At each sampling location a volume of air is sampled that is large enough to detect at least 20 particles if the concentration of the largest considered size were at the class limit, calculated from Formula A.2 from that class limit. Every location is sampled for at least 2 litres with a sampling time of at least 1 minute per sample, and every single sample volume at every location is the same; where the volume would be very large the optional sequential sampling procedure of Annex D may be used to reduce volume and time.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.