The ATDA (Air Toxics Data Archive) web site is sponsored by the STAPPA/ALAPCO/USEPA Air Toxics Monitoring Subcommittee and is part of the work to support the deployment of a national air toxics monitoring network.
The purpose of this web site is to provide users with the capability to browse and query existing air toxics monitoring data. Such analyses of these data will provide information about the spatial pattern, temporal profile, and general characteristics of various air toxic compounds.
Background
The U.S. Environmental Protection Agency (USEPA), in concert with state and local air pollution control agencies, is developing a national air toxics program designed to characterize, prioritize, and equitably address the impacts of hazardous air pollutants (HAPs) on the public health and environment. One of the major activities in the national program is a National Air Toxics Assessment (NATA), which includes expanded air toxics monitoring, improving and periodically updating emissions inventory, national- and local-scale exposure modeling, and continued research on effects and assessment tools. The three purposes for the expanded monitoring are: (1) characterize ambient concentrations and deposition in representative areas; (2) provide data to support and evaluate dispersion and deposition models; and (3) establish trends and evaluate effectiveness of HAP emission reduction strategies.
Data analysis is a necessary component of every air monitoring program. Air toxics data do not have value unless they are quality assured and then analyzed in the context of the overall NATA. Adequate resources must be allocated for data management, data reporting, implementation of statistical quality assurance procedures, data management, and data assessment. To this end, of the $3.0 million in section 103 funds appropriated for the first year of national air toxics monitoring activities, $0.5 million will be used to support the analysis of existing (and any new) national, state, and local air toxics monitoring data. The remaining $2.5 million will be used to support four urban area and six small city/rural pilot monitoring projects. For more information on the pilot monitoring projects, see “US EPA FY2000 State and Local Agency Grant Guidance and Allocation: National Air Toxics Monitoring Pilot Program”, April 26, 2000. The data analysis plans are discussed below.
The data analysis project is intended to “mine” the existing data to provide information about the spatial pattern, temporal profile, and general characteristics of air toxics compounds. The project is managed by representatives from LADCO, NESCAUM, and CARB. On November 2, a contract was issued to Battelle Memorial Institute and Sonoma Technology, Inc. to conduct this work. On December 1, Battelle delivered the final technical work plan.
Project Plan
The six tasks in the work plan are as follows:
Task 1: Compile central database, including updating USEPA’s air toxics data archive
In mid-October 2000, ICF Consulting (under contract to USEPA) delivered an updated version of the data archive. Battelle prepared a “table of contents” for the archive in February 2001. Battelle will obtain additional data from a few agencies.
Task 2: Assessing quality of existing air toxics data
Battelle will assess the data completeness, examine appropriate quality assurance data and establish data quality ratings, and examine measurement precision. Based on this work, Battelle will provide preliminary recommendations on sampling/analysis methods.
Task 3: Prepare data for analysis, including developing a queriable, web-based system
Battelle will develop a simple, workable web-based system which can produce user-requested tabular and graphical summaries of the data. LADCO will host the web site initially.
Task 4: Perform interpretative analyses of existing air toxics data
Battelle and Sonoma Technology will perform a number of statistical and graphical analyses to address issues such as sampling frequency, spatial variability, temporal variability, emissions patterns, urbanicity, trace metal composition, compound comparisons, and minimum detection levels (MDLs). The analyses will tentatively focus on the following nine compounds:
VOCs (benzene, 1,3-butadiene, chloroform, tetrachloroethylene)
Carbonyls (acetaldehyde, formaldehyde)
Metals (cadmium, chromium, lead)
Battelle will also prepare a short report on recent studies related to assessments of air toxics concentrations.
Task 5: Update data archive and data analyses to include data from monitoring pilot project
Many of the analyses planned as part of Tasks 2 and 4 will be repeated with pilot city data. The design of the monitoring pilot project will allow several additional analyses, including sampling and analysis precision, sources of variability, MDLs, elemental carbon v. diesel emissions.
Task 6: Reporting
In addition to the various reports identified below, monthly conference calls will be held during which Battelle will review the work completed during the past month, the project budget, and plans for upcoming work.
The current schedule for this project is as follows.
July 2001: Deliver preliminary draft data analysis report and updated web-based system
Aug 2001: Deliver updated draft data analysis report and updated web-based system
Aug 2002: Deliver draft final report and updated
Oct 2002: Deliver final report
To supplement Battelle’s data analysis work, ICF Consulting was hired to analyze air toxics modeling data. ICF will examine the spatial, seasonal, daily, and diurnal variability of air toxics concentrations (for benzene, 1,3-butadiene, tetrachlorethylene, formaldehyde, and lead) based on two modeling studies, including USEPA’s recent ASPEN modeling performed as part of their National Air Toxics Assessment. ICF will provide recommendations on network design based on their analysis of the modeling data (and monitoring data) for Houston and two other cities (Baltimore and Minneapolis). In addition, ICF will address how states and locals can use the ASPEN modeling (in conjunction with other information) to help design air toxics monitoring networks.