Superintendent of Schools Carlos Colley reported last Wednesday that readings in only two rooms now exceed the federal Environmental Protection Agency’s acceptable standard of 300 nano grams per cubic meter for the known carcinogen.
In September, tests revealed that airborne PCBs exceeded the EPA standard in nine rooms at the school.
Air in the two rooms still in violation has improved somewhat but still does not meet standards, Dr. Colley said.
A second floor guidance office that is not now being used improved from 630 nano grams per cubic meter to 530. Room 255, a storage room, improved from 640 nano grams to 600.
At the special meeting, the superintendent told the school committee that the entire school is cleaned on a two-week cycle. The worst reading, he said, were in areas that had gone the longest without cleaning.
Supt. Colley said that the testing will continue and added that no students or staff spend time in the rooms with high readings.
The Westport Board of Selectmen recently signed a voter-approved a 19-year loan for $4.3 million to pay for PCB removal and unrelated green repair work at the middle school.
The 19-year loan has an annual average interest rate of 2.78 percent with interest expected to total over $1 million.
In the middle school, the substance was found during the summer of 2011 in window caulk that subsequently leached into surrounding masonry over the years and eventually into the air inside the school. PCBs were also round in the glue used to secure roof panels at the school.
That caulking work apparently dates back to the 1970s before the use of PCBs was banned in 1979.
The town spent around $3.4 million removing and replacing all known caulk and sealants containing PCBs and also replaced masonry near contaminated windows.