Case file · High strangeness
Mad Gasser of Mattoon
An Illinois town reported a prowler spraying a sickly-sweet gas causing paralysis and nausea.
1944 CE · 39.48, -88.37 · status: disputed
The account
Over two weeks residents of Mattoon reported a 'gasser' attacking homes; symptoms and sightings spread rapidly before ceasing.
The sceptical view
Widely cited as a textbook case of mass psychogenic illness amplified by newspapers.
The researched reading
A classic panic: perhaps one real incident, multiplied by newspapers and wartime fears into a wave of attacks that left no trace.
| Explanation | Weight | Why |
|---|---|---|
| Perception, memory or mind | 50% | In September 1944 reports surged after sensational front-page coverage and stopped when police and papers called it hysteria; symptoms (nausea, numbness, palpitations) are typical of anxiety and no physical evidence of a gas or attacker was found. Donald Johnson’s 1945 field study became a textbook case of mass psychogenic illness. |
| Undetermined | 17% | The share the reading had given to fabrication on doubt rather than evidence: the record does not settle it either way. |
| Something in the surroundings | 15% | Mattoon had chemical plants and a sweet odour could have been industrial pollution, which may have triggered the first real complaint. |
| A cultural story | 8% | Wartime fear of gas attacks and saboteurs gave the story its shape. |
| A hoax or fabrication | 5% | A real prankster or prowler may have caused the first incident (some researchers name a local chemistry student), and copycat or false reports followed; Johnson’s study has been criticised for assuming hysteria. |
| Genuinely anomalous | 3% | No evidence of anything beyond human and social causes. |
| A known natural phenomenon | 2% | No natural gas source was identified. |
Official position: Police concluded it was mass hysteria, possibly started by a real odour; no gasser was found.