Disinfection with Ultraviolet Light

Eliminating Mold and Pathogens with UV-C Technology

Use of UV-C light is gaining more acceptance as an effective method to disinfect mold and antibiotic-resistant microorganisms such as MRSA.

Throughout the world of healthcare there is a silent unseen killer to patients and medical staff. Called hospital-associated infections (HAI’s), these airborne pathogens present a serious challenge to infection-control professionals. The incidence of hospital-associated infections is a serious and widespread problem, with an estimated 1 in 10 patients acquiring an infection during a hospital stay. A recent report from the CDC stated that “hospital-acquired infection is a global problem and is the fourth greatest cause of mortality amongst Americans”. There are a whole range of potentially pathogenic microorganisms associated with nosocomial infections, many of which are opportunistic pathogens which are the frequent cause of respiratory infections. Hospitals, or other medical facilities are the ideal proving ground for airborne pathogens even with their close attention to the spread of infections. Infection can be spread in many ways, however, the most commonly encountered methods are direct contact and inhalation. Regular surface cleaning and hand-washing is one of the accepted ways to combat infection risks, although this only works if the medical staffs follows the policy. Although constantly wiping down medical equipment and hand washing is critically important, this doesn’t help to reduce the risks from inhalation of airborne microorganisms.


On average, a medical person, or hospital staff comes into a patient’s room every 15 minutes. Just the sheer number of times this happens in a 24 hour period opens the door for the potential of transmitting a microorganism from one place to another. Humans can fall prey to a whole range of viral and bacterial diseases such as measles and tuberculosis which are transmitted via the airborne route from one infectious individual to another susceptible victim. Infectious aerosols tend to be extremely small and can therefore remain suspended and sustainable in air streams over long periods of time. There are also many pathogens which can become airborne that exist within medical equipment, such as the ventilators, nebulizers, suction devices, etc. As a result the risk of airborne infections in high risk locations such as hospital and medical clinics, the risk is always high, especially for immunocompromised patients.

Attempts to control infections with drugs have just created more resistant strains. Out of the top six bacteria found within hospitals, each is resistant to at least one drug. The ineffectiveness of existing antibiotics is adding to more expensive drugs, and drugs which are becoming more resistant to treatment, so it becomes a vicious cycle.

UV-C Technology offers a Solution to Airborne Pathogens

Ultraviolet (UV) light occurs naturally in sunlight and UV rays from the sun are the best source of the vitamin D your body needs to ward off cancer and dozens of other health problems. But that’s just the beginning of what ultraviolet light can do, it can be extremely effective disinfectant with the ability to kill bacteria, viruses, and fungi (mold) in the air and on surfaces. The germicidal properties of UV light have been known since the 19th century. UV lamps were effectively used in the pre-antibiotic era extensively in tuberculosis (TB) wards to control the spread of infection, but with the development of anti-bacterial drugs UV air disinfection fell out of favor as the method of choice. However, in recent years, with the global rise in TB, MRSA, C-Diff which are becoming resistant to drug therapy there has been renewed interest in UV lamps for use as an infection control measure. Staphylococcus aureus or more importantly the methicillin resistant strain (MRSA) is a major problem in hospitals throughout the world. Although most outbreaks are associated with the a contact route for infection, the airborne route is thought to play an important role in particular locations such as intensive care and transplant wards, and burns units.

UV may be divided by wavelength into three bands, A, B, and C. Of these UVC is the shortest and most powerful. At the specific wavelength of 253.7 nm. It is proven to be deadly to viruses, bacteria and molds. UVC air sterilization is making a comeback as a proven and tested solution against airborne infections in healthcare. Many hospitals are already successfully reducing air-borne infection using some form of UV lamps. New types of UV technology will continue to be introduced to the market as the need for infection prevention increases due to drug-resistant strains of bacteria and viruses.

UV-C Germicidal Irradiation Equipment

Today UVGI (ultraviolet germicidal irradiation) is receiving renewed interest, given the emergence of new infectious diseases, pandemic strains of influenza and antibiotic strains of drug resistant pathogens.
With renewed interest in using UV technology new products are being introduced to the healthcare market. One of the most innovation and effective products combines treating air inside a special chamber as air passes through. Although, this is not unique, the system is unique in the way it’s mounted, which is recessed in the ceiling. This makes the unit, called the “Purealizer”, both unobtrusive and allows it to constantly “scrub” the air circulating in the area (or room) where it’s been installed.

The Purealizer is a patented-pending germicidal 2′ x 2′ troffer air disinfection system. The Purealizer uses UV light in the optimum germicidal range (254nm) combined with photocatalytic oxidation to disinfect an eliminate pathogens and volatile organic compounds (VOCs).

The fixture uses differential air pressure which passes through a highly reflective reaction chamber at 30 cfm to neutralize up to 99% of airborne pathogens in a first pass kill rate. The system is designed to easily mount to a t-grid in a 2’-ft. by 2’-ft. opening and operate continuously 24/7 to improve air quality.

A UV-C light tube has been engineered into a reflected array to produce an intense energy field capable of eradicating the 97% resistant microorganisms with a first pass kill rate. Slow airspeed coupled with a mathematically modeled chamber design ensures the air is maintained in close proximity to the radiation source. A MERV 6  filter, which is optional, helps filter all the larger particles prior to them entering the chamber which also helps to maintain the effectiveness of the UV light. The Purealizer UV fixture is designed to fit neatly in place of an existing 2 x 2 ceiling troffer. This means no additional space is taken up by the unit, and it would be hardly noticed by patients or even the staff. The 2′ x 2′ troffer can be easily mounted in patient rooms or critical care areas, which is at the source of hospital-associated infections.

The energy consumption is very low, under 50 watts and the system incorporates fans which are relatively quiet. The system is intended to be operated 24/7 days, which would provide continual air sterilization without the need for operator supervision. The system integrates the CDC’s 4 recommended hierarchies of defense to fight airborne infections, pressure, filtration, purification and dilution which is why it’s been proven effective to killing up to 99% of airborne pathogens.

The goal of 2′ x 2′ recessed UV troffer is to inactivate the infectious airborne microorganisms at the top of the room, or area, then supply the lower room with continuously disinfected air. Differential pressure using a set of fans carry airborne microorganisms through the UVC field which allows very large volumes of air to be serialized in a very short period. In a typical room the volume of air would have up to four (4) complete cycles of disinfection each hour. A key measure of the effectiveness of an air sterilization is the Purealizer’s ability to fully circulate all the air in the room, ensuring a uniform and continuous distribution.