HOUSTON -- After six months and $3 million worth of cleanup, the Houston Independent School district announced Monday that it will reopen Key Middle School after Spring Break, KPRC Local 2, Your Education Station, reported.

The school was shut down in September after several staff members and students complained of respiratory problems.

Critics claimed the school was filled with dangerous toxins, but a report by safety experts found that there were no unusual levels of mold inside the building.

While classes for Key Middle School students were held at nearby Fleming Middle School, crews tore out ceiling tile and replaced the old air conditioning system.

HISD said it has made extensive improvements, including pressure washing and painting, and purchasing new library books and textbooks.

"We've replaced the chiller. We've replaced the cooling tower. We've looked at piping and cleaned that out," regional superintendent Cynthia Wilson told KPRC Local 2. "We've going underneath the building to look at issues that were contributing to sort of a damp building."

Construction and renovation work will continue during Spring Break, and then classes will resume on March 26.

While some students and their parents are anxious to return to their "home campus," U.S. Rep. Sheila Jackson Lee said she is still concerned.

She wants the district to construct temporary buildings around the Key Middle School campus while workers continue cleaning and HISD continues to explore options for new construction.

"Do we really believe the floors are safe, the walls are safe, the marble is safe? Mold is very difficult and this was obviously a very dangerous condition as evidence by the Centers for Disease Control," Jackson Lee said.

But Wilson said, "We believe Key is ready to be occupied. I don't think we would send students and staff back if we were not confident that the building was safe to returning students and staff to work there."