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HEPA Filter Applications Guide
HEPA Filters For Surgical / Operating Room Air Purification

by Richard Carrow (Danforth Air Filtration & Air Purification, Buffalo, NY)

HEPA filters used in surgical operating room, and other critical medical air filtration applications, must provide the highest quality of air cleanliness, helping safeguard the life and health of both patients and medical staff. All Healthcare HEPA filtration systems should only be designed and installed by experienced engineers with specialized expertise in HEPA filters and HEPA air purification systems.

Danforth Air Filtration & Air Purification and Danforth Indoor Air Quality Division work together to maintain Your HVAC / Air Filters / Air Cleaners / Air Purifiers, and coordinate required periodic testing and preventive maintenance on all types of air filtration & air purification systems in New York State

High-Efficiency Particulate Air Filters (HEPA Filters), are a form of extended surface media air filters previously known as High Efficiency Particulate Arrestors. A ’True’ HEPA filter must be at least 99.997% efficient - allowing no more than 3 particles in 10,000 to penetrate the filtration media.

Healthcare HEPA Filter Systems - Applications

Specialized medical procedures impose various demands on healthcare facility HVAC air filtration and air purification systems, which must continuously operate at the highest efficiency. This usually includes operating theaters, outpatient surgery suites, labor and delivery departments, bone marrow transplant, isolation rooms, critical care, intensive care, and several other areas.

The High Efficiency Particulate Air (HEPA) filter provides the best protection from infection and contamination by airborne microorganisms, especially when engineered so that the filter is mounted at the terminal of the duct, commonly referred to as ceiling mounted HEPA filters or modules.

HEPA filters have a long history of providing protection against airborne diseases, yet today, there is no ordinance, federal regulation, or even a mandate to have them installed in hospital operating rooms. The American Society of Heating, Refrigerating and Air Conditioning Engineers (ASHRAE), the American Institute of Architects, (AIA) and the Joint Commission for the Accreditation of Healthcare Organizations (JCAHO) all recommend HEPA filtration and JCAHO serves as an accreditation organization to monitor hospitals and medical care facilities.

Healthcare HEPA Filter Systems - Requirements

JCAHO requires hospitals to design, install, and maintain ventilation equipment to appropriate pressure relationships, (positive or negative) air exchange rates, (air changes per hour) and filtration efficiencies for ventilation systems areas specially designed to control airborne contaminants (such as biological agents, gases, fumes, and dust particles).

These specially designed areas include special procedure rooms, delivery rooms with patients diagnosed or suspected of having airborne communicable diseases, patients in protective environment rooms (those with immunodeficiency conditions or bone marrow transplant patients). Also included are laboratories, pharmacies, and sterile supply rooms. Most healthcare facilities that do utilize HEPA filtration in critical care areas apply this technology because they understand the value in terms of reducing the number of nosocomial infections (those arising while a patient is in a hospital or as a result of being in a hospital).

HEPA Filter Systems Suppress Infectious Agents

The CDC estimates that over 90,000 people die each year from nosocomial illness. They also state that over 50% of these cases are preventable. One way to help prevent this is by utilizing high quality HEPA filters in the air distribution system. In fact, the ASHRAE Handbook (2003, Health Care Facilities 7.3, Table 1) recommends MERV 17 (or 99.97%) HEPA filters at the outlet of Orthopedic, Bone Marrow Transplant, and Organ Transplant Operating Rooms.

Transmission of diseases by the airborne route is usually done by droplet nuclei, small droplets of moisture, or dust particles in the size range of 1 to 5 micrometers. These small particles can stay suspended in the air for long periods of time. Small microorganisms and viruses usually "ride" on these particles that can affect open wounds or are breathed into the deep lung section where they can cause potential disease and infection.

Although the sources of these contaminants are many, people are the biggest carrier of contaminants, requiring extensive covering of operating room personnel with clean garments to prevent contamination.

Poorly maintained HVAC units are also responsible for unwanted contaminants entering a room via the HVAC distribution system. Therefore, the terminal HEPA filter is the popular choice to provide maximum filtration from any airborne contaminant that might enter the HVAC unit or ductwork downstream of in-line unit-mounted HEPA filters.

Ceiling Mounted HEPA Filter Systems

Ceiling mounted HEPA modules deliver clean, filtered air in a flow to the room that provides a sweeping effect pushing contaminants out via the return grilles - that are usually mounted on the lower wait. While there is no true laminar airflow, this top to bottom flow closely duplicates a "piston-effect".

With ceiling mounted HEPA units, the air is as close to laminar flow in operating rooms as is feasible, based on the various types of equipment and instruments that typically interrupt laminar airflow patterns.

Ceiling Mounted HEPA Filter Schematic

Surgical HEPA Filters Summary

Ceiling mounted HEPA filters in healthcare facility operating rooms must provide the highest quality of air cleanliness, helping safeguard the life and health of both the patients and the healthcare workers.

These critical Healthcare HEPA filtration systems should only be designed and installed by experienced engineers with specialized expertise in HEPA filters and HEPA filtration systems.

All HEPA filtered systems should be designed to incorporate scheduled periodic in-situ testing of filters, gaskets and housings, with appropriate challenge agents and testing equipment. This usually involves an upstream introduction of DOP (or some appropriate acceptable challenge agent) and downstream scanning of the face of the HEPA filter with a forward light-scattering photometer. This testing procedure allows the system to be integrity-tested and certified to assure that there are no leaks in the critical components of the HEPA filter ceiling module.

When replacing Your HEPA filter, it is critical that you obtain the correct HEPA Filter. Use the Danforth Replacement HEPA Filter Worksheet - Print And Complete The Form And Fax To 716.832.7758.

Air Filration & Air Purification Expertise

Danforth is a certified NAFA member with over 20yrs experience in HVAC air filtration and HEPA Air Purification systems. We conduct HVAC System Audits, and can help you find the optimum HEPA Air Purification System for Your facility.

Danforth HEPA testing and certification experts can advise you on your Healthcare HEPA filtration and air purification application, and make sound recommendations to optimize your system to maximize performance and minimize ongoing maintenance & cost.

Danforth’s NEBB certified Balancing Division can schedule HEPA Air Purification System Testing & Certification at Your facility in New York State.

$SAVE$ - Discount pricing on quality Air Filters, Air Cleaners & Air Purifiers at www.danforthfilters.com. Visit the Secure Online Store for standard air filter sizes. For custom-sized air filters, use the Custom Air Filter Configuration Tools to build and buy your own filter.

Danforth Air Filtration & Air Purification - Replacement Air Filters, HEGA Air Purifiers, & Associated Filters. NAFA Certified Specialist For Residential, Commercial, & Industrial HVAC And HEGA Air Purification

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On-Site Service
(In New York State)

Danforth also conducts HVAC system assessments and provides a detailed 3rd party report using our Aircuity™ HVAC monitoring and assessment equipment.
To Schedule A HEPA Filter On-Site Scan, Test, & Certification In Your Building
Contact Danforth’s National Environmental Balancing Bureau (NEBB) Certified Balancing Division
M-F, 8am to 4pm EST
Call: 716.829.1345



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Contact Danforth Air Filtration & Air Purification
Danforth Air Filtration & Air Purification, Buffalo, NY
Buffalo, New York, USA
Call: 1.866.581.4999