Final answer:
The query about the first Air Police shield is historical but cannot be answered with the provided references. The information on segregated military units and Vietnam War herbicides does not pertain to the Air Police shield.
Step-by-step explanation:
The original question concerns the historical origin of the first Air Police shield and not specifically the segregated units during World War II or the use of aerial herbicides in Vietnam; hence, information from those conflicts would not accurately address the query provided. The question, as it relates to the issuance of the first Air Police shield, might pertain to the history of military police in the United States Air Force (USAF).
However, without precise historical accounts or records mentioned regarding this particular event, it's impossible to provide a definitive answer. Furthermore, the given references to the 82nd Airborne's segregated units and Operation Ranch Hand's herbicide missions in Vietnam do not contain information related to the Air Police shield's issuance.