The air supply from an airliner ventilation system is a mixture of outside air and recirculated air that passes through a high efficiency particulate air (HEPA) filter. The effectiveness of two commercial-available airliner cabin air filters were investigated in laboratory-based measurements due to the practical restrictions on airliner cabin filter testing during usage. The filtration efficiency and pressure drop were assessed at a particle size range of 20-500 nm under various airflow rates throughout the filter usage period. The Most Penetrating Particle Sizes (MPPS) were observed at ~150 and ~55 nm, where the filtration efficiency was 86% and 99% at the rated airflow rates (1600 m 3 /h and 1970 m 3 /h), respectively. The filtration efficiency decreased in response to the increased airflow rate from 1000 m 3 /h to 2200 m 3 /h, with the greatest reduction (~10%) occurring at MPPS. An increase of 250 Pa in the pressure drop across the filter was observed as the airflow rate increased from 1000 m 3 /h to 2200 m 3 /h. Increased filter usage led to increases in both filtration efficiency and the pressure drop. The actual filter usage was estimated using dust loading in the laboratory. Filtration efficiency increased ~10% and the pressure drop increased ~800% when 220 g/m 2 dust was loaded on the filer, corresponding to ~6000 hours filter usage at an in-cabin PM 10 concentration of 100 μg/m 3 . Explicit relationships among filtration efficiency, pressure drop and filter usage under various in-cabin particle concentrations are presented as a reference to facilitate the use of more appropriate airliner cabin air filter exchange periods.

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