Image: Google Maps
Passers-by were worried by police and fire activity after a suspicious substance report Monday. (Location is approximate.) Image: Google Maps

A report of a suspicious white substance in the 1900 block of Martin Luther King Jr. Way closed a central Berkeley block during a short investigation that caused alarm among neighbors and passers-by Monday evening.

The Berkeley Fire Department ultimately determined that the substance was actually plaster from a resident’s home, authorities said.

Monday at 5:36 p.m., dispatchers received a call from a man who had noticed “white powder in various places around his house,” said officer Byron White, a Berkeley Police spokesman. The man had seen the material in his side yard two days prior.

The man cleaned up the powder but later noticed what appeared to be a rash, which made him worry that the substance had been hazardous, said Deputy Berkeley Fire Chief Avery Webb.

Police officers responded to the scene, and called for firefighters to investigate the substance, said White.

Authorities blocked the roadway at 5:42 p.m. around Hearst Avenue. At least one local business owner was told to shelter indoors during the investigation.

Webb said a fire engine, ambulance and battalion chief were sent to the scene to investigate, and ultimately determined that the substance was sodium carbonate, or plaster.

The Fire Department did not activate its hazardous materials team, which includes four hazmat specialists, because first responders were quickly able to determine that the substance was not a threat, Webb said.

The department also has an agreement with Alameda County firefighters stationed at the Lawrence Berkeley National Laboratory who can be called in if additional resources are needed.

Webb said initial reports about hazardous materials determine what kind of response to dispatch.

“It’s not unusual for something to sound like it might potentially be a hazardous material,” said Webb. “If there are several people down, with reports of choking or vomiting, when you hear something like that, the response is a lot different. We triage the report that comes in and come up with what seems like an appropriate response. But we always have the ability to upgrade the response if necessary.”

The scene was deemed clear at 6:14 p.m. Due to the central location of the incident and the closure of the block, many readers wrote to Berkeleyside to ask what had happened.

White said a lieutenant from the Police Department was monitoring the situation, and that a sergeant and four officers were initially dispatched to the scene. He said that is a typical response to a that type of call.

White said police work closely with the Fire Department during these types of incidents. Police work to secure the block and help with evacuations if they are need, but otherwise Fire Department safety protocols govern the scene.

White said that anytime a suspicious substance report comes in, authorities take it seriously.

“We have to take it seriously until it’s proven otherwise,” he said. “Until we know that, we assume the worst.”

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Emilie Raguso (former senior editor, news) joined Berkeleyside in 2012 and covered politics, public safety and development until her departure in 2022. In 2017, Emilie was named Journalist...