Presentation on benzo(a)pyrene

["Jon Dettling" <dettling@glc.org>]

Steering Committee,

As was mentioned previously, I gave a presentation last Wednesday to the
Great Lakes Binational Toxics Strategy Benzo(a)pyrene/HCB workgroup. The
slides and notes are at www.glc.org/air/Dettling_BaP_GLBTS_061206_notes.pdf.


The presentation went extremely well and the group was very excited to
receive this information. I'll summarize some of their key comments and
questions below. This group was formed in 1997 to implement and track the
progress of the benzo(a)pyrene and hexachlorobenzene "challenges" under the
Great Lake Binational Toxics Strategy, which are to achieve reductions in
releases of these substances within the U.S. (no amount specified) and to
achieve 90% reductions of amounts released within Canada. For the past many
years, they have been using the data from our project, in part, to determine
whether these targets have been met. One of the emphases of my presentation
was to strongly caution the group about the ability to make such conclusions
from our data. Because of the detail at which we have looked at the data as
part of the reassessment, I was able to give several specific examples of
why this is problematic and I think the message sunk in somewhat.

The majority of the presentation focused on the details of the original
inventory, the revised inventory and the changes that were made. For point
sources, they were pleased to see the FCCU emissions decrease substantially
in our revision. This group has looked into the issue of FCCU emissions
several times in the past and has concluded that facilities of this type
that are in compliance with the proper control technologies should have very
low BaP emissions (on the order of pounds or less). While ours are now much
lower, there are still two states reporting more than 1000 pounds from FCCU
processes (MI and PA). The group wondered whether further investigation
might result in these amounts being lowered also. 

Otherwise, the point source inventory was largely in agreement with
information they have received from other sources. It appears that metal
processing and coke ovens in particular are the major remaining facility
source and our revised data show this as well. I raised the issue of some
BaP likely being classified as "coke oven emissions" in the inventory. It
didn't appear that they had considered this previously, but seemed to agree
with the conclusion that it was probable. I think it would help our report
if we made a very preliminary assessment of this. For example, if we could
get a reasonable range of how much coke over gas is BaP, we could include a
high-low range of how much "additional" BaP is in our inventory in that
form.

For area sources, they were very pleased to see the improvements being made
in terms of how many states are estimating some of the major
BaP-contributing categories. Open burning, residential wood combustion,
commercial cooking and others all have more states estimating these now than
prior to the revision. 

For mobile sources, there was some surprise among the group that diesel
engines were such low contributors to the overall emissions. It appears that
they have seen some receptor-modeling results in the past that suggested
that diesel engines were a very large contributor (e.g., >50%) to b(a)p.
This definitely contradicts our data, which has them at <1%. I expressed my
belief that the quality of the on-road and non-road inventories is probably
very good relative to other aspects of the inventory and that it's unlikely
that diesel contributions are being largely underestimated. They also raised
some questions about how the diesel fuel regulations that are being
implemented in 2007 might affect BaP emissions. I don't know if this
information exists. Does anyone know if such tests have taken place? In
terms of inventory preparation, this won't really be a concern until the
2008 data.

Like I mentioned above, there was some very good discussion on the use of
the inventory for assessing "trends." It's clear that a comparison of our
revised 2002 data to that from previous years would not reveal anything
about the actual trends of emissions when looked at from the level of a
regional total. The same generally applies to prior years, as changes in
methodology frequently take place. Although I think the group agreed with
this after seeing the data in great detail, I get the sense they are not
left with many other options and therefore may revert to using our regional
total data to show trends. I think it may be helpful if we used our report
as a place to offer a qualitative assessment of some things that would have
affected BaP emissions over the past 10-15 years and gave a general range of
the likely magnitude of changes. For example, we could look at dates for key
MACT implementation, such as for FCCUs, dates for the introduction of
certified woodstoves, etc. Because the GLBTS BaP challenge for the U.S. is
only qualitative (i.e., achieve reductions in . . .) but doesn't specify a
quantity, I think this type of analysis would be very useful for them in
that it would allow them to make a statement that the challenge has been met
without having to misconstrue our numbers.

As I said above, our work was very well received by their group and I think
they will find our final report very valuable in their work. I hope to get a
revised draft of the report out to the group before the holidays. If people
have questions or comments on any of the above, we can discuss more on
Wednesday.

Jon

______________________
Jon Dettling
Great Lakes Commission
734-971-9135
dettling@glc.org


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