This policy was created as a direct response to the Chernobyl Disaster. An interesing historical note is that the USSR and the Ukranian SSR were among the 69 states that signed the convention at the 1986 meeting, and both quickly ratified it afterward.
This policy applies internationally, to 119 states who were subject to it after the entry to force date. 69 states signed the convention at the IAEA special meeting in 1986.
This policy was innitially well recieved and was quickly ratified by a number of countries with major nuclear capabilities. However after the Fukushima Disaster, this policy and other international policies were percieved by the public to be slow and inefficient in spreading vital information.
The convention was drafted and signed at a special meeting of the IAEA that took place 5 months after the Chernobyl Disaster. No one author or author country could be determined based on the document.
This policy would help provide first responders and technical professionals with specific information on a nuclear emergency from a forign source which they could be responding to. This information could allow them to more effectively mitigate the effects of such a disaster.
The policy is the IAEA: Convention on Early Notification of a Nuclear Accident. Written in 1986, it aimed to create an international system for reporting a nuclear accident, transferring vital information from the source to those who would need it to facilitate effective emergency response.
This policy doesn't specifically address the needs of vulnerable popluations.
By establishing for effective communication of information regarding a nuclear accident to other states which could be effected by it, and creating policies for the transfer of information, the convention addresses public health by giving goverments access to the information needed to respond to a nuclear disaster from abroad.