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A brief history of UV light in health and medicine

A brief history of UV light and HEPA in science, health & medicine



UV irradiative light was discovered in 1801 when the German physicist Johann Wilhelm Ritter observed that invisible rays just beyond the violet end of the visible spectrum darkened silver chloride-soaked paper more quickly than violet light itself. He called them deoxidizing rays to emphasize chemical reactivity and to distinguish them from heat rays, discovered the previous year at the other end of the visible spectrum. The simpler term chemical rays were adopted soon afterward, and remained popular throughout the 19th century.



Arthur Downes and Thomas Blunt published a paper describing the sterilisation of bacteria exposed to short-wavelength light. UV has been a known mutagen at the cellular level for over 100 years.



The Nobel Prize for Medicine was awarded to Niels Finsen for his use of UV against lupus vulgaris, tuberculosis on the skin.



UV-C was first used to disinfect the municipal water supply of Marseille, France.

Hospital Service


Westinghouse developed the first commercial UV-C germicidal lamps. They were used primarily in hospitals. World War II, UV-C was used for sterilising air in hospitals, kitchens, meat storage and processing plants, bakeries, breweries, dairies, beverage production, pharmaceutical plants and animal labs – anywhere microbiological contamination was a concern.

One of our UV partners was established in 1939 by a past employee of Westinghouse, now it is the oldest manufacturer and developer of UV based devices in the world.

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HEPA filter technology developed in the 1940s by the US Army Chemical Corps and National Defense Research Committee. As part of the Manhattan Project, scientists were required to create a filter suitable for removing invisible radioactive materials from the air. This is why the filter size was set at 0.3 microns back then and still is certified to that size today.



UV-C was incorporated into air handling equipment. It became a significant component in the control and eradication of tuberculosis. The first UV based devices with up to four UV-C light bulbs were installed in rooms with high numbers of infected people. These “Upper Room Devices” were not only safely deployed, but they were also highly successful quashing infection from this deadly airborne pathogen.


Since the 1950s, HEPA Filter use has expanded beyond the nuclear sector to include mould remediation, asbestos clean-up, lead cleaning, chemical cleaning, home air filters, office filters, laboratories, operating theatres, medicine manufacture and clean rooms.



During the 1960s, public awareness of microorganisms increased as new drugs and sterilising cleaners became available. But increasing popularity in mechanical ventilation reduces the demand for UV-C air disinfection systems.


1970s & 80s

With significant developments in UV-C disinfection technology and concerns over the excess use of chemical disinfection, UV-C technology regains popularity among organisations requiring a high level of hygiene.



UV-C was first used for large scale water treatment processing for municipal systems as well as for treatment of swimming pools. The first use of UV-C within HVAC systems was also pioneered in 1996, proving to be effective in the elimination of vaccine and antibiotic resistant “super-bugs” in hospitals.

In 1994, PP-L founder and chartered engineer, Paul Waldeck founded a consultancy specialising in designing safety critical environments in pharmaceuticals, biosciences, food manufacture, laboratories, nuclear, and rail.

Person In Hazmat Suit


Over 20+ years, Paul Waldeck built his consultancy to be a global technology leader in hygiene critical sectors as well as supporting organisations in conventional built environments such as offices, hotels, residential, ports, airports, logistics and manufacturing.

During the SARS pandemic of 2003, our UV-C products were successfully deployed to hospitals to reduce transmission risk. These disinfection systems proved effective, helping to protect high risk settings.

Present Disinfectant Technology Advancements - Graphic


Recent technological advancements have made it possible for UV-C disinfection technology to be deployed in an ever-expanding field of applications in conventional environments, including the disinfection of water, air and surfaces.


The challenges of a low carbon economy and global sustainability targets for emissions have driven the mechanical ventilation industry to design for lower ventilation rates, lower filter ratings, and more recirculated air with temperature recovery (heat & cooling). This is not conducive for Pandemic Resilience and now the Built Environment is in serious trouble because of the airborne virus that causes Covid-19.


HEPA Filters in mechanical systems are the domain of specialist safety-critical environments only because they cannot be practicably used or retrofitted in conventional buildings to filter out pathogens without enormous expense and carbon footprint. But recent years have seen the rise in portable HEPA devices which are effective for local source control.


With the escalation of the COVID-19 pandemic since 2019, the importance of aerosol transmission has meant ventilation and air cleaning have come to the fore to mitigate infection. Scientific studies demonstrate the effectiveness of UV-C in COVID-19 disinfection, both on surfaces and in the air, whilst being energy efficient too.


In May 2020, PP-L was fast-tracked onto the UK Government Coronavirus (Covid-19) Response List of Key Suppliers under the Medical Category, managed by The Crown Commercial Service (CCS).


In June 2021 PP-L were successful in a commercial process, becoming an Approved Supplier to the NHS and the Public Sector under the new call-off for “Air Purification & Decontamination”.