When must phosphine level monitoring be performed and recorded?
Monitoring for safety of workers and bystanders is mandatory and is performed to determine (i) when and where respiratory protection is required; (ii) whether phosphine gas is escaping and is accumulating at unsafe levels in any areas; and (iii) to take proper actions to prevent accidental exposure. Once fumigation has started and gas containment has been adequately characterized, spot checks must be made, especially if conditions change significantly or if an unexpected garlic odor is detected or a change in phosphine concentration outside the fumigation area is detected. Section 15 of the Applicator’s Manual addresses safety monitoring. The only exception to monitoring for safety would be a situation where it can be confirmed/concluded by the certified applicator that there is no possibility of exposure to phosphine at or above the allowable limits to workers or bystanders. Monitoring must be done if there is even the slightest possibility of exposure. Exposures to phosphine must not
