902 PCBs AND ASSOCIATED AROMATICS
PCB Degradation in Building Fires The formation of
pyrolysis products will ultimately depend upon factors such
as the following:- the time that the askarel mixture is at a temperature
which allows a reaction yield of significance, - the volume and surface area of droplets of askarel
emitted in an eventful failure, - the availability of oxygen and
- the effect of soot particles on the dissipation of
heat and the availability of oxygen.
Real-world experience has shown that the eventful failure of
electrical equipment can be all too frequently catastrophic.
In particular, it is irrefutable that transformer fires do pro-
duce askarel oxidation products in significant quantities. As
discussed earlier, studies have indicated that the breakdown
of askarel transformer dielectric systems due to multi-stress
aging may produce toxic products at concentrations of con-
cern. The yield and distribution of products can be expected
to depend upon the availability of oxygen. The major quan-
tity of toxic products will undoubtedly be derived after the
failure of the transformer has resulted in a fire situation.
When a transformer is retrofilled to 500 ppm PCB,
one would expect that the rate of conversion of PCBs
would be very much less than in the case of an askarel fire.
It becomes increasingly less probable that a large enough
quantity of pyrolysis products would be produced as the
concentration of PCBs and chlorobenzenes is reduced.
These qualitative expectations were realized when a fire
occurred in the basement transformer vault of the ElectricalEngineering laboratory of the University of Manitoba in- The six transformers involved in the fire contained
mineral oil contaminated with 250 ppm PCB. An electrical
failure caused one of the transformers to arc and catch fire.
All six transformers were damaged. During fire- fighting
attempts a transformer exploded and distributed PCB
contaminated soot onto the walls. No PCDFs were found.
PCDDs, which are typically formed at an order of mag-
nitude less concentration than PCDFs, were not detected
either.
The fire which occurred on February 5, 1981 in the
Binghamton State Office Building in Binghamton, New York,
involved a PCB filled transformer located in the basement. It
has been estimated that between 50 and 100 gallons of PCB
dielectric fluid were involved in the fire. The building was
closed and sealed shortly after the fire and remains closed
today in 1996. PCBs and oxidation products were distributed
throughout the 18-story structure via two ventilation shafts.
Analysis of soot samples revealed high concentrations of
PCBs, PCDFs, PCDDs and also other classes of toxic chlori-
nated aromatic compounds (Table 34).
The concentration of compounds of concern in the
soot particles varied between floors in the building. A com-
posite sample was analysed and found to contain three orders
of magnitude more of 2,3,7,8-TCDF (270 ppm) and 2,3,7,8-
TCDD (2.8 ppm) than fireplace soot. The average PCB con-
centration in the air was 1.48 μ g/m^3 while dust samples in the
spaces above ceilings averaged 1,995 μ g/m^2.
Exposed horizontal surfaces in offices had 162 μ g/m^2
while vertical surfaces and walls had about 7 μ g/m^2. PCB
contamination was found inside closed filing cabinets and
TABLE 34
There is a growing list of major PCB-related fire incidentsLocation DateToronto, Ontario, Canada December 1977
Boston, MA (Saniford Street) October 25, 1981
Boston, MA (Hancock Building) February 1983
Boston, MA (Quincy Market) January 14, 1980
Binghamton, NY (BSOB) February 5, 1981
Pittsburgh, PA (Main Post Office) September 4, 1981
Tulsa, OK (Beacon Building) December 29, 1983
Jersey City, NJ (Railway) June 2, 1982
San Francisco, CA (One Market Plaza) May 15, 1983
Chicago, IL (First National Bank) September 28, 1983
Syracuse, NY (Chimes Building) December 21, 1983
Jacksonville, FL (American Electric) January 29, 1984
Miami, FL (New World Tower) May 29, 1984
Duval, FL (Country Courthouse) June 5, 1984
Florida (J.C. Penney) September 4, 1984
Montreal (Hydro Quebec Research Lab.) November 20, 1984
Grand Basile, Quebec, Canada (Warehouse) August 23, 1988
New York, NY March 4, 1990C016_003_r03.indd 902C016_003_r03.indd 902 11/18/2005 1:12:38 PM11/18/2005 1:12:38 PM