| 摘要 |
A method for determining whether an item has been exposed to an environmental condition during a monitoring period. The method includes placing a sensor at least in proximity to the item at the beginning of the monitoring period so that the sensor will be exposed to a level of an environmental condition that can be correlated to an exposure level of the item to the environmental condition; reading the sensor; and determining from reading the sensor whether the item has been exposed to the environmental condition. The sensor includes a detecting material comprising a photochromic or photothermochromic material, the detecting material selected so that upon exposure to the environmental condition the detecting material exhibits a detectable color change.
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