A similar thing happened after the Fukushima disaster. People are remarkably altruistic and cooperative in these scenarios. Often times when society is under stress social order doesn't breakdown but instead becomes more rigid.

>> People were carrying pieces of undeveloped film to determine cumulative level of radiation after trips there.

This is still a standard dosimetry measurement in the West (film has a very long integrating time so cumulative exposure over a week or two can be reliably tracked).