South Korean researchers have developed a portable virus killer that uses ultraviolet rays to take out COVID-19 in a second, the Korea Railroad Research Institute said Monday.

According to the KRRI, the newly developed anti-virus equipment weighs 1.8 kilograms, making it easy for workers to carry it around public transportation such as subways and trains.

As the UV ray-using virus killer does not have a risk of fire or leave residue, the KRRI said it can be used for disinfection work in places where it is difficult to use the traditional liquid-type disinfectant.

The researchers at KR Biotech’s disease control lab tested the efficacy of the virus killer and found that 99.9 percent or more of COVID-19 was gone within one second of irradiating the UV rays.

“We will expand our research and development so that the newly developed technology can be applied in indoor public facilities through a fixed model on the ceiling and an installation on (robots),” said an official at the KRRI.