Nearly 1,000 Toledo residents were ordered out of their homes overnight after a 5,500-gallon chemical tank leaked glycidyl methacrylate into the air — a toxic industrial chemical that burns eyes, skin, and lungs and can explode. Working families in a three-mile radius, including neighborhoods along the Lake Erie shoreline stretching into Michigan, were told to shelter in place, shut their windows, and hope for the best.

The leak started around 9:30 p.m. Tuesday at the MC Tank Transport terminal on Progress Avenue in north Toledo. By Wednesday morning, a massive plume hung over the city and residents reported burning eyes and throats. One sheriff's deputy who responded drove himself to the hospital after falling ill.

So what caused it? Ohio EPA spokesperson Bryant Somerville said the chemical leaked "because of an error that occurred when the material was being transferred," according to USA Today. That's it. An "error." No further explanation. A 5,500-gallon tank of hazardous, flammable chemical sitting in an industrial yard, and an "error" sent a toxic cloud over an American city.

The Ohio EPA is now on scene, according to WXYZ Channel 7 — after the fact, doing air tests to figure out how much poison residents are breathing. Toledo-Lucas County Health Department director Karim Baroudi was blunt: "It's really toxic if you touch it, if you ingest it. Now we're trying to kind of determine how much of a toxicity is in the air that the people are breathing so we can give better guidance."

That's the regulatory state in action: test after the cloud, advise after the exposure.

First responders and hazmat teams refused to approach the tank because of explosion risk. Mayor Wade Kapszukiewicz said there was a 12-hour window of potential explosive danger. USA Today noted that the mayor called it an "explosion" at his press conference, but city spokesperson Rachel Hart later walked that back, saying no explosion occurred. Either way, the tank is still emitting chemical gas and nobody's going near it.

Arkansas-based MC Tank Transport, which owns the tank, issued a statement saying its "immediate and overriding concern is the safety of area residents, emergency responders and our employees." Company reps were en route to Toledo, the mayor said.

Residents are left with questions. Kristine Kowalinski, who lives just outside the zone, told the New York Post she's worried about what rained down overnight: "My main concern is how did that affect everything overnight when it was raining down on cars, houses, my garden."

NBC News and ClickOnDetroit both reported that the fire department initially refused to name the chemical, while WXYZ reported the EPA identified it as an adhesive coating resin. Some outlets buried the Ohio EPA's admission that a transfer "error" caused the release; others omitted it entirely.

The pattern is familiar: a regulatory agency that exists to prevent exactly this kind of disaster shows up to monitor after the disaster is underway. No amount of air testing Wednesday morning undoes the exposure Tuesday night. The question isn't whether the EPA can test air quality after a toxic cloud blankets a city — it's why a 5,500-gallon tank of flammable, toxic chemical was being transferred with so little safeguard that a single "error" could send an entire community running.