Sani UV-C and its Application in Air Handling Units for MDR-TB prevention

By Edward Erasmus | 20 Mar, 2017

People are spending more time indoors than ever before. Older buildings are accommodating more employees than they were designed for and consequently Indoor Air Quality has become a serious health topic. It has been proven that the air we breathe can make us feel unhealthy and lethargic. The air that we breathe can aggravate allergies and induce illnesses. IAQ can be affected by microbial contaminants (mould, bacteria), gases (including carbon monoxide, radon and volatile organic compounds) that can induce adverse health conditions. Indoor air is becoming an increasingly more concerning health hazard than outdoor air. Using ventilation, filtration and source control are the primary methods for improving indoor air quality in most buildings. Unfortunately most air handling systems create ideal environments for microbial contaminants to grow and propagate. The warmth and moisture found in the Heating, Ventilation and Air Conditioning systems of households and office buildings make the perfect breeding ground for airborne moulds, microorganisms and bacteria. These HVAC systems also provide an ideal way to circulate viruses and germs around an entire office building or home in a relatively short time.The use of Ultra Violet in air handling units has become an efficient solution in de-activating Mould, Mildew, Bacteria and Viruses.

The bactericidal effects of ultra violet radiation were investigated in the 19th century. In the early 1940’s William F Wells and colleagues demonstrated the ability of ultra violet germicidal irradiation (UVGI) which is now called germicidal ultra violet (GUV)to prevent the spread of airborne infections. Ultra Violet light had generally been used to disinfect surfaces, water and other liquids. Germicidal disinfection is delivered at the 254 nanometre wavelength in the light spectrum and is known as UV-C. Ultra violet radiation deactivates microorganisms by penetrating the cell wall and disrupting the DNA structure thereby rendering them unable to infect or reproduce. Continuous dosages over time will result in death of the organism. The general rule of thumb is intensity (of the UV light) over time (the amount of time the organism is exposed to the rays), much like one running ones finger over a flame; if it’s done too fast nothing will happen but if you run it over slowly you will get burnt. Ultra Violet Germicidal Irradiation is effective in deactivating microbial agents such as Influenza A virus, Bacteria such as Mycobacterium tuberculosis, Legionella pneumophila and Fungi, including Aspergillus niger spores, Rhizopus nigricans spores and Listeria monocytogenes. The list is long but these are some of the more common microbiological agents. All microbiological agents are susceptible to Ultra Violet rays.

To determine the ultra violet needs for an HVAC system one needs to know the sanitary requirements and the velocity of the airflow through the system. Based on this factor GUV units can be supplied with single or multiple lamps and varying wattages. Many GUV units consist of an extruded aluminium framework with multiple lamps that are installed inside the HVAC unit. Installation of GUV units is most effective when the ultraviolet radiation shines on the cold air side (wet side) of the air conditioner evaporator coil. This keeps the evaporator coil clean by reducing the normal mould and algae growths that can act as an incubation area for bacteria. This also prevents the accumulation of mould and fungi on the coil and filters that can inhibit air flow and thus increase electricity and cooling costs.
Most HVAC systems in South Africa are not installed with GUV units and therefore there is no standard GUV unit. In most instances UV-C units need to be custom manufactured to the specifications of the air handling unit. Often there is no room for a lamp framework or there is limited access to the air-conditioning system. In situations like this an ‘external unit’ is fabricated where the ballast and starter are housed in a base that is mounted to the side of the filter block with the lamp(s) extending inside.
In other situations a complete ‘stand-alone’ unit can be manufactured and placed directly into the duct or ducts. These in-duct and on-coil fixtures can be mounted in various configurations for optimum pass-by air decontamination, and/or to irradiate cooling coils and drain pans.

The probes (UV-C lamps) should be wiped clean once per year. Depending on the manufacturer of the lamps replacement should be once every two years, usually the first quarter of the third year. A UV-C lamps output generally deteriorates about 12% to 15% per year, and the UV-C output after two years is about 67% of a new lamp.
Exposure to the germicidal wavelengths of UV light can cause sunburn and can produce extremely painful inflammation of the cornea and damage to the retina. Prolonged exposure can cause blindness. Maintenance schedules are one of the most important factors in using UV-C or GUV units for prevention.

For more inforamtion on Sani UV-C units please do visit or contact me at

011 462 5525
South Africa



Danila Brindak Replied at 12:35 PM, 20 Mar 2017

It is advertisement of portable room air cleaners at the IC TB forum. It is a bad idea.

Edward Erasmus Replied at 1:36 AM, 22 Mar 2017

Hi Danila

Hope you are well. Here in South Africa there is very little awareness on UV-C products and its benefit in reducing person to person infection in overpopulated areas.
As you are aware , TB is now a pandemic and UV-C does have its place in assisting with reducing TB. As a manufacturer it is important to have the correct testing done on all devices so that they are safe and effective.

Grigory Volchenkov, MD Replied at 8:11 AM, 23 Mar 2017

Absolutely agree with Danila: this looks more like commercial advertising.

For those colleagues who interested to learn evidence based information on UVGI for TB Infection control I recommend to join GHDonline TB IC community at Probably the only cost effective and feasible UVGI application for airborne infection control is Upper Room UVGI fixture, professionally designed and installed.

Room air cleaners (including with UVGI lamp inside) and ozone generating devices advertised in the attached files are not effective and may be in fact ussafe for room occupants. Also in these files there are serious errors in units and values of "doses required for deactivation".

Again I would like to welcome everybody interested to discuss and learn on TB transmission prevention in TB IC community.

Jaya Tyagi Replied at 8:41 AM, 23 Mar 2017

Does anyone have experience with use of Airocide air purifier in a TB
Laboratory. This technology is developed by NASA.

Edward Erasmus Replied at 5:44 AM, 24 Mar 2017

Hi Grigory

The devices shown above are proven to be effective by the NHLS of South Africa. There is no ozone producing units documented in the above mail and are all UV-C based. TB is now a pandemic in South Africa and we encourage awareness around improving IAQ to reduce person to person infection. There are guidelines to follow that ensures that GUV(not looked at as UVGI) is safe and is highly important and just so maintenance is of high importance. I believe we forget that UV-C ensures that pathogens do not multiply and if UV-C units have the correct efficacy they will be effective in their own way in reducing infection and even that of Superbugs.UV-C is not a cure but is there to assist with reducing infection within indoor overpopulated environments and awareness is of high importance.

Bekilizwe MSHANGA Replied at 6:54 AM, 24 Mar 2017

It appears that the GUV devices actually disinfect the air conditioning systems rather than the air in the room. In most African settings TB wards are ventilated by passive air or very basic fans. What would the applicability be for these lights as it has been highlighted that they are harmful to eyes?

Edward Erasmus Replied at 7:23 AM, 24 Mar 2017

Hi Bekilizwe

The UV-C lights are effective in HVAC units where as they keep the filters or cooling coils clean from any pathogens that can be growing on them. In cases where there is adequate fresh air mixing or ventilation there would be no need for UV-C. The areas that are to be focused on are areas with
Poor ventilation or air mixing
Closed windows
High occupancy or number of ill staff

Hospital acquired infections can be a serious concern and the UV-C is not a stand alone device but as it deactivates pathogens from reproducing or causing infection the time an infection remains inside a facility can be reduced as the microbial activity is reduced.

Looking directly at UV-C lights will cause severe arc eyes. UV-C units are enclosed to prevent the Invisible light been emitted and Upper room GUV or UVGI units emit a beam in the upper section of an area at a height that should be able to make contact with the open eye.

Edward Erasmus Replied at 7:44 AM, 24 Mar 2017

Hi Bekilizwe

Just to correct a Typing error.
Looking directly at UV-C lights will cause severe arc eyes. UV-C units are enclosed to prevent the Invisible light been emitted and Upper room GUV or UVGI units emit a beam in the upper section of an area at a height that should not be able to make contact with the open eye.