Web GIS Applications
A growing number of spatial data tasks can be accomplished with web GIS applications. These include applications that work through your web browser, like Google Maps, through freely downloadable software, like Google Earth, or through specialized web mapping sites, hosted by specific sources, like the National Library of Medicine’s TOXMAP. To generate a map or identify locations of the facilities regulated by the EPA, and included in the Toxic Release Inventory, you have multiple choices of web-based applications. Some of these include the EPA’s TRI Website, TOXMAP, ArcGIS Online, and Google Earth.
On the front page of the EPA’s TRI Website
, you can access information on regulated facilities in the “Learn about Toxic Chemicals in Your Community” map. By submitting address information, the map zooms into the area entered and flags nearby facilities. Clicking on the facilities will retrieve more information, such as the name of the facility, and updated records of the releases for that facility.
is an online GIS application that allows you to investigate TRI facilities across the country, types of releases by facility, changes in releases over time, and the relationship between facilities and other demographic and health correlates. TOXMAP is hosted by the National Library of Medicine
and integrated with databases on the health effects of toxic releases. A tutorial
on how to identify and interpret information on TOXMAP is posted.
The company ESRI hosts a website called ArcGIS Online
, which allows you to create your own maps, like this one
, using web services or by uploading data that you have. There is a great deal of flexibility in producing the map that you desire. The existing ArcGIS Online layers will allow you to map point locations of EPA regulated facilities. To use ArcGIS Online, you will need to create a user name and password for the site.
Google Earth is a widely used platform to study spatial data. It has particular appeal in its engaging graphics and interface. The EPA releases data in Google Earth format. To use this data, you will first need to download and install Google Earth
. Next, you will need to download the TRI dataset for Google Earth
(look for the national .kmz file). Once you have both you can open the TRI database in Google Earth.
Stand Alone GIS Software Packages
Though Web GIS features are becoming increasingly diverse, complex, and customizable, many analysts wishing to design their own maps, generate their own specific queries, and conduct analysis with a diversity of data layers prefer to use stand alone GIS software packages. Though all GIS software integrates the web to some degree, stand alone packages provide downloadable software that allows users the most flexibility in managing, creating, visualizing and analyzing their own data. A variety of commercial and open source options are available, and the choice of which package to select depends on the user’s resources, needs and experience. Some of the most common commercial packages include ESRI ArcGIS, MapInfo, and AutoCAD Map 3D. Open source packages, which are free, include Quantum GIS, Diva GIS, Map Window, and GRASS.
Commercial packages typically come with a large suite of analysis tools and customizable templates and platforms. ArcGIS
is commonly used in government and industry to produce publication quality maps, customized web maps, and to input, track, and analyze large volumes of spatial data. Commercial packages typically provide users with access to customer service and training programs on how to use the software.
Open source software packages have the distinct advantage of being free. They are also highly customizable, with open access to software design and code. Packages like Quantum GIS
work across platforms (not just on Windows, as is the case with ArcGIS). There are fewer analysis tools and display options, but making GIS software globally accessible is tremendous benefit.
The sections in this tutorial will guide you through the process of working with EPA spatial data in both ESRI ArcGIS and Quantum GIS.
Specialized Analysis Software
Last, there are very specific GIS tools for very specialized types of analysis that are also important. For example, if you would like data on how specific toxins travel through the air, ground, or water, you will need to probably need to gather your own data and create a custom project. Several EPA tools are designed to help with various tasks in this endeavor. One example of a specialized software for TRI data is the Risk-Screening Environmental Indicators (RSEI) program, which allows users to identify and compare health risks generated from TRI emissions. Because the data are tied to regulated facilities, it is spatial in nature, and functions as specialized GIS software. Other specialized GIS software allows you to examine correlations over space (GeoDa), and space and time (STARS). To review, for easy and quick access to data, web GIS tools will probably cover your basic needs. For more customization of the display, and control and analysis of the data, stand alone GIS packages, and some training in GIS will meet your needs. For very specific data and analysis tools, specialized software may exist, or you may need to customize your own tools for the job.
There are two data models that operate in a GIS: vector data (point, line, and polygon, e.g. cities, roads, and country boundaries) and raster data (often satellite imagery, but any data saved and arranged in a gridded format). Both data models are an essential part of GIS analysis.
Most states in the US maintain their own geospatial data warehouse. For New Jersey, see the New Jersey Geospatial Information Network.
Environmental Data – Relating to EPA’s Toxic Release Inventory
Downloads for TRI data are available in several locations, including from: the EPA TRI Website, Envirofacts, Data.gov, and TOXMAP.