At CBRN MOPP level 1, what action is taken?

At CBRN MOPP level 1, the appropriate action taken is to set yoke. This level indicates a heightened alert state where personnel need to be prepared for potential chemical, biological, radiological, or nuclear threats, but actual protective equipment is not yet required beyond basic readiness.

Setting yoke involves ensuring that the ship or unit is prepared for a crisis while not fully engaged in protective measures. This readiness ensures that personnel are able to transition smoothly to higher levels of preparedness if the situation worsens and allows for a swift response to any emerging CBRN threat.

The other actions listed involve different levels of readiness or specific actions that may not be applicable at MOPP level 1. Setting material condition zebra typically refers to a specific state for securing equipment and compartments not directly related to CBRN preparedness. Setting GQ, or general quarters, indicates a more severe alert where crew members prepare for immediate action, and issuing PPE (personal protective equipment) would occur at a higher MOPP level when there's a confirmed or imminent CBRN threat.