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The standard for air-cleansing in healthcare facilities is filtration.¹ Basically it works by bringing outdoor air into the system, where it meets with a low-efficiency filter, which removes large particulate matter and many microorganisms. The air then enters the distribution system where it’s conditioned to appropriate temperature and humidity levels. Then it passes through an additional bank of filters for further cleaning before being delivered to each zone of the building. After distribution, the air is withdrawn through a return duct system and sent back to the HVAC unit. Some of the "returned" air is exhausted to the outside; the remainder is mixed with outdoor air for dilution and filtered for removal of contaminants. Air from "soiled" areas has particular exhaust needs. For example, toilet-room air usually is exhausted directly to the atmosphere through a separate duct exhaust system, and air from the rooms of tuberculosis patients is exhausted to the outside, if possible, or passed through a high-efficiency particulate air (HEPA) filter before recirculation.¹

There are five methods of filtration, with varying levels of efficiency: 1) straining (low filter efficiency), which removes large particles; 2) impingement (low efficiency), in which particles collide with the fibers of the filter and stick, sometimes with aid of adhesives; 3) interception (medium efficiency), where particles become entrapped in the filter and attached to its fibers; 4) diffusion (high efficiency), where small particles moving erratically collide with and remain attached to filter fibers; and 5) electrostatic (high efficiency), in which negatively charged particles are attracted to positively charged filter fibers.¹

David M. Shagott, president, Abatement Technologies Inc, Suwanee, GA, offered good advice on features and functions purchasers should look for in a good air-cleansing system. "I’d include filtration efficiency; airflow; functionality in the healthcare environment; safety and security features; ease of use; mobility, if the device must be moved from area to area; manufacturer experience and expertise; and product approvals. Too many of the devices sold to healthcare facilities are simply general-purpose air cleaners re-positioned as medical devices. The potential risks require much more."

Yes, indeed, when examining air-cleansing systems, it’s important to investigate whether the system is appropriate for use in a healthcare facility and whether vendors can back up the claims made for their products. Regulatory and advisory agencies such as the CDC, American Institute of Architects, the Environmental Protection Agency (EPA), the Food and Drug Administration (FDA), and the Joint Commission are several of the agencies whose guidelines should be consulted by wise purchasers to educate themselves as to whether the product they’re considering acquiring meets standards.

Shagott highlighted the importance of meeting standards set by leading regulatory and advisory agencies. "Abatement Technologies systems are tested and certified by Intertek Testing Services to the Occupational Safety and Health Administration, United Laboratories, Canadian Standards Association, and National Electrical Code safety standards, and have FDA 510C clearance as class II medical devices. Many states selected them as their prime or sole means to meet Health Resources and Services Administration Critical Benchmark 2.2, and several major hospital buying groups have selected Abatement as their sole or prime vendor for HEPA devices."

He described specifically how Abatement Technologies’ air-cleansing systems meet the needs of their customers: "Abatement Technologies makes two types of main healthcare filtration devices: HEPA-CARE systems, used for negative-pressure isolation of infectious patients, positive-pressure protective isolation, or continuous air cleansing in other areas with high infection risks; and HEPA-AIRE (stainless-steel cabinets) and Predator (rotational-molded polyethylene cabinets) portable air scrubbers, used to meet infection control risk-assessment requirements for isolating particulates released into the air during indoor construction and maintenance activities."

Many companies offer HEPA filtration devices, so it pays to do a little investigative work. Biosense Inc., San Jose, CA, for example, offers the Recirculator II, which they bill as smallest, quietest, lowest cost portable solution for airborne threats in the country. IQAir, Santa Fe Springs, CA, offers low-maintenance, in-duct air cleaners with HyperHEPA technology, which they claim are up to 100 times more effective in removing allergens, bacteria, viruses, and dust than in-duct filter systems. It’s said to be quiet and invisible because it’s installed in existing HVAC ductwork. IQAir also touts ultra-low pressure drop technology, which allows air to pass through the filter more easily than with other in-duct air filters. To see a video of how it works, go to http://www.iqair.us/commercial/hvacair cleaners.

More isn’t always better, but cleansing the air in healthcare facilities is one of those cases where it could be. There are certain measures that can be used to augment the work of filters in decontaminating the air. One of those methods is ultraviolet (UV) germicidal irradiation (GI); however, the CDC cautions that, whereas UVGI can be used as an adjunct air-cleaning measure, it cannot replace HEPA filtration. "As a supplemental air-cleaning measure, UVGI is effective in reducing the transmission of airborne bacterial and viral infections in hospitals, military housing, and classrooms, but it has only a minimal inactivating effect on fungal spores. UVGI is also used in air handling units to prevent or limit the growth of vegetative bacteria and fungi."¹

Steril-Aire Inc., Burbank, CA, "manufactures a line of multi-patented ‘UVC Emitters’ that use ultraviolet-C (UVC) energy, the most germicidal wavelength in the UV spectrum, to kill or deactivate microbial contaminants," Robert Scheir, president, told Healthcare Purchasing News. "Installed in a hospital air-handling system, this UVC energy can destroy 90% to 99% of infectious microbes, depending on the number of air changes per hour, reducing them to a level far below what it takes to infect most patients and staff. UVC has the ability to improve indoor air quality and reduce nosocomial infections. It works against all strains of influenza; other viruses including colds, SARS, measles, and German measles; and bacteria including tuberculosis, Legionella, pneumonia, and whooping cough. It also kills mold and organic growth in the air-conditioning coils, allowing air handlers to return to peak operating efficiency for energy savings."

Scheir also highlighted the importance of seeking out air-cleansing products that meet standards and suggested checking out Steril-Aire’s claims: "The EPA, in conjunction with the U.S. Department of Homeland Security, has released test reports on several leading brands of UVC devices. In these tests, the Steril-Aire UVC Emitter achieved 99.96% destruction in a single pass on airborne bacteria, 99% on viruses, and 96% on spores. It also achieved the highest "dose-per-watt" of any product tested. The full reports are useful for comparing the different devices and may be accessed at http://www.epa.gov/nhsrc/
news/news 062606.html. In addition, Steril-Aire has both utility data and anecdotal reports from hospitals showing 15% to 29% reductions in HVAC energy costs since adopting UVC, as well as anecdotal reports indicating significant reductions in nosocomial rates where Steril-Aire UVC is installed."

"Because of the many benefits of UVC, we are confident these devices will someday be found in every healthcare facility, as well as in every air-conditioned school, commercial and industrial building, and home," said Scheir.

Zentox Corporation, Newport News, VA, also offers an air purifier employing UV light, the Photox system. Robert Kim, Photox business manager, recommended that purchasers look for a complete system, one that removes dirt, chemical vapors, and odors. "The Photox series is an advanced indoor air -purification system based on photocatalytic oxidation technology. It traps particulates; breaks down vapors commonly found in healthcare facilities, such as odors from urine, feces, and wounds, as well as odors such as formaldehyde and alcohol, often found in laboratories within hospitals; and inactivates airborne contaminants including bacteria, viruses, and mold spores. The destruction of contaminants occurs inside the unit. It filters and oxidizes air at the same time, but does not produce ozone as some electronic air cleaners do."

Photox can be used in patient rooms, emergency rooms, operating rooms, laboratories, auditoriums, and reception areas, noted Kim. "The Photox system is portable, runs 24/7, is lightweight, and has a small footprint. The largest unit, Photox 500, weighs 45 pounds, measures 18" by 18" by 38", and purifies air over an area of 4,000 square feet. The Photox 100W is considerably smaller at 8 pounds and can be mounted on the wall in a patient room or can be placed on a table. It’s very quiet; it won’t interfere with the patient’s sleep."

Kim also emphasized the importance of meeting standards, noting that Photox is certified to be safe, meeting UL electrical safety standards. "Photox has been performance tested by EMSL Analytical Inc, laboratories. You don’t want an untried, unproven product."

STERIS Corporation (Mentor, OH)’s VaproSure Sterilizer is not an air-cleansing system per se, but it has an interesting relation to air cleansing. "The HEPA filter is an important part of an effective infection control program in that it can reduce the spread of airborne contaminants; it cannot, however, destroy antibiotic-resistant or other pathogens that may be present on the surfaces throughout a patient room. In this sense, the VaproSure Sterilizer can be complementary to HEPA filtration," said Matthew Mitchell, director of industrial decontamination solutions.

The VaproSure Sterilizer uses Vaprox Sterilant, an EPA- registered (#58779-4) sterilant for the sterilization of all exposed surfaces in hospital rooms. "The technology is recognized as a broad-spectrum sterilant, meaning it can destroy spores, bacteria, fungi, and viruses, like an autoclave," explained Mitchell.

The VaproSure Sterilizer is particularly applicable to outbreaks due to emerging and reemerging infectious diseases; "however," said Mitchell, "the VaproSure system can also be used prophylactically. It has been adopted in Europe in intensive-care units, operating rooms, patient rooms, burn units, and ambulances. It also has been used for over a decade in pharmaceutical, laboratory, and research applications to provide sterile environments."

Here’s how it works: The VaproSure Sterilizer is portable, so it can be placed inside or outside the patient room. If positioned outside the room, two holes will be needed: one for pumping the sterilant vapor in; one for pumping it out. The room is then sealed, the process is started remotely, and the automated four-step process begins: (1) dehumidification of the room to approximately 40%; (2) conditioning, which involves injection of the sterilant vapor to a target concentration; (3) sterilization; (4) and aeration of the room to break down the vapor into water vapor and oxygen. It’s an environmentally friendly, dry, non-condensing process, so it’s compatible with most electronics and sensitive finishes.

Reduction of pathogenic organisms in the room may translate to lower infection rates. Even one infection can cost a hospital many thousands of dollars and much negative publicity, as the public grows ever more aware and knowledgeable about what’s transpiring behind hospital walls.

List price for the VaproSure Sterilizer, which includes training and certification, is in the $180,000 range. Consumable materials cost between $50 and $100 per use. When stacked against the cost saved by averting potential infections, the investment may be well worth the cost.

If you’re in the market for an air-cleansing system or for a product to augment the system you have, do your homework. Most importantly, familiarize yourself with industry standards and investigate whether products can live up to their claims.

Reference

1. Sehulster L, Chinn RYW. Guidelines for environmental infection control in health-care facilities. Recommendations of the CDC and the Healthcare Infection Control Practices Advisory Committee, 2003. www.cdc.gov/ncidod/hip/environ/guide.htm

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