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PROPOSAL: 

Draft Final Report of Multiple Air Toxics Exposure Study-II

SYNOPSIS: 

The Multiple Air Toxics Exposure Study-II project was initiated as part of the Environmental Justice Initiatives approved by the Governing Board in 1997. This comprehensive project, including a one-year field monitoring effort, emissions inventory update, and basin-wide modeling, has been completed. A draft report is being released to the public for a 90-day review and comment period.

Barry R. Wallerstein, D.Env.
Executive Officer

Background

In October 1997, the Board approved ten Environmental Justice Initiatives. Initiative No. 2 called for a major air toxics monitoring program, referred to as MATES-II (Multiple Air Toxics Exposure Study). This program is more comprehensive than a similar study conducted over a decade ago, in that there are more monitoring sites and a greater number of toxic compounds measured. MATES-II included two key elements: 10 fixed sites characterizing neighborhood-scale conditions over a one-year period; and a complementary microscale study using three mobile platforms to sample for approximately one month at each of 14 additional locations. The microscale sites were selected to reflect potential localized influences of toxic-emitting sources near residential neighborhoods. Eleven of the 14 sites were selected because of local stationary source influences, and the other three because of local mobile source influences. In addition to the monitoring, efforts were made to upgrade the toxics emissions inventories, and this information was utilized with computer simulation models to depict toxic risks for the entire Basin. In total, the MATES-II project represents one of the most comprehensive air toxics monitoring programs ever conducted in a major urban area in the country, and is being recognized as a model program.

Sampling began in April 1998, and concluded at the end of March 1999 for the fixed-site network. For the microscale study, monitoring continued into June 1999. It was intended that both programs be conducted simultaneously, but logistical constraints, such as getting local city permits and installing temporary power, often took weeks to complete. As a result, the last of the microscale sites extended beyond the completion of the fixed-site sampling. In total approximately 4,572 samples were collected during the course of the study, and 45,256 separate toxics analyses were made. Due to the large number of analyses needed for this effort, both AQMD and ARB laboratories shared the analytical burden. Staff is indebted to the ARB for its laboratory contributions.

Throughout the process, staff has been guided by a technical panel of experts. The Air Toxics Study Technical Review Group (ATSTRG) is comprised of 13 individuals, representing academia, environmental groups, industry and private sector consultants, and governmental agencies, including ARB, EPA, and the state Office of Environmental Health Hazard Assessment. A complete roster is given in Attachment A. AQMD staff is very appreciative of the time and effort spent by these participants in helping to improve the design of the study and providing timely suggestions as the project unfolded. ATSTRG members will review the draft report at the same time it is circulated for public comment. Staff looks forward to their insight and suggestions during the upcoming public review period.

The MATES-II program is a landmark study with important implications for future directions to reduce toxic air pollution in the Basin. Accordingly, staff believes the public should have an opportunity to review the document and data, and provide comments back to AQMD. At the time of the Board meeting, November 5, 1999, staff will make an oral report to the Board, and will make copies of the draft report available to the public, with a 90-day public review and comment period ending February 1, 2000, after which the report will be finalized. Staff will provide the Board with the final version of the report and a summary of the comments received.

Attachment A- ATSTRG Roster

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