OPERATION LAC

1. Public Record

Operation LAC, Large Area Coverage. United States Army Chemical Corps, 1950s into the 1960s. Aircraft and blowers release zinc cadmium sulfide, a fluorescent tracer, over American cities and countryside to see how a cloud would travel if someone else had released something worse. St. Louis is the name that later hurts: poor neighbourhoods, schools, a housing project, people who were not told. Minneapolis, Winnipeg in a joint test, other routes. The tracer is chosen because it can be caught on filters and lit up. Cadmium is the part of the sentence the later lawsuits learn to say.

Official purpose is defensive study of air-mass movement. Official practice is to treat cities as grids. FOIA and reporting in later decades pull the maps. The Army calls it a simulant. Residents call it what was put over their streets without a meeting. Both sentences are in the record. Neither un-sprays the years.

A cloud chosen because it glowed on a filter. Streets that did not consent.

Zinc cadmium sulfide, a fluorescent tracer.

2. Date of Incident

Principal spraying 1950s-1960s. Later disclosure and litigation across decades after.

3. Location

Multiple U.S. cities including St. Louis and Minneapolis, plus joint work toward Winnipeg. Approximate 38°38 N 090°12 W for the St. Louis weight.

4. Official Narrative

A meteorological and defence simulant program. Official narrative later concedes the tests and disputes the harm. It does not concede consent.

5. Witness Layer

Chemical Corps crews. City residents who learned the name years after. FOIA reporters. Later plaintiffs.

People who were not told.

The Army calls it a simulant. Residents call it what was put over their streets.

6. Recovery Logistics

Filter papers, maps, later files. No un-spraying. Lawsuits instead of a recall.

7. Assessment

Keep Large Area Coverage as the official title so the acronym is not a mystery. Keep St. Louis in the first page because that is where the later harm argument concentrates. Do not write a cartoon of a death cloud from a tracer. Do not write consent that was not asked. A simulant is still a thing you put in someone's air. The filter glow is why they chose it. The un-asked streets are why the file will not close.

8. Materials & Remains

Test maps. Filter logs. FOIA. Litigation paper.

9. Key Personnel

Army Chemical Corps : The aircraft and the blowers.

Unnotified residents : The grid.

10. Aftermath

The maps come out late. Cadmium becomes a courtroom word. The tests do not get run that way again under this name. The years over those streets do not come back.

11. Current Archive Status

Status: 1950s-60s spray. ZnCdS tracer. Cities unnotified.

Confidence: High that LAC released zinc cadmium sulfide over U.S. cities as a tracer. High that residents were not asked. Low that any later page is a full medical ledger.

Filing note

A Chemical Corps cloud, a powder chosen because a filter could see it, a housing project that was a cell on a map, a city that learned the name when the children were already grown.

People who were not told. The only consent line the operation ever wrote.