Is your hospital protecting patients, visitors, and employees from airborne contaminants that may compromise their health or their families’ health? The United States Department of Health & Human Services publishes requirements relating minimum levels of air filtration efficiency. The requirements also define filtration by area, and note additional items such as required air changes per hour, recommended temperatures, recommended relative humidity, and the relative room pressure with regard to the rest of the facility.

Medical facility HVAC systems are unusual in that two filter beds are recommended, one upstream of the coil, and a final filter bank downstream of the coil. Standard HVAC systems place both stages upstream of the coil.

Filtration requirements for medical facilities are not a new concept. The original requirements were published in 1947 under the Hill-Burton Act. In the 50 years plus since then, the requirements have been modified to current filtration and microbial contamination control technologies.

An example of a recent change relates to our renewed concerns over restricting the airborne bacteria, mycobacterium tuberculosis. Infectious patient isolation room requirements were changed from 6 to 12 air changes per hour, with a defined negative pressure of 0.001 or 100 feet per minute inward velocity.

The American Society of Heating, Refrigeration, and Air Conditioning Engineers mirrors most of these requirements. In orthopedic, bone marrow transplant, and organ transplant operating suites an additional stage of HEPA filtration is recommended at the air outlets.

Efficiencies as listed on the enclosed chart refer to dust spot efficiency as rated under ASHRAE Standard 52.1-1992. As ASHRAE Standard 52.2, testing filters based upon particle size versus efficiency, becomes the common methodology; the common filters of application will have minimum efficiency rating values (MERV’s) of MERV 7 before the coil and MERV 14 as the final or secondary filter.

Additionally, the requirements define minimum air intake locations and air outlet requirements. Outdoor intakes should be located as far as possible above the ground with a minimum level of 6 feet. Roof level intakes should be located at least 3 feet above the roof. Outdoor intakes must also be at least 25 feet from any exhausts or combustion equipment (venting). Room air supplies should be located at or near ceiling height.

DP Filters, Inc. offers visual presentations detailing medical facility requirements. Contact your sales representative for additional information.