UVC can neutralize airborne pathogens without removing them. A decades-old technology could offer a way other than air purification or vaccination to make indoor spaces safer.
A decades-old technology could be finding a new role in the fight against airborne infections. Photo: Getty Images
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It is common knowledge that airing out a building is important. Ventilation replaces contaminated indoor air with fresh air from outside, while filters capture particles as air passes through them.
But there is another possibility: instead of removing airborne viruses and bacteria, light could be used to render them harmless while they are still in the room.
Different wavelengths of light have very different biological effects. Blue-enriched light in the evening, for example, can suppress melatonin and disrupt the body's circadian rhythm, while prolonged screen use can contribute to digital eye strain. Modern LED lightbulbs also differ significantly in their spectral output from candles and traditional incandescent bulbs.
Move beyond visible violet light along the electromagnetic spectrum and you reach ultraviolet radiation. Certain UV wavelengths can damage the genetic material of microorganisms, an effect that has long been exploited for disinfection.
The question is whether that same effect can be used safely in rooms occupied by people.
Ultraviolet light is broadly divided into UVA, UVB and UVC. It is UVC that is particularly interesting for disinfection.
Conventional germicidal systems typically use UVC light at around 254 nm, a wavelength capable of inactivating microorganisms by damaging their DNA or RNA.
Unlike an air purifier, UVC does not necessarily remove a virus or bacterium from the room. Instead, a sufficient dose damages its DNA or RNA so that it can no longer replicate. The particle may still be physically present in the air, but it has effectively been deprived of what makes it infectious.
Using conventional UVC around people presents an obvious safety problem.
The traditional solution is surprisingly simple. UVC fixtures are mounted high on walls or ceilings and shielded so that their radiation is directed across the upper part of the room rather than at the people below. Air circulation carries airborne microorganisms into this irradiated zone, where susceptible pathogens are inactivated before the air circulates back toward the occupants.
In effect, the upper part of the room becomes an invisible disinfection chamber.
The technology predates Covid by decades and has been studied extensively as a means of reducing the airborne transmission of tuberculosis. CDC research has found that appropriately designed upper-room germicidal UV systems can inactivate airborne tuberculosis bacteria while keeping exposure in the occupied part of the room within safety limits.
A wall-mounted UVC lamp designed to inactivate airborne pathogens. Photo: Aerolamp
Cleaning Air Without Replacing It
The potential becomes particularly interesting when UVC is compared with ventilation.
Indoor air quality is often measured in air changes per hour, or ACH: how many times a volume equivalent to the air in a room is replaced or cleaned every hour. Increasing that figure conventionally means moving and potentially heating or cooling increasingly large quantities of air.
UVC takes a different approach. Its performance can be expressed in equivalent air changes per hour: the amount of conventional clean-air ventilation that would be required to achieve a comparable reduction in viable airborne microorganisms.
In one full-scale experiment, an upper-room UV system produced an inactivation rate equivalent to around 16 additional air changes per hour.
That does not mean every UVC installation will achieve the same result. Performance depends on the pathogen, UV dose, humidity, room geometry and, crucially, how effectively air circulates through the irradiated zone.
Conventional UVC can also damage the eyes and skin at sufficient exposure levels, while poorly positioned fixtures or inadequate airflow can undermine effectiveness. Installation therefore requires more engineering than simply mounting a UV lamp on a wall.
UVC is consequently better understood as a complement to ventilation rather than a replacement for it. Ventilation also removes carbon dioxide, odors and pollutants that ultraviolet light cannot eliminate.
But if UVC can provide substantial additional infection control without requiring the same increase in outdoor airflow, the implications could extend beyond health.
Respiratory infections impose substantial costs through absenteeism and reduced productivity.
In Germany, sickness absence resulted in an estimated €134bn ($156bn) in lost production and €227bn ($265bn) in lost gross value added in 2024. Those figures cover all illnesses, not respiratory infections alone.
In the UK, a 2024 Office of Health Economics study estimated that short-term respiratory infections cost businesses £44bn ($60bn) annually through sick leave and reduced productivity. The research was commissioned and funded by pharmaceutical company Pfizer.
The potential economic case for UVC therefore rests on two questions: whether it can meaningfully reduce infections in real-world settings and whether doing so is cheaper than achieving similar protection by moving and conditioning more air. A new firm called Aerolamp now offers the lamps at a price of €439 ($509) each. With several units and mounts, a complete office can be covered. The company says that if the technology is more widely adopted, it will become more affordable. It could become as commonplace in homes as air conditioning.
Larger companies such as Philips already offer UVC light bulbs separately without mounts at more affordable prices.
The technology is unlikely to fully replace ventilation, filtration, vaccination or other infection-control measures. But it points toward a change in how respiratory disease can be approached and how its spread can be minimized.
Modern buildings already use engineering systems to control temperature, humidity, smoke and air quality. Airborne pathogens could increasingly be treated as another feature of the indoor environment that can, at least partly, be engineered.
The science behind upper-room UVC is decades old. The more important question now is whether the economics and real-world evidence are strong enough to bring it into more of the buildings where people spend their lives.
