With nearly 100 years of experience, AAF offers the best clean-air solutions. Its products include simple roughing filters, air-pollution control, gas-containment removal and the highest efficiency filters used in the most stringently clean environments. Based in Louisville, Kentucky, AAF operates in 22 countries around the world and employs more than 3,000 employees.


A long-time AAF (AmericanAirFilter) customer had been using AAF products at two of its three hospital campuses for several years. The third campus came on board with AFF in 2009. Final filters used in the hospitals consisted of DriPak bags, VariCel 1 and VariCel M-Pak filters, as well as limited HEPA filters employed in a new surgical suite.

Current filtration situation

Expressing the need to improve indoor air quality (IAQ) in critical areas, the hospital relied on AAF’s years of quality service to demonstrate the advantages of upgrading its final filters. With the understanding that hospital-related infections can cause significant economic consequences to any healthcare facility, AAF offered practical solutions for the hospital.

Technical situation

The hospital system had a variety of air-handing units (AHUs) that had ranged from two to 30 years of service. An AAF sales representative performed an air-filtration system survey, which revealed the need for improvement, particularly in the older AHUs.

The AAF solution

To help the hospital system make the best decision for its needs, AAF presented three solutions to consider.

A good option was to continue using MERV 14 VariCel M-Pak filters and upgrade where applicable; upgrade filter racks where needed; and inspect/replace gasketing and latches to ensure bypass is kept to a minimum. This solution came at the lowest cost with slightly better IAQ levels than before.

A better solution was to upgrade all final filters and filter racks to MERV 15 VariCel VXL filters. When compared with the VariCel M-Pak filters, this option demonstrated energy-cost savings and improved efficiency ratings of all final filters. Additionally, this option provided a longer filter lifecycle and improved airflow.

The best solution was to upgrade the final filters to AAF’s MEGAcel I HEPA filter with ePTFE technology. Traditional HEPA filters provide a much higher airflow resistance and would not typically be used without a costly upgrade to the AHUs. The MEGAcel I filter, however, provided the hospital with an option that was untraditional – HEPA filtration with the lowest possible resistance. This option gave the hospital optimal IAQ levels and energy savings as an added benefit.

Upgrade benefits

AAF worked with the hospital to provide options that would not just satisfy its IAQ needs, but also its budgetary requirements. Ultimately, the hospital decided to upgrade all three campuses to AAF’s MEGAcel I HEPA filters for the critical areas of the hospitals (ER, surgery and ECU). MEGAcel I HEPA filters meet the demanding airflow and efficiency requirements of critical applications in which airborne contaminants must be carefully controlled.

Once the MEGAcel I filters were installed, a particle count test was conducted in the AHU system. The test measured the amount of particulates in the system upstream and downstream from the newly installed MEGAcel I filters, compared with the MERV 14 filter-particle count results. The results verified the dramatic improvement to the hospital’s air quality (see graph above).

The hospital system also decided to upgrade patient care and non-critical areas to AAF’s VariCel VXL filters. PerfectPleat HC M8 filters were used as pre-filters. The hospital system now has substantial validation that it is providing the best air quality for its patients and staff.