UV Applications in Hospitals

Utilizing Germicidal UV Technology to Inhibit Microbial Growth and Limit Transfer of Infections in Hospitals

UVC can be utilized to inhibit microbial growth and transfer in hospitals through installation in HVAC systems and stand-alone fixtures as follows:

1. Cooling Coil disinfection – installation of UVC fixtures for direct irradiation of the cooling coils
2. Air disinfection – installation of in-duct UVC air cleaners for air stream irradiation; additional in-room UVC fixtures can be used for upper air disinfection
3. Surface Sterilization with direct UVC fixtures
4. UVC for Operating Rooms – a unique combination of air and surface sterilization systems specifically designed for Operating Rooms
5. Mobile UVC Room Sterilizers – used in unoccupied rooms where installation of permanent fixtures is not practical.
   - Mobile UV System with 24 UVC lamps ARTZ
   - UV Mobile Room Sterilizer with 8 UVC Lamps
   - Mobile UV System with 4 High Output UVC Lamps

The primary difference in using UVC in air purification and surface sterilization is residence time - the amount of time the microorganisms are exposed to UVC radiation. In moving air streams germs are traveling at high speeds and therefore may be exposed for only a fraction of a second. Because of this, it is important to apply more UVC energy with High Output UVC lamps to get the disinfection desired.

With surface sterilization, there is an almost unlimited residence time therefore less UVC intensity is necessary. The dose needed for effective sterilization is a function of UVC intensity, time and distance from the surface.

Overhead UVGI at St. Francis Hospital

OR UVC sterilization is a specifically developed sterilization solution. Ensuring a sterile environment is very important for preventing complications during organ transplantation or open joint surgical procedures. Achieving and maintaining a sterile environment in operating rooms is crucial for patients with weak immune systems due to cancer or AIDS. Operating room UVC sterilization package compiles all implementations of the germicidal UV technology to ensure the required clean environment.

Operating Room UVC sterilization is achieved with two distinctive, although overlapping processes. First, before the operating room is occupied by people, it is entirely irradiated with direct UVC fixtures that sterilize all surfaces exposed to the UV rays. These fixtures must be turned off or turned down before personnel or patients enter the operating room. Second, the air of the operating room is irradiated with indirect germicidal fixtures to ensure sterile environment and stop the transfer of pathogenic or toxic microorganisms through air. The indirect fixtures stay on all the time. They either enclose the UV lamps or are equipped with louvers that direct the UV light to areas above eye level.

Germicidal UV door barriers are also utilized to prevent the harmful microorganisms from entering the sterile environment from outside of the operating room where the level of sterility is not as high.

Another possible entryway for the airborne microbes could be through the hospital HVAC system. This could be avoided with installation of UVC lights for air and surface sterilization in the hospital HVAC systems.

Direct surface UVC irradiation of the HVAC coils and dripping pans inhibits development of colony forming microorganisms. Air stream UVC irradiation sterilizes airborne germs such as bacteria, fungal particles, mold spores, and viruses.

A proper germicidal UVC light installation in the HVAC system will break the DNA of the microorganisms that reside in the ducts or circulate in the air-stream. Therefore as the indoor air circulates throughout the system virtually all airborne microorganisms will be rendered non-viable. The dead microbes cannot form new colonies but they still could be spread throughout the building. Since the dead microorganisms still represent a health hazard, it is strongly recommended that UVC is used in conjunction with HEPA filters. The HEPA filters capture particles smaller than one micron, i.e. the non-viable spores and bacteria would be captured and removed from indoor air. If only a HEPA filter is used without the UVC light, the filter itself will become a breeding ground for new colonies.

It has been proven that colony forming microorganisms will not grow or reproduce if they are directly irradiated with appropriate dosage of germicidal UV. As the indoor mold colonies grow they produce millions of spores that are blown through the HVAC ducts and distributed in the indoor environment. Once the spores are spread inside they just need food and water in order to start growing, reproducing and forming countless new colonies that release countless new spores. This is the mechanism of infesting the indoor environment of some contemporary airtight buildings with mold to such extent that it becomes impossible for people to live or work there. All this leads to lawsuits, big expenses for mold cleaning, huge losses and worst of all - health problems for many people. This could be avoided by installing specially designed germicidal UV fixtures that shine directly on the coils and drain pans. This is an effective solution for microbial growth inhibition.

The effectiveness of germicidal UV has been recognized by the U. S. General Services Administration Office of the Chief Architect and incorporated in the Facilities Standards for the Public Buildings as follows: "Ultraviolet light (C band) emitters/lamps shall be incorporated downstream of all cooling coils and above all drain pans to control airborne and surface microbial growth and transfer. Applied fixtures/lamps must be specifically manufactured for this purpose."

Germicidal UV light can be effectively utilized in hospitals and public buildings to inhibit microbial growth, spreading of infections and to increase indoor air quality. UVC can also help against mold problems by rendering airborne mold particles and mold spores non-viable and sterilizing surface mold colonies.

Main factors for the effectiveness of in-duct UVC systems intended to disinfect moving airstreams are UVC intensity at operating conditions, microbial susceptibility to UVC, duct wall reflectance and the cumulative effect of UVC on the microorganisms.

Given this information, UVC system designers can make educated performance estimates for the HVAC applications in hospitals. The results will provide measurable cost savings by:

1. Reduction in patient and staff medical expenses resulting from nosocomial infections, operating room infections, and aspergillosis
2. Reduction in routine maintenance costs for cleaning of ducts and coils
3. Improved efficiency of HVAC systems resulting in energy savings and extended life of the systems

The effect of UVC installed in HVAC systems can be further improved by utilizing of direct UVC lights for air and surface sterilization in waiting rooms, TB wards, operating rooms and laboratories. Portable and mobile UVC devises can be used as well.