What Does Ultra-Low Penetration Air Filter (ULPA) Mean?
Ultra-low penetration air (ULPA) filters can filter out all but 0.001% of airborne particles, pollen, dust, mould or bacteria. ULPA filters are able to filter out all particles up to 120 nanometres in size. In contrast, HEPA filters will only filter out particles up to 300nm and larger.
Safeopedia Explains Ultra-Low Penetration Air Filter (ULPA)
These ultra-efficient filters are generally used in nanoparticle containment rooms where processes involving the use of nanoparticles are conducted. Nano-particles may not be handled in open air situations, thus, nanoparticle containment rooms are used and those who conduct work in them wear appropriate PPE. An example of the kind of activity in which ULPA filters would be used is in medical research laboratories. Specific practices are applied to the ventilation and opening of nanoparticle containment rooms.