Since passive filters are the most widely used technology, passive filter tests tend to dominate the test standards. MERV (minimum efficiency reporting value) is the most commonly used measurement for filters. MERV is based on a single pass and is used for measuring passive mechanical filters. “This is the biggest challenge for manufacturers of polarized-media air cleaners,” Wiser explained, “there is no widely-accepted test protocol today that demonstrates the effectiveness of polarized-media.” Wiser continued, “Single-pass measurements don’t account for loading which is the trade-off for efficiency. For mechanical filters, loading is detrimental because it increases static pressure. And although static pressure is not an issue for electronic precipitating air cleaners, they lose efficiency as plates and wires get dirty. So ratings like MERV do not provide a universal indication of performance under real-world conditions.”

Filter Pressure Drop vs Dust Load
SAE Fine Dust