Covid-19 virus will be completely inactivated after being irradiated by UV-C ultraviolet rays at a certain dose for several seconds.

Research by the National Laboratory for Emerging Infectious Diseases at Boston University shows that UV-C ultraviolet light source can inactivate Covid-19 virus. This discovery is expected to promote the development of a series of products that can stop the spread of Covid-19 pandemic, and it will provide inspiration for related Chinese enterprises and R&D institutions.

Ultraviolet light is usually divided into UV-A (wavelength of 315-400 nm), UV-B (wavelength of 280-315 nm) and UV-C (wavelength of 200-280 nm). Among them, UV-C ultraviolet ray has the shortest wavelength and the highest energy, so it can destroy the DNA and RNA of bacteria, viruses and other microorganisms in a short time so as to prevent their reproduction and replication. Therefore, UV-C ultraviolet ray is often used in microbial disinfection and biochemical analysis. UV-C ultraviolet ray has high-efficiency and broad-spectrum effect, so it can disinfect water, air and object surfaces very quickly. Experimental data show that UV-C ultraviolet ray with an irradiation intensity of 30 mW per square centimeter can kill nearly 100% of most bacteria in only one second, so it is widely used in medical and health fields.

So, how is the effect of ultraviolet rays of this wavelength disinfecting Covid-19 virus? After the outbreak of the pandemic in the United States, Anthony Griffith, an associate professor of medical microbiology at Boston University, led a team to develop equipment to stop the spread of the virus. It is worth mentioning that the American National Laboratory for Emerging Infectious Diseases, where the team works, is one of the most advanced laboratories in the world, with laboratories at biosafety level four (P4), level three (P3) and level two (P2).

In the research, they used UV-C ultraviolet light source to explore the capability of different doses of UV-C ultraviolet radiation to inactivate viruses on the surface of research materials. The team used a radiation dose of 5 mJ per square centimeter for 6 seconds, which inactivated 99% of the viruses. Based on this result, they inferred that 99.9999% of Covid-19 virus could be inactivated if the radiation dose reached 22 mJ per square centimeter and the radiation time reached 25 seconds.

"The experimental results show that the virus will be completely inactivated after being irradiated by UV-C ultraviolet rays above a certain dose for several seconds." Dr. Griffith said, "We are very excited about this discovery and hope to accelerate the research and development of related products to stop the spread of Covid-19 virus."

Boston University has proved that ultraviolet light source products can inhibit the spread of Covid-19 virus so as to make enterprises and factories safer. Professor Chen Jianbo, director of the Department of Building Environment and Energy Engineering, University of Shanghai for Science and Technology, said that if conditions permitted, people could install "UV+Photocatalyst" equipment in air-conditioning boxes, which had a strong ability to kill influenza virus. This kind of product has been rather mature in today’s market, but it is worth mentioning that if ultraviolet lamp is only installed in air-conditioning boxes, it will not be effective enough at killing viruses in the air.