New Technology: Far UVC Ultraviolet Rays That Can Kill Coronavirus And Bacteria In The Air

According to the official website of Irvine Medical Center of Columbia University, a new study by the Research Institute found that more than 99.9% of the seasonal coronaviruses that appear in air droplets are killed when exposed to specific wavelengths of ultraviolet (far UVC) that are safe to humans.

Background ultraviolet (UV) refers to the electromagnetic spectrum in the wavelength from (10 nm ~ 400 nm) radiation, the wavelength between visible light and X-ray, for the naked eye is not visible.

In 1801, German physicist Ritter discovered that the ultraviolet ray was found in a section outside the ultraviolet end of the sunlight spectrum, which could sensitize the photographic negative containing silver bromide. Ultraviolet rays can be used to sterilize bacteria, but excessive ultraviolet rays entering the body can cause diseases such as skin cancer and cataracts.

Ultraviolet rays can be divided into four regions according to different wavelengths: uva for short, with the wavelength of 320nm ~ 400nm; Ultraviolet B (UVB) is short for UVB, the wavelength is 280 nm ~ 320 nm; Short wave ultraviolet (UVC) is short for UVC, the wavelength is 200 nm ~ 280 nm; Vacuum ultraviolet (UVD) is abbreviated as UVD, with the wavelength of 100 ~ 200 nm.

Among them, long wave ultraviolet (UVA) is far more penetrating than medium wave ultraviolet (UVA) on clothing and human skin. It can reach the depth of dermis and act on melanin in the epidermis, thus causing skin melanin deposition and blackening. Therefore, UVA is also known as "long wave black spot effect ultraviolet".

Most of ultraviolet B (UVB) is absorbed by the skin epidermis and cannot penetrate into the skin. However, due to its high energy, it can cause strong light damage to the skin, and the dermal blood vessels of the irradiated area will expand, and the skin may have symptoms such as redness, swelling and blisters, so it is also known as "UVB with medium wave erythema effect".

Short wave ultraviolet (UVC) has the function of disinfection and sterilization, also known as "C-band ultraviolet" or "short wave sterilization ultraviolet". Its penetration ability is the weakest, unable to penetrate most of the transparent glass and plastic. The short wave ultraviolet rays contained in sunlight are almost completely absorbed by the ozone layer. Short wave ultraviolet radiation is very harmful to human body. Short time irradiation can burn skin, and long-term or high-intensity irradiation can also cause skin cancer or cataract and other diseases.

Ultraviolet germicidal lamp gives off UVC. Traditional short wave sterilization ultraviolet (254nm) can be used to disinfect empty wards or empty subway cars. However, direct exposure to these traditional ultraviolet lights is not possible in manned spaces, as it may be harmful to health.

Recently, the Irvine Medical Center of Columbia University has adopted a human safe "far UVC", which can kill more than 99.9% of seasonal coronaviruses found in air droplets.

The lead author of the study, a professor at Columbia University's School of vagal medicine and surgery According to David Brenner, director of the University of Columbia's Center for radiation medicine, Dr. David Irvine, director of the center for indoor air disinfection at Columbia University, said: "there may be a significant reduction in the level of indoor transmission of the virus through the monitoring of the human air environment by Dr. David Brenner

The paper for the study was published in the journal scientific reports on June 24.

What is far UVC? It is a part of UVC and its wavelength range is 207nm ~ 222nm. It can penetrate the genetic material of microorganism and destroy the bond of genetic material to prevent its replication, thus disinfecting the object and air. However, it can not penetrate the tear layer of the eye or the dead cell layer outside the skin, and can not reach or damage the living cells in the body, so it will not cause skin cancer or cataract. In short, it's safe for humans, but it can kill bacteria.

In previous studies, researchers have shown that C-band ultraviolet radiation can safely kill airborne influenza viruses. The new paper extends their previous work to seasonal coronaviruses, which are structurally similar to the novel coronavirus (sars-cov-2), which causes covid-19.

In this study, researchers used a spray device to aerosol gel two common coronaviruses. Then, the coronavirus contained in the aerosol flows through the air in front of the C-band far ultraviolet lamp. After the aerosol was exposed to C-band ultraviolet radiation, the researchers tested to see how many viruses were still alive.

The device is used to test the efficacy of C-band ultraviolet rays in killing airborne coronavirus.

The researchers found that more than 99.9% of the virus exposed was killed by very low doses of C-band ultraviolet radiation. Based on these findings, the researchers estimate that under the current regulatory limits, continuous exposure to far ultraviolet light will kill 90% of airborne viruses in about 8 minutes, 95% in 11 minutes, 99% in 16 minutes and 99.9% in 25 minutes.

The sensitivity of coronavirus to far ultraviolet radiation shows that it is feasible and safe to use the far ultraviolet lamp on the head in indoor public places with people, which can significantly reduce the risk of human to human transmission of coronavirus and influenza virus.

In another ongoing study, the researchers tested the effectiveness of C-band ultraviolet radiation on a new airborne coronavirus. Preliminary data show that far ultraviolet lamp is also effective in killing new coronavirus.

Brenner says: "Far ultraviolet rays can't tell the type of coronavirus, so we expect it to kill the new coronavirus in the same way. Because the new type of coronavirus is mainly transmitted by droplets and aerosols formed in the air by coughing and sneezing, it is very important to have a tool that can safely inactivate the coronavirus in the air, especially when there are people nearby."

Brenner continued: "Because it can be safely used in manned spaces such as hospitals, buses, airplanes, trains, railway stations, schools, restaurants, offices, theatres, gyms, and any indoor place where people can gather, C-band ultraviolet radiation can be used in conjunction with other measures, such as wearing masks or washing hands, to limit the spread of the new coronavirus and other viruses."