Takenami et al. (1989), in their study "Air Conditioning and Particle Filtration Systems for Energy Saving," conclude that:
[T]he most effective means for reducing the energy required to deliver clean air is to employ high performance filters which are designed to minimize pressure loss.... The concept behind the sodium elimination unit is to remove impurities at the point furthest upstream from the cleanroom by installing high efficiency filters behind the prefilters located at the external air intake port. Based on the premise that sodium may permeate the filters due to deliquescence if the humidity of the external air exceeds 60 percent, the external air is heated immediately before the filter to regulate humidity to less than 60 percent in order to eliminate sodium.
