New York City Department of Health and Mental Hygiene "Guidelines on Assessment and Remediation of Fungi in Indoor Environments" (November 2008), 6.

"Non-porous materials (e.g. metals, glass, and hard plastics) can almost always be cleaned. Semi- porous and porous structural materials, such as wood and concrete can be cleaned if they are structurally sound. Porous materials, such as ceiling tiles and insulation, and wallboards (with more than a small area of mold growth) should be removed and discarded. Wallboard should be cleaned or removed at least six inches beyond visually assessed mold growth (including hidden areas, see Visual Inspection) or wet or water-damaged areas.²⁴"