action level

noun

: the level of concentration of a harmful or toxic substance or contaminant (such as lead, asbestos, benzene, or radiation) that when exceeded is considered sufficient to warrant regulatory or remedial action

Two-thirds of the more than 6,000 homes it tested in 2003 had lead levels exceeding the Environmental Protection Agency's "action level"—the safety level at which federal law requires a water system to take prompt steps to reduce lead levels and notify the public.—

Erik D. Olson, Washington Post, 8 Feb. 2004

Future clam digs are dependent on marine toxin levels, but the first set of samples dug last Sunday showed all results were still below the action level.—

Mark Yuasa, Seattle Times, 25 Oct. 2009