A) If the source = fan/duct (point source)

1. Are emissions stable?
o Yes → n = 3 consecutive samples per source.
o No → align sampling with fluctuations: over 3 periods (for fluctuations measured in minutes) or take grab samples over a cycle (for fluctuations measured in hours).
2. Is lower uncertainty required?
o Yes → increase to 6–10 according to the accuracy requirements in Annex F.
3. Do not omit the flow rate (V̇) and aggregation across fans.

B) If the source = active area source (e.g. a biofilter)

1. Check whether v > 0.008 m/s (active).
2. Divide the area into sample cells according to the m² rules.
3. Select the method:
o full coverage (preferred)
o partial coverage: ≥25% (homogeneously)
o hood: cover ≥10% of the area of the cells, taking 1 sample per cell.