Earliest case: reported in November 2022 at a school in Northern Qom. 

Symptoms: nausea, vomiting, fatigue, headache, and numbness after smelling various odors. 

Very few cases were reported among boys. No official data has been published by the Iran government.

Scientists worldwide are suspecting: poisoning by chemicals like Chloramine used previously as a war weapon or anxiety response to fears of threat. 

The psychogenic hypothesis is not supported by many.  

A thorough investigation is expected to be carried out by the Organisation for the Prohibition of Chemical Weapons (OPCW), a part of the United Nations Chemical Weapons Convention.