Disinfecting the Air We Breathe with UV-C Light

Until only a few months ago, the perceived wisdom was that SARS-CoV-2 spread by respiratory droplets expelled from the mouth. The droplets then fall to the ground contaminating surfaces and people in close contact with each other. It was widely believed that the virus made its way to our hands, then our noses, eyes, or mouths. Hence the need to regularly wash our hands and to avoid touching our face or mask and the requirement for social distancing. in 2020, advice from the World Health Organization focused on heavier, short-range droplets being the main culprit. The need to ventilate rooms and the importance of airflow seemed to be secondary considerations at best.

Thankfully, we now know that aerosol particles represent a primary route for the transmission of the SARS-CoV-2 virus. Both the World Health Organization and US Centers for Disease Control and Prevention (US CDC) have confirmed research findings and recently updated their guidance. This is because the virus can literally float through the air and be breathed in. Good ventilation and “clean air” are therefore essential, as are ways to disinfect the air.

Air disinfection is doubly important given the first tentative steps being taken to open up schools, shops, restaurants, gyms, and indoor events. Opening windows to reduce pathogens does help and typically it may result in one air change per hour. According to research, this can remove around 63% of pathogens from a room in one hour. Yet such ventilation falls far short of effective disinfection, which may require removal of 99.99% of pathogens, and is not always feasible or possible, particularly inside modern office blocks. One technology attracting a lot of interest is ultraviolet C (UV-C) lamps and luminaires. This technology is already being used inside ventilation and air conditioning systems and for a host of disinfection applications for air, surfaces and water. At the wavelength of 254 nanometers, UV-C light can inactivate viruses, bacteria, and mold by breaking down their DNA and RNA, rendering them harmless. Small UV-C disinfection lamps inside heating, ventilation and air-conditioning units prevent the build-up of microorganisms and film on critical components such as on the evaporator coils. Disinfection of the coil makes these units more efficient, therefore saving electricity, while lowering maintenance costs. Generally speaking, the more air changes per hour the better. Offices should really seek the equivalent of 15 to 20 air changes per hour – which is roughly the same as a commercial passenger jet.

And it can be done easily: the equivalent to 20 air changes per hour and higher can be achieved by UV-C disinfection upper air luminaires. Equipped with shielding and attached high enough on a wall or ceiling (in accordance with applicable safety standards), so as to avoid direct exposure to people or animals, these silent, unobtrusive systems create a zone of UV-C energy that disinfects the air in a highly efficient and fast manner, leveraging the natural convection of air in a room. As UV-C light is a powerful disinfectant, it is important that people, animals, and plants are not directly exposed to the light source as it can harm their skin and eyes and can damage the leaves of plants. Below, people can literally go about their daily business as the air above them is disinfected.

The effectiveness of UV-C disinfection upper air systems against the SARS-CoV-2 virus is not in dispute. Tests performed with Innovative Bioanalysis in a Certified Safety Reference Laboratory in Costa Mesa, California, found that Philips UV-C disinfection upper air luminaires inactivated 99.99% of SARS-CoV-2 in the air of a room within 10 minutes, and the virus was below detectable levels at 20 minutes.

It is important to note that tests were conducted with Philips UV-C disinfection upper air wall mounted luminaires. The overall dimensions of the test chamber were approximately 8’x8’x10’, compliant with Biosafety Level 3 standards. According to results obtained from a laboratory test conducted by Innovative Bioanalysis, a CAP, CLIA, AABB Certified Safety Reference Laboratory, in a room with sufficient air circulation. The test was performed with artificial ventilation in the form of fans.

Given the results, it’s hardly surprising that the technology is being rolled out across the world and can now be found inside public spaces such as supermarkets, gyms, bars and offices, and even in the dressing rooms of top-flight soccer clubs such as RB Leipzig and PSV Eindhoven.

Again, UV-C disinfection technology offers more than a glimmer of hope as it has an enviable track record against all pathogens tested in laboratories to-date.

Vaccinations, handwashing, masks, and chemical disinfectants all continue to play their part. Now that we know that aerosols are a key form of transmission, we have in UV-C upper air disinfection a guiding light towards the end of the tunnel.

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