WallChek sample [WC]

Published: July 8th, 2009

Revised: March 24th, 2023

The WallChek sampler is a minimally invasive way to test wall cavities for the presence of fungal contamination. The device consists of an Air-O-Cell® sampling cassette outfitted with a 50 cm sampling tube 2.5 cm in diameter attached to the slit face of the impactor. A hole is drilled into the wall assembly to be checked, and the tube is inserted through the hole into the wall cavity. A sampling pump is used to draw air through the cassette at a rate of 15 L/min¹ for 30 sec to 1 min during which time the wall may be gently tapped to release any adherent spores from interior surfaces.

Field sampling method

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Laboratory code: WC

Service options

Results reporting

Results of WallChek® samples are reported semiquantitatively by fungal group observed, as 1+, 2+, 3+, etc., where the numeral preceding the plus sign indicates the order of magnitude of particles observed in an average 600× or 1000× microscopic field in the central portion of the trace. Background levels are typically very high in WallChek® samples. Nevertheless, they may provide useful information on the condition of the interior of a wall assembly without excessive disruption and minimal risk to investigators and occupants. Quantitative results cannot be provided for this sample type.