronaviruses are.

Studies during the SARS period found that SARS virus is sensitive to heat radiation and UVC, and UVC with an intensity greater than 90μW/cm² can kill SARS virus for 30 minutes.

The researchers also simulated daylight under natural conditions in the laboratory, and found that under the fine weather at 10 am in Beijing in May, that is, when the ultraviolet intensity is 4μW-5μW/cm², 3 hours can kill the external coronary virus.

How long does it take to disinfect with ultraviolet light?

When using ultraviolet lamps for disinfection, the length of the disinfection time needs to be determined according to the temperature and humidity of the room.

Generally speaking, the disinfection time is generally no less than 30 minutes, especially when the temperature is lower than 20°C or higher than 40°C, and the relative humidity is greater than 60%, the disinfection time must be extended.