Meltblow = high level filtration with little effect suction power and airflow.
Ideal humidity controlled Cleanroom use as allows pick-up moist air and dust.
Activated carbon = Neutralising moist smells and ordors. Arrests moist from air.
HEPA = High Efficiency Particulate Air: 99,97% retention on 0,3µ particles
ULPA = Ultra low Penetration Air: 99,999% retention on 0,12µ particles.