Active microbial air sampler aspirates a known volume of air that impacts at constant speed on the agar media surface collecting viable particles of different size in microns.
With Passive method (settle) the viable particles fall naturally onto the surface of an open Petri dish and their collection vary based on air flow, humidity, temperature and size of micro-organisms.
The active method reports quantitative results in the format of cfu / 1000 litres of air (=1 cubic meter); the settle method reports the results that fall on open agar surface in 4 hours.
The number of cfu collected by the active method is much larger that with settle method and the quantitative results can be applied to action and alert levels.
