Our Recent CEP and Chemical Sources Web Maps for
SVTC and a "Tad" about Web Maps in General

Cumulative Exposure Project (CEP) Data Background
CEP Data and Mapping for SVTC
SVTC Toxic Chemical Sources
Limitations of Image-Map Based Web Maps
Virtues of Image-Map Based Web Maps
Real GIS Mapservers?
Our Other Web Map Projects
View the New Maps

Below you will find a very brief description about our work and how we created the SVTC Web Map project. Also, there is a more general discussion of Web Map technology and application.

Cumulative Exposure Project (CEP) Background
I became interested in the CEP data last October. I have done a good deal of
environmental justice research and have always been frustrated knowing that no matter which data source I used, I was only capturing a very small amount of the real pollution "out there" and I never knew for sure whether pollution released by a facility had the greatest effect on its nearest neighbors or those elsewhere. The CEP data promises to relieve this frustration.

Ideally, every community in the U.S. would have multiple air monitors that would sample the air continuously for the thousands of toxic chemicals that we breathe. We don't have such a system. What we do have is a handful of air monitors scattered around the country, predominately in the most urban areas. We also have an Environmental Protection Agency that collects large quantities of data from thousands of industrial facilities around the countries. The folks at EPA in the Cumulative Exposure Project have combined the air monitoring data with the facility data and employed a sophisticated modeling program to determine the modeled concentration of each Hazardous Air Pollutant (HAP) for each of the 66,000+ census tracts in the U.S. Their own preliminary tests indicate that these modeled results are very close to those found in our communities in-real-time and that they tend to underestimate true concentrations. We encourage you to visit their website and learn as much as possible about this new data product.

In March 1999, after EPA kept moving up their deadline for the release of the data, I filed a Freedom of Information Act (FOIA) request to obtain the data. EPA had decided not to place the data on their website because industry and air quality boards had complained that it was based on old data and would not reflect the improvements they have made in recent years. They urged EPA not to release it until the model was run with more recent data. EPA is doing this now and have said that they will release the new, more current data at the end of this year. One reason for my desire to obtain this data was to enable me to compare it to the new and improved data and determine whether our air quality is indeed improving as industry and the air quality boards claim.

This will be very interesting. Recently Representative George Miller completed a study of 4 bay area counties using real-time (NOT modeled) data and found that the sum of (only) a handful of cancer-causing chemicals in the air breathed by bay area residents are (remember this is not a model!) 208 times higher than the Clean Air Act goal! Similarly, Representative Henry Waxman found that in Los Angeles County, a small handful of cancer-causing chemicals were present in the air of Los Angeles county at a concentration 426 times the Clean Air Act goal.

CEP Data and Mapping for SVTC
Once we completed the Toxic Chemical Source maps for SVTC (below), we asked if they would like me to review the CEP data I'd recently received (as a result of my FOIA request) and apply it to Santa Clara County. We spent approximately 120 hours sorting and comparing the data, producing five (5) CEP maps and twelve (12) accompanying demographic maps - a very preliminary look at the data. We found during this very limited analysis that the modeled CEP concentrations of HAPs associated with cancer risks in Santa Clara County range from a low of under one hundred (100) times the Clean Air Act goal to over one thoudsand, five hundred (1,500) times this goal. There are NO areas in Santa Clara County that have modeled concentrations even close to the Clean Air Act goal. This, of course, should not be a surprise after seeing the Miller and Waxman reports that are not models, but based on real-time and very recent data from air monitors.

We encourage you to take a look at the CEP Maps and Links and see for yourself. Also, be sure to read EPA's disclaimer. You may also wish to explore EDF's new Hazardous Air Pollutant website which is based on the CEP data.

Our current plans include doing a more comprehensive analysis of the CEP data for our own county, Santa Cruz. This research will look at cancer-risk concentrations as well as the chronic and acute effects of the HAPs.

Creation of SVTC Toxic Chemical Sources Web Map Project
Several months ago we were contacted by Silicon Valley Toxics Coalition (SVTC) and asked to create a Web Map project that indicated the locations of various toxic chemical sources in Silicon Valley (Santa Cruz and Santa Clara counties and portions of Alameda and San Mateo counties). The information, along with the longitude and latitude (for mapping purposes), was obtained from the Landview III data, available free at RTK Net. We created one thousand, one hundred and thirty-eight (1,138) maps for this project.

Rather than use a true GIS server, similar to the Community Service Map Server we created for Cruzio, our local internet service provider (ISP), SVTC opted to use image-maps. I have provided a summary of the virtues and limitations of both image-map based, and true GIS servers below. Note that the majority of the work for these projects is not in creating the maps, but in gathering the data and preparing it for use. The above SVTC project took approximately 180 hours to complete. Much of this time was devoted to data work. Try it out, you'll like it.

Limitations of Image-Map Based Web Map Projects
Until now, image-maps as the basis of an interactive Web Map project had several limitations. The project, once created, was difficult and time consuming to edit and update. A visitor was unable to "pan" (navigate left or right, up or down). Some of our earlier image-map based projects are the
Santa Cruz Toxics Release Inventory and the Environmental Defense Fund Chemical Scorecard.

Virtues of Image-Map Based Web Map Projects
Image-map based Web Map projects also have their virtues. The images load very fast compared to MOST GIS servers (see below for more about GIS servers) and other internet mapping schemes. They do not require that any special, and sometimes costly, software licenses be obtained, and no special software has to be installed on the web server. Over the last year we have developed a system with our partner,
Light in the Attic, that allows for multiple zoom levels, panning at any zoom level, multiple live ("clickable") point categories, and editable html templates. We have ended up with a very GIS-like Web Map project creation tool that is readily updated and loads images very quickly. If you want to create web map projects like these contact Aran Meuser at Light in the Attic for the best (and possibly the only) tool in the world for the job.

Real GIS Servers?
GIS internet servers have been more hype than functional reality. I have yet to find one that works well enough to keep the average visitor interested. Even the supposed top-of-the-line GIS servers from the most well known GIS firms fall flat. Less costly alternatives, such as Java Mapplets suffer a similar fate. We finally discovered
Caliper's GIS server. We have had excellent experience with their products, using Maptitude for all of our GIS work. In fact, we turned to Maptitude rather than using some of the other more well known products because of its very high speed and ability to handle extremely large map-data sets, low-cost, ability to import and export in almost any geographic data format, and it comes with tons of free data.

Using Maptitude as a base, we spent several hundred hours and developed an extremely fast, efficient, and robust GIS Mapserver. Unlike other GIS Mapservers, this one works in REAL-time! Give it a try. You'll find that it loads images nearly as fast as image-maps. The server has been running at this site for nearly a year and has never failed. We also developed an administrative system so that points and layers can be added, data changed, and points moved all through password-protected web pages - instant updates on-the-fly.

If I can be of any help to you with your data or mapping needs, please send email to [email protected].


Michael R. Meuser,
Environmental Sociologist

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