Grand Island Senior High School students will have a few extra days of summer vacation.

Freshmen were supposed to head back to class Thursday, with upperclassmen returning Friday.

Instead, mold discovered in one area of the high school has caused district officials to postpone the start of the school year until Tuesday, the district said in a statement.

The school year will start on time for elementary and middle school students.

District officials said the decision to postpone the start of school was made after consulting with a scientist at a professional mold abatement company.

The mold is non-toxic, the district said, but it could cause allergic reactions in some cases.

The scientist told the district that the mold occurred because of "a perfect storm of unique weather conditions and high humidity in closed classrooms," the district said.

"He said these conditions are not normal, and likely caused this situation in as little as 48 hours," the statement said. "In other words, it is not a long-term situation."

The mold is in more than one classroom, Chief Financial Officer Virgil Harden told the Grand Island Independent. The mold problem, he said, was not caused by rain or other moisture getting in the building. There was no penetration of “what we call the building envelope,” Harden said. The mold resulted from indoor air quality issues.

When the mold formed, the air conditioning wasn’t on, and just a few people were using that portion of the building.

One room actually had 94 percent humidity, meaning it was a few percentage points away from raining inside, Harden said.

Harden hadn’t heard “even a whisper of any kind of a mold issue at Senior High” until Sunday, Aug. 4, when he a teacher emailed him.

The teacher had found “a dark smudge on a personal item in her classroom that she had left over the summer.” As Harden recalls, it was a pillow.

Administrators thought the issue had been taken care of until Monday, when more testing was done. The results came back Wednesday.

Inside the building, a process known as air scrubbing will proceed for 48 hours, beginning Thursday.

"Student safety is a top priority," Superintendent Tawana Grover said in the district's statement. "This is an unfortunate situation. Attendance is crucial, but we can not risk the safety of any students or staff."

This report includes material from the World-Herald News Service.

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