Classes have been moved out of a portable unit at Lawrence’s East Heights School after inspections revealed excessive moisture levels and the presence of mold within the unit’s walls, district officials announced late Friday.

Media members were notified of the issue the same day that inspectors discovered a small — but otherwise unspecified — amount of mold inside the portable unit, which had housed four classrooms, library media and other resources since August.

The former East Heights building (the one-time elementary school, 1430 Haskell Ave., shuttered more than a decade ago) has served as a temporary home this year for students and staff displaced by continuing renovations at Pinckney Elementary School.

The portable unit in which mold was found had been in use by Pinckney students and staff since the beginning of the school year, said district spokeswoman Julie Boyle.

“While recent air quality sampling indicated normal levels of indoor airborne mold spores as compared to outdoor samples, in the interest of student and staff safety, the district is vacating and replacing the leased portable,” the district said in a news release Friday. “Pinckney has informed its school community of the issues with the portable and this decision.”

Reports of a roof leak on the unit Sept. 14 prompted an investigation into moisture levels inside the unit, according to the release. During repairs, the district contracted with META Consulting to conduct air quality sampling, which took place the next day, on Sept. 15.

Testing indicated above-normal levels of airborne mold spores in two of the unit’s six rooms when compared with outdoor samples. However, a follow-up report from META Consulting, the district said, advised that mold spores are found almost everywhere, and, while it’s “impossible to eliminate mold and mold spores,” indoor mold growth can be reined in by controlling moisture levels.

District facilities staff then made a series of repairs to the unit, including replacement of damaged ceiling tiles, subfloor, carpeting and window trim, and sealing of windows and exterior seams, as well as removing any visible moisture.

Classrooms were moved elsewhere during the repairs, and no visible moisture issues were found afterward, the district said.

A second round of air quality sampling, conducted by APEX Environmental Consultants on Sept. 29, however, indicated that the moisture level within the unit’s walls could signal “a hidden potential for mold growth,” according to the district’s news release.

The APEX report indicated that both the north- and south-facing exterior walls were wet, with meter readings of 100 percent relative moisture content “in most areas.”

“Our Facilities and Operations staff performed a visual inspection on September 30, and returned on October 1 with the supplier of the portable unit to remove two exterior panels at random, one from the north side and one from the south side,” Boyle wrote in an email. “They found dry walls with no visible signs of mold.”

APEX’s report at the time also noted normal levels of indoor airborne mold spores “in all areas as compared to outdoor samples.”

Roughly two weeks later, based on evaluation of that report, district staff returned to the portable unit, this time for a more thorough assessment of the structure, with the unit’s supplier, an APEX environmental consultant, and professional restoration and remediation specialists in tow.

On that day, last Friday, they removed exterior panels, conducted a systematic investigation of the condition of the walls and discovered “excessive moisture levels” and the presence of mold within the unit’s walls.

Boyle said no evaluation of mold levels had taken place that day, but that staff described the amount found as a small, isolated growth, which was enough to prompt officials to vacate and replace the unit.

“Additional testing wasn’t necessary since we were vacating and replacing the portable,” Boyle wrote in an email.

Mold exists pretty much everywhere and cannot possibly be eliminated entirely from indoor environments, the U.S. Environmental Protection Agency notes. It has also been capable, no matter the variety, of negatively affecting the health of those who come into contact with it.

Exposure to mold can lead to allergic reactions or even asthma attacks in people who are allergic to it, according to the EPA, while some molds can produce potent toxins and/or irritants.

The portable unit at East Heights has not been in use by students since last Thursday, Boyle said. District officials anticipate moving classes into a new unit by Nov. 28.

In the meantime, the fifth-grade and third-grade classes that previously occupied the unit have been relocated to classrooms within the East Heights building.

The unit had been in use at East Heights since fall 2014, Boyle said.