Which detection method provides warning in sufficient time to implement protective measures before exposure to an agent?

The method that provides a warning in sufficient time to implement protective measures before exposure to an agent is detection to warn. This approach is designed to identify the presence of potentially harmful agents before individuals are affected, allowing for proactive measures to be taken. This early warning can be crucial in scenarios where immediate response is required to protect personnel and mitigate risks associated with exposure.

In contrast, environmental sampling involves collecting and analyzing samples from the environment to detect contaminants, which may not always provide real-time alerts. Medical screening refers to assessing individuals for symptoms of exposure or illness, which typically occurs after an exposure event. Incident analysis involves evaluating past incidents to understand what occurred, which does not provide proactive warning. Thus, detection to warn stands out as the method specifically aimed at providing timely alerts for effective preventive action.