Processing the Emissions data for MapEcos was a major undertaking. We tried to be as unbiased and informative as possible within the constraints set by the size of the location point bubbles.  We tried also to be careful and accurate, but we are certain that some errors remain.  This page provides more detailed information about how we processed these reported data.

Emissions

We chose to report data on chemicals that were released into the environmental at the facility (i.e. onsite emissions).  Facilities often process waste material before releasing it or transfer it offsite for processing by others.  We report data on the chemicals that were directly released to the environment by the facility (often the residual after such processing).  We do not include chemicals that were transferred and released into the environment at other locations.

Emissions data were calculated from the 2007 release (2005 reporting year) of the EPA's Toxic Release Inventory.  For facilities that filled out a "Form A" short form of the TRI, we estimated the unreported emissions volumes as the mean value of emissions for that chemical, in that industry, and that year, among all facilities filling out a full "Form R" but which had emissions less than the threshold for that particular chemical.

Hazard

Hazard score in the "summary" tab are calculated as:

Note, we recentered the RSEI scores so that the average chemical in the TRI has a toxicity of 1.  Thus, if a firm has a lower hazard score than its lbs emitted, it is emitting less toxic chemicals.

Dot color and level

Most facilities in the US have emit only a few lbs of toxic chemicals, while a few facilities emit millions of lbs.  In calculating our levels and in setting the color of the facility marker dot, we wanted to take this into account.  As a result, we created an exponential level.  In our level scheme, the bottom 50% of the firms are in level 0, the next 25% in level 1, and so on.  Despite the reducing number of firms in each level, the total emissions from all the facilities in each level actually increase with the level (e.g. emissions from all facilities in level 9 > emissions from facilities in level 8).

Corporate Ownership Information

Firms report the identity of their corporate ownership to the TRI by reporting a name and a Dun and Bradstreet Identifier.  Unfortunately, the name of the facility is often inconsistently reported and the ID is invalid or does not match the name of the reported corporate owner.  To identify the corporate owner of each facility, we used a computerized matching program to match each facility to the National Establishment Time-Series (Nets) Database database. 

We report our estimates for the most recently released TRI year – 2005.

Location

We obtained location data from the Council on Environment Cooperation, the EPA, and automated requests to Google to geocode street addresses.  We attempted to identify the most accurate location information by comparing data from multiple sources, but location errors undoubtedly persist.  If you would like to report such an error, please click on the "report inaccurate information" link.

Line graphs

To create the line graphs, we first estimated the average for that industry (based on 2 digit Standard Industry Classification (SIC) codes.  We then logged this value to make graphing easier.  The graphs then report this logged "average" facility relative to the focal facility.

Histograms

To calculate the histogram graphs, we first calculated the log value of emissions for the facility in the comparison group (state, county, industry) with the most emissions.  We divide this number into 6 groups and calculate the number of firms in each group.