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FAQs About Equipment for Infectious Patient Isolation

Frequently Asked Questions about Abatement Technologies® HEPA-CARE® Air Purification Systems for Meeting CDC Guidelines for Airborne Infection Control and HRSA Surge Capacity Planning

How much experience does Abatement Technologies have in the healthcare market?

Abatement Technologies has sold critical air filtration equipment to hospitals, clinics and other health-related facilities since the mid-1980s. We developed our first HEPA-CARE systems for infectious patient isolation rooms in 1992. Since then we have worked with more than 5,000 facilities throughout the U.S., Canada and overseas to help them solve their infection control requirements in a timely and cost-effective manner.

How do we determine which HEPA-CARE Air Purification System is best for our facility?

Our experienced sales consultants can help you decide which model or models to select, and what other accessory products are required or recommended. Abatement HEPA-Care Portable units, which can be relocated from room-to-room as needed, provide maximum flexibility, and are therefore ideal for shorter term surge-capacity requirements. As a general rule of thumb, our HC800C Ceiling-Mounted Model is ideal for longer term applications because it is completely out of the way of staff, and takes up no floor space. It can also be used to meet CDC requirements for point-of-use HEPA filtration of supply air to positive pressure isolation rooms (PE). Both types of units are designed for point-of-use HEPA filtration of exhaust air from negative pressure AIIR rooms.


Why can’t we just buy commercial portable air cleaners to meet our requirements?

Unlike HEPA-CARE systems, general-purpose recirculating air cleaners are simply not designed to meet the critical infection control requirements in accordance with CDC, UL, CSA, OSHA and AIA. Features include true, metal-frame HEPA filters that are 100% tested to ensure that they provide minimum filtration efficiency of 99.99% @ 0.3 microns, “zero bypass” construction, and the ability to operate in negative pressure, positive pressure and recirculation modes. HEPA-CARE Air Purification Systems are Class II medical devices and are safety certified by a Nationally Recognized Testing Laboratory.


Aren’t all HEPA filters pretty much the same?

Absolutely not. In many units, HEPA media filters are constructed with inexpensive particleboard frames that can warp, crack, off-gas and support microbial growth. In many instances, completed filters are not tested in accordance with Institute of Environmental Sciences and Technology IEST-RP-CC001.3 and MIL-STD 282. Damage to the media pack or leakage between the media pack and the filter frame that might compromise overall efficiency can therefore go undetected. The true Type C (99.99% efficiency @ 0.3 microns) gel seal HEPA-CARE filters are constructed with extruded anodized aluminum or galvanized steel frames, have a UL900 Class I flammability rating and meet IEST and MIL standards, including 100% testing. The unique silicone gel seal provides a more secure, bypass-free seal than other designs. Read the facts about true HEPA filtration.


How often should I change the HEPA-CARE filters?

This will vary depending on the size and concentration of contaminants, temperature and humidity conditions, and duration of use, but “change pre-filter” and “change HEPA” LEDs on the electronic control panel of our HEPA-CARE systems eliminates any guesswork. With continuous use, average primary filter life is one to two months. Timely filter changes are essential. When filters become loaded with particulate matter, the static pressure differential across the filters increases and the airflow output of the unit decreases. Regardless of the amount of use, the HEPA filter should be replaced every two years to ensure ongoing performance.


Are tools required for filter changes?

A ½” hex wrench is needed to access the filter compartment and prevent unauthorized access. Once this is done, filters are extremely easy to change and no tools are required.


Does changing filters in the Abatement HEPA-CARE ceiling mounted unit require removing ceiling tiles?

No. All HC800C filters are room-side accessible via a hinged, swing-down access door, so tiles do not need to be disturbed. The same holds true for the UV lamps in the UV400C-PT and UV400C UV modules.


How long should I run the HEPA-CARE unit between patients?

The CDC recommends 99.9% removal efficiency in the patient room. With 12 ACH, the waiting time should be approximately 30 to 40 minutes, but a one-hour minimum is a good policy adopted by numerous health care facilities.


How can Abatement Technologies products help us meet the most recent CDC Infection Control Guidelines?

Click to learn how Abatement Technologies solutions can help your facility meet CDC Guidelines for Environmental Infection Control in Health-Care Facilities.


Do the HEPA-CARE systems come fully equipped for negative pressure operation?

Complete, pre-packaged isolation room kits including the HEPA-CARE unit, a pressure monitor and other accessories are available


Should we exhaust the filtered air from an isolation room outdoors?

Yes, if possible. It is always preferable to exhaust HEPA filtered air to the outdoors as an added safeguard, though indoor exhaust is permissible under CDC Guidelines for AIIR rooms, which state: “Direct exhaust air to the outside, away from air-intake and populated areas. If this is not practical, air from the room can be recirculated after passing through a HEPA filter.” However, it is also important to check your state regulations, because many states do not permit recirculation. As a result, very few infectious patient isolation installations recirculate, except in emergency circumstances.


What if we have an emergency requirement where we can’t exhaust outdoors?

Abatement Technologies offers several potential solutions. One is to place a portable HEPA-CARE model in the room and duct the HEPA-filtered air above the drop ceiling via one of our ceiling exhaust plates. We would recommend either using the HC800F with the HC600FUV model. Another is to duct the filtered exhaust air into a corridor. A third is to install an Abatement IQ200 Bed Isolation Tent around the patient bed, use an ISOQUAD® IQ200 module. The filtered air is simply exhausted back into the room. We recommend selecting one of these solutions in advance and purchasing the equipment so it is on site and ready to go in advance of such an emergency.


Our facility has combination negative/positive isolation rooms. Do they still meet CDC Guidelines?

Not any longer. The 2003 CDC Guidelines describe these rooms as “unreliable”, especially in the negative pressure mode, and specifically recommend against their use in new construction or renovations. The Guidelines also discourage the use of these rooms in existing facilities.


How many air changes per hour (ACH) do we need, and how do we determine how many HEPA-CARE units we need to provide the required ACH?

CDC requires at least 12 ACH in any renovated or new isolation rooms (PE or AIIR), a minimum of 6 ACH in existing isolation rooms and at least 15 ACH in operating rooms (including 3+cfm of fresh air). Most facilities target at least 12 ACH even in existing rooms. One or more HEPA-CARE systems may be needed, depending on the size of the room in cubic feet (length x width x height to the drop ceiling). As with any air filtration device (AFD), factors such as filter loading, attached collars or ducting and reduced voltage to the motors will decrease actual delivered airflow. Click for the Air Change Calculator to determine the number of HEPA-CARE units needed to produce ACH.


How can we factor in and compensate for these conditions?

Too much airflow is always better than not enough. Add as much safety margin as is practical within your budget, especially where long duct runs are required. A good rule of thumb is to design for 25% to 50% or more ACH than required to compensate for potential airflow losses–the more the better. In other words, if 12 air changes are the objective, design for at least 15 to 18 ACH. For information on the number of Abatement HEPA-CARE units required for various room sizes, please click for the Air Change Calculator.


How is the Abatement HEPA-CARE system disinfected after use?

We recommend that you wipe down the system with a water-based germicidal. Although changing the pre-filters between patients is not required, it is recommended for portable units that could be moved to another room. If filters are not changed in portable units, it is advisable to seal off the openings around the inlet door before the unit is moved. Many facilities replace the pre-filters between patients in all units, including ceiling mounted models.


How often do we need to have the HEPA-CARE units tested?

The 1994 CDC TB Guidelines recommend quantitative leakage and filter performance testing after installation and every six months thereafter, or whenever the HEPA is replaced. This is a good guideline. Most facilities use the same company that tests and certifies biological safety cabinets.


Where should the system be located in the patient's room?

Abatement Portable In-Room Systems should be positioned at a maximum distance from the door to the corridor so as to create a directional airflow away from the corridor and the healthcare worker. Abatement Ceiling-Mounted Systems are generally installed over the patient's bed and should be located as far as possible away from the room supply air diffuser to minimize "short-circuiting" of air.


What is "short-circuiting"?

Short-circuiting occurs when the air supplied to the room by the facility HVAC system passes directly into the HEPA Filtration System without first being circulated through the room. This can reduce the effectiveness of the system for reducing airborne concentrations of TB droplet nuclei within the room.


Is pressure monitoring required?

Yes. CDC requires daily room differential-pressure monitoring, but this may be insufficient to catch pressurization problems on a timely basis. Our state-of-the-art continuous electronic monitors eliminate the need for daily, time-consuming smoke tube testing, provide continuous real-time monitoring, and a 24/7 record of these conditions. Learn more about Abatement Technologies HEPA-CARE Room Air Pressure Monitors for Negative or Positive Pressure Patient Isolation Rooms.


Are anterooms required?

In general, the CDC Guidelines include design parameters for isolation rooms with and without anterooms. Anterooms are recommended for certain special situations, such as isolating a TB patient after surgery, or isolating smallpox or viral hemorrhagic fever (VHF) patients. The 2003 CDC Guidelines illustrate two options for these situations, one with a neutral anteroom and one with an anteroom under negative pressure related to both the patient room and the corridor. If a room with an anteroom is not available, CDC recommends using portable HEPA units in the room to provide additional ACH equivalents. Learn more about Portable Anteroom Modules from Abatement Technologies.


Does my isolation room need to be tightly sealed?

No. Isolation rooms depend on air that infiltrates into the room (for negative pressure) or out of the room (positive pressure) through the gap under the door and through other small openings. It is not necessary to replace drop ceilings with solid ceilings to maintain sufficient differential pressure and ACH.


In a negative pressure infectious patient isolation room, it is essential to seal off any air returns to ensure that the only air that passes through the HEPA-CARE unit or units is exhausted from the room. Maintaining suitable negative pressure levels may also require dampering down supply air to ensure that more air is exhausted from the room than supplied to it. If this is not possible and supply air volume is substantial, additional or larger HEPA-CARE units may be required to maintain the proper pressure differential. In positive pressure rooms, the reverse applies. Supply air diffusers must be sealed off and return air volume must be controlled relative to the exhaust airflow of the HEPA-CARE unit.

What is the estimated shipping time of your HEPA-CARE systems?

We do our best to keep enough inventory on-hand for shipment within 24 hours. Very large orders that must ship complete may require additional time. Approximate transit time within the continental United States is two to seven days. You will be notified if there are any anticipated delays at the time of order placement.


What is the warranty of Abatement HEPA-CARE Air Purification Systems?

Abatement stands behind its products. All systems are covered by a comprehensive limited warranty to the original user against defects in materials and workmanship for a period of two years after date of purchase. Over the past 20+ years HEPA-CARE systems have proven to be extremely reliable, and both warranty and non-warranty repair requirements have been very minimal.


Do the CDC SARS Guidelines differ significantly from the CDC TB recommendations?

No. Similar precautions are recommended, including isolating suspected or known infected patients in negative pressure AIIR rooms. The same principles hold true for avian influenza, swine flu or any other infectious organism with the potential for airborne transmission.


Is the effectiveness of HVAC-mounted germicidal UV lamps against airborne bacteria and viruses been recognized by health professionals?

Centers for Disease Control and Prevention Infection Control Guidelines recognize the effectiveness of ultraviolet germicidal irradiation (UVGI) lamps for providing supplemental protection and effective ACH when mounted in upper room air or connected into the facility HVAC system. Abatement Technologies offers four UVGI options, including: the UV800F, which mounts onto our HC600FUV HEPA-CARE model; and, our ceiling-mounted UV400C-PT and UV400C UVGI modules.


How do the requirements for patient isolation during bioterrorism response differ from H1N1 or SARS?

In most instances they are virtually identical: identify infectious or potentially infectious patients, and isolate them in negative pressure infectious patient isolation rooms. The same principles apply. That’s what makes HEPA-CARE systems so versatile.


What do you mean by “aircraft type construction”?

Fasteners such as sheet metal screws and hollow pop rivets are cheaper and easier to use, but they provide potential leakage points for sub-micron particles and bio-pollutants. HEPA-CARE devices are constructed using aircraft grade aluminum cabinets, solid leak-proof aircraft type aluminum rivets and sealed critical seams. In addition, in most air filtration devices, the section of the cabinet downstream from the HEPA filter remains under negative pressure (a vacuum). This means that “dirty” room air can be pulled into the cabinet and exhausted without ever passing through the HEPA. HEPA-CARE units maintain positive pressure downstream from the HEPA to ensure that dirty room air can’t leak into that section of the cabinet.



FAQs About Killing Microorganisms on a HEPA Filter with UV-C Lamps

How is UV-C exposure quantified?

UV dosage, which is typically expressed in microwatts per square centimeter, is based on four factors:

  • Direct exposure to the UV-C irradiation source
  • The intensity of the UV-C source
  • The distance away from that source
  • The duration of exposure

Because organisms in rapidly moving airstreams are exposed to the UV-C source for only fractions of a second, effective disinfection requires very high-intensity UV-C output and very close proximity to the lamps. This is especially true for more complex organisms such as fungi, which typically require five to 20 times more UV-C energy to destroy than bacteria.


Why is proximity to the lamp so important?

Studies have shown that UV-C dosage decreases by approximately the square of the distance from the lamp. In other words, compared to dosage one inch away from the lamp, dosage is four times lower at 2 inches away, sixty-four times lower at 8 inches away and 144 times lower at 12 inches away. In some air filtration systems, organisms that pass the lamps or are trapped on the media can be as far as 12 to 48 inches away from the lamp.


Can UV lamps shining on the inlet face of a HEPA filter kill all of the organisms trapped on the media?

This would be highly doubtful because the lamp can't kill what it can't "see". HEPA filters are designed with very closely spaced pleats, with typical pack depths of anywhere from three to four inches up to 12 inches. It's highly unlikely that a lamp or lamps shining on the inlet face of a HEPA filter would expose microorganisms trapped on the inlet surfaces of the pleated media pack much beyond the first half-inch to one inch of depth, especially for pleats that are farthest away from the lamp(s). As a result, effectiveness would likely be limited to only a small percentage of the media area.


Why should contaminated air be filtered before it reaches the lamp(s)?

Filtration systems that do not pre-filter air before it gets to the lamp(s) and the HEPA filter can expose the lamp(s) to larger dust and dirt particles. This can result in the formation of a dirt film deposit on the quartz glass and significantly reduced UV-C intensity. In addition, agglomerated dirt particles that form on the HEPA filter media can reduce airflow and filter capacity, shorten filter life and further block UV-C exposure to organisms that may be trapped beneath them. With the design of an Abatement HEPA-CARE Air Purification System, air is pre-filtered and HEPA-filtered before it is exhausted into the UV-C module, thus maximizing UV intensity to kill microorganisms.


Couldn’t a pre-filter be used to reduce lamp-contamination problems for the internal lamp systems?

Yes, but then the pre-filter media must be protected from exposure to the lamp(s). High-intensity UV-C radiation can rapidly break down and pulverize most pre-filter media, especially synthetics, cotton and blends. Exposed components such as electrical wiring and rubber gaskets can also be degraded if not protected properly. HEPA media is much more UV-resistant, but lamps must be still kept far enough away from the media to ensure that the UV-C energy won’t destroy filter integrity by breaking down filter binders and adhesives, and won’t cause VOC off-gassing.


How are patients and workers properly protected from accidental UV exposure?

Because direct UV-C lamp exposure can seriously damage the eyes or the skin, extra precautions are needed to ensure that patients, healthcare workers or maintenance personnel are not exposed to the UV-C lamps during normal use or when replacing filters. This is a much more difficult task when the lamps are located on the inlet side of the HEPA filter.

With our design, the separate UV-C modules keep the lamps isolated from the filter compartment and are accessed only about once a year for lamp replacement. Built-in safeguards, such as electrical interlock switches, instantly deactivate the lamps when the access door is opened. It is also very important to ensure that the overall unit has been safety tested and certified by a Nationally Recognized Testing Laboratory (NRTL) such as UL, ETL or CSA. Abatement's germicidal UV-C modules meet this requirement.


FAQs About Product Safety Certification

You really emphasize the fact that Abatement products are tested and certified by ETL, a Nationally recognized testing Laboratory (NRTL). What are the requirements?

In the USA, OSHA safety standards for general industry and construction and the National Electrical Code require testing and listing (certification) of electrical products to applicable standards. It is important to note that this testing must be performed on an electrical device even if the individual electrical components used in that device are all listed or approved. Testing must be done by an OSHA-recognized NRTL, such as UL (Underwriters Laboratories), ETL (Environmental Testing Laboratories) or CSA (Canadian Standards Association). In Canada, The Standards Council of Canada has adopted standards for the Canadian Electrical Code developed on its behalf by the Canadian Standards Association (CSA). Third party testing from a laboratory or other organization, not NRTL-certified is not acceptable, even if such testing is done to applicable standards.


Why is NRTL certification so important?

Unless a unit is properly tested, users have no way of knowing whether it is properly and safely designed to meet the requirements of the applicable electrical codes. It is wise to require written vendor verification that the products you purchase are NRTL certified. Learn more about NRTL safety certification in healthcare facilities.


Aren't all air filtration products properly certified?

No. Unfortunately, many of the air filtration systems sold to and used by contractors, healthcare facilities and others are not certified, especially negative air machines.



HEPA-CARE Systems are user-friendly and easy-to-control with a password protected, color LCD touch pad.

HEPA-CARE Systems are user-friendly and easy-to-control with a password protected, color LCD touch pad.
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