The particle count values per cubic metre are updated every minute, upon the arrival of new data from the last cubic foot measurement. The count per cubic metre is computed by accumulating the number of particles measured over the last 36 individual cubic foot samples, then scaling the accumulated count by 35.31/36, to compensate for the fact that there are 35.31 cubic feet in a cubic metre, not 36. This technique allows the earlier detection of out of compliance values, rather than waiting nearly 36 minutes for a cubic metre to be sampled. A full count over a cubic metre, however, can only be indicated after 36 or more minutes of continuous operation.

Take a look -> Example m3 Calculation