[50372] in Hotline Meeting
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daemon@ATHENA.MIT.EDU (Andrea Nichols)
Tue Mar 21 07:12:42 2000
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From: Andrea Nichols <andrea@PLANT.MIT.EDU>
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Date: Tue, 21 Mar 2000 07:12:27 -0500
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At approximately noon yesterday (Monday, 3/20), the Industrial Hygiene
Office (IHO) received a call from an employee in the MIT Federal Credit
Union (E19-437) who was concerned about an odor which had become noticeable
about 15 minutes earlier at that location. She reported that it was a
"glue-like odor", and requested that IHO evaluate the air quality.
I proceeded to Bldg. E19 with a mini-RAE photoionization detector (PID), an
air sampling instrument capable of detecting a broad range of organic vapors
and providing an estimate of the cumulative loading of organic vapors in the
air. Upon exiting the elevator on the fourth floor at the E18 end of the
building, there were low but definitely detectable levels of organics (<5
ppm). The odor became more noticeable at the Main Street end of the
Building, and the Credit Union workers identified the construction area at
that end of the 3rd floor as the likely location of the emission source.
Indeed, the odor was much stronger and the PID readings higher (25-35 ppm)
in the hallway outside the 3rd floor construction area, and once inside Rm.
339 the measured levels continued to rise dramatically. An open one-gallon
container of Lacquer Thinner was found (and capped) and a spray can of Glass
Cleaner was also observed in the area with the highest PID readings. Two
workers in the area said that they had been using the materials
(particularly the Lacquer Thinner) to remove the plastic film that was on
the interior of the windows in that area. I requested that they stop all
chemical use until I could discuss this work practice with the contractor
supervisor (Jim Dumont).
A search of the 2nd and 3rd floors of the building failed to turn up Jim (it
was lunchtime), so I went down to the Operations Center and requested that
the outside air dampers be set at maximum opening for the air handling units
which serve the 2nd, 3rd and 4th floors. That was done. (Actually, one unit
serves floors 2 & 3, while another serves floors 4 & 5). Before I left the
building, I returned to the Operations Center and requested that those air
handlers be operated in this mode until 4 pm.
Upon returning to E19-339 to ensure that the work had stopped, I saw Joe
Collins (the MIT Project Manager for the job) and informed him of the
complaint, the chemical sources, and the steps that had been taken. He did
not object, nor did he offer any alternatives.
Finally after 1:00 pm I found Jim Dumont, the contractor supervisor, in
E19-339. I related my activities of the previous hour, and Jim agreed with
the measures that had been taken. Only a small number of windows remained
with the film in place, and Jim ordered the two workers to use vinegar and
razor blades to loosen and remove the film. This had been the procedure
that had been used on the window film in Rm. 338, and that work had been
completed without incident.
After my meeting with Jim, I made one final sweep of floors 2-4 with the PID
to see if the ventilation was effective in reducing the levels of organic
vapors. At the location of chemical use within Rm. 339, levels had dropped
from 100-200 ppm to the range of 40-50 ppm. Immediately outside the work
area in the hallway, levels had dropped from 25-35 ppm to 12-15 ppm. In the
Credit Union office, noontime readings of 3-4 ppm had dropped to 0.5-0.8 ppm
by 1:20 pm. Residual vapor levels on the second floor (by Personnel) were
slightly higher than those observed on the fourth floor (5-10 ppm), but this
was expected since the air handler serving the work area where the chemicals
had been used also serves the second floor.
At no time after my arrival at E19 did I feel that the evacuation of any
portion of the building was warranted. The chemical usage had been stopped
and the ventilation systems were operating at maximum outdoor air and
minimum recirculated air. The Lacquer Thinner is a hydrocarbon mixture
which does contain toluene as one of several ingredients. Toluene has a TLV
(the exposure criterion based on health risk) of 50 ppm as a day-long
average. Toluene was only one of several chemical vapors (the others being
less toxic) contributing to the PID readings which were observed, so there
was no chance of overexposure to anyone outside of E19-339. For that
matter, once the work was stopped and the ventilation rate increased, the
workers in 339 were at no significant risk either. I did advise the
original caller from the Credit Union that spending lunchtime away from E19
would permit dilution and removal of the air contaminants by the air
handling systems and hopefully eliminate the odor at that location by the
time of her return.
If there are any questions regarding the incident or my accounting of it,
please direct them to me.
Regards,
Bob Clifford
MIT Industrial Hygiene Office
253-0908 or 253-2596
