According to a report released this month, the air of 23 buildings was tested on a portion of Moffett Field where the United States Navy is responsible for the pollution cleanup. Two occupied buildings had toxic vapor levels above EPA limits in areas where people work: the Moffett Field history museum and Moffett's Building 10, which houses a crew of building maintenance workers.
Several other buildings also had elevated levels of toxic vapors in single locations not occupied by workers. Those buildings include the NASA Ames convention center and cafeteria, the Moffett Field Commissary — where members of the military buy discount groceries and other items, and two large research lab buildings, N239A and N210.
A maintenance worker in Building 10 — where trichloroethylene vapor levels were 10 times the EPA limit — said employees there were told little about the situation when it was found. About 20 employees spend "an hour a day" in the building five days a week, he said. It also houses boilers to steam-heat Moffett's buildings.
"They just come here to grab their tools and eat their lunch," he said, adding , "They didn't tell us anything" about whether it was safe.
The report comes as the Navy proposes the use of new technologies to clean up the groundwater plume it left at Moffett where thousands of pounds of various solvents were dumped or leaked into the ground over several decades. The primary chemical, trichloroethylene (TCE), is known to cause cancer from years of exposure, birth defects from just weeks of exposure and a slew of other health problems, according to the EPA.
The danger at Moffett comes when the vapors from the ground rise through floors and collect inside buildings. The EPA says the area's water supply is not affected.
It's unclear how long workers were exposed to TCE at building 10, where a steam tunnel opening in the floor allowed vapors collected from the plume into the building, probably for years. Tests found extremely high levels of TCE and perchloroethene (PCE) in the steam tunnel, 960 micrograms per cubic meter of TCE and 770 for PCE.
The EPA's toxic vapor limits for a workplace are 5 micrograms per cubic meter for TCE and 2 for PCE, levels designed to protect against cancer from decades of exposure when workers are exposed during a full work week.
At Building 10, installing a temporary ventilation system and sealing off of the steam tunnel reduced the vapor levels below EPA limits a month after they were found in May of 2012, the report says.
At the museum, air tests in work areas found TCE below the limit (as high as 3.1 micrograms per cubic meter) but did find PCE above the limit (as high as 4.4 micrograms per cubic meter) in four of five air sampling locations. PCE — commonly used as a dry-cleaning solvent — can cause kidney and liver damage as well as cancer, according to the EPA.
In building N210, NASA's Flight Systems Research Lab, tests found one location with toxic vapors above the limit, 17 micrograms per cubic meter of TCE under a raised floor of two office cubicles in room 145, after a separate ventilation system used to draw the vapors from under the raised floor had been shut off for a weekend. At building 239A, the Life Sciences Research Lab where animals are and plants are subjected to tests in centrifuges, only a hallway had elevated toxic vapors, 6.8 micrograms per cubic meter of TCE in hallway C102 — but only with the building's ventilation system off.
At the NASA Ames conference center, toxic vapors were found above the limit in one location, a "utility conduit" to a crawl space under the floor of room 105A, with 7.9 micrograms per cubic meter of TCE. TCE vapor levels in work areas were below EPA limits, but were as high as 3.9 micrograms per cubic meter.
At the commissary, 13 air samples were taken throughout the building. TCE was found in work areas at the same levels as outdoor air, while samples were slightly above outdoor air levels for PCE. The highest level, 6.1 micrograms per cubic meter of TCE, was found in the crawl space under room 110. The report notes there is a crawlspace under the entire building.
Strangely, TCE was was below cleanup levels in both the commissary and the conference center with heating and ventilation systems off, indicating a problem with the HVAC systems in each building, Neither building has systems to keep toxic vapors out of the buildings.
The outdoor air at Moffett was also tested. In 29 air samples, TCE was found as high as .24 micrograms per cubic meter and PCE as high as .21 micrograms per cubic meter.
The report says all six of the buildings will require a long-term program for regular air sampling and "engineered remedies" to keep toxic vapors at bay.
Michelle Le contributed to this report.