MERV-17 HEPA (99.97% DOP efficient at 0.3 microns)
Dirty air passes through the prefilter. The prefilter removes large particulate. The primary filter then captures the remaining particulate. As the contaminant load on the filters increases, the filters become more efficient in capturing the smaller particles. At the same time, however, the dirty filter allows less air to pass through resulting in less particle collection and a decrease in the overall effectiveness of the air cleaner. The XJ-2 air cleaner is equipped with a pressure gauge which indicates the restriction to airflow caused by the filters loading with particulate. When the air filter gauge reaches the red arrow or a noticeable reduction in airflow occurs, it is time to clean or replace the prefilter and possibly the primary filter. The CDC guidelines specify that the HEPA filter shall be replaced every six months.