Chun Yi, You raised the issue of MDI emissions at the Toronto meeting and passed out an article describing efforts done at the national level to correct what were believed to be substantial overestimates of these emissions in the NEI. I've taken a look at the article and have done a query on our 2002 data (attached) to see what our emissions look like. There are about 50 sources in the inventory with emissions of more than 100 lbs, including a handful with emissions of several to 100 tons. In addition, there are about 100 more sources with emissions of 10-100 lbs. The information in the article suggests that the sources of more than 100 lbs. are almost certainly over-estimates and those of 10-100 lbs. may be overestimates also in many cases. The issue was raised at the meeting of how relevant this pollutant is to address, especially regarding deposition to the Great Lakes. Using the PBT Profiler (www.pbtprofiler.net), it appears that the compound in moderately persistent and moderately bioaccumulative. It shows a tendency to partition to soils and sediments, where it has a half-life as high as about a year. As HAPS go, it appears to be in the mid-range between those that are very relevant for deposition to the Great Lakes (e.g., dioxins) and those that aren't (e.g., benzene). I think given the clear evidence presented that our emission for this compound are likely much too high, it may be worthwhile to attempt to correct some of those emissions if it is feasible to do so. In particular, there appear to be some "low hanging fruit" for which applying corrections would significantly decrease (and presumably make more accurate) the total regional emissions. We've often encountered difficulty in correcting facility emissions and it's difficult to make these corrections permanent, as facilities will often re-report the high numbers each year. The article you passed out mentions a "worksheet" tool that can be used to estimate emissions, however I can't find this on the EPA's website that is referenced. Do you have any recommendations as to how to go about examining our data further and possibly making corrections or about how to incorporate this information into future years' inventories? We can discuss this as a group on Wednesday's call and see what the thoughts are from the rest of the team. Can you scan the article you have and send an electronic version for anyone who wasn't at the meeting? I could scan mine, but most of the tables are very dark and hardly legible in my version already. regards, Jon ______________________ Jon Dettling Great Lakes Commission 734-971-9135 dettling@glc.org
Attachment:
MDI.xls
Description: MS-Excel spreadsheet