The Oil & Gas Threat Map utilizes several types of data to display and calculate potential impacts: oil and gas facility data, air toxics health risk data, Census demographic data, and school and medical facility location data.
Facilities listed in the map are limited to 1.2 million active production wells, natural gas compressor stations and processing plants (e.g. not refineries or storage wells) because they are the most likely to be governed by federal and state standards to eliminate methane pollution by the oil and gas industry.
Oil and Gas Facility Data
Oil and gas well data was downloaded directly from state government agencies by the Fractracker Alliance.The data includes active conventional and unconventional wells, and is from 2014 & 2015.
Gas compressors and processor data were primarily taken from a variety of state and federal databases:
- Nationwide location data for gas processors was compiled by the Clean Air Task Force using the Environmental Protection Agency’s Greenhouse Gas Reporting Program and Energy Information Administration, as well as the Oil and Gas Journal.
- Location data for compressors stations and additional processors in Alaska, Colorado, Louisiana, New Mexico, Pennsylvania, Texas and Wyoming was compiled by Marchese et al., and provided by the Environmental Defense Fund.
- Compressor station locations in California and Ohio were extracted from the Environmental Protection Agency’s National Emissions Inventory by the Clean Air Task Force.
The well data included in the Oil & Gas Threat Map is comprehensive. The data for compressor and processors is not. State and federal agencies do not monitor compressors and processors as closely as they do wells, and data is less available to the public. Because compressors and processors are often co-located with wells, it is likely that most “missing” facilities are still encompassed within the Threat Radius. Facility data gaps also partially explain why the air toxics health risk data show elevated risk from oil and gas air pollution in some counties where facilities are not shown on the map.
Air Toxics Health Risk Data
Recent analysis by Clean Air Task Force (featured in the report Fossil Fumes) estimates cancer risk and respiratory health risk to residents of every county in the United States that can be traced back to air toxics from the oil and gas industry. It is based on EPA’s most recent National Air Toxics Assessment (NATA) analysis updated to reflect EPA’s projection of 2017 emissions from EPA’s National Emissions Inventory.
The purpose of NATA is to identify and prioritize –
- air toxics,
- emission source types, and
- locations that are of greatest potential concern when looking at overall health risk in populations.
NATA calculates risk estimates for two types of health impacts that can result from toxic air emissions:
- cancer risk and
- respiratory health risk.
The metric for cancer risk is the number of cancer cases per million people exposed; areas with cancer risk above 1-in-a-million are considered to be above EPA’s level of concern.
For respiratory health risk, the metric is the hazard index; areas with a respiratory hazard index above 1 are above EPA’s level of concern for potential harm to the respiratory system, including breathing problems, harm to the lungs, or other respiratory diseases.
Population statistics were calculated by FracTracker using data from the 2010 US Census at the Census block level, which is the finest grained resolution of data available.
Census data does not include street address information. So the population within the Threat Radius was estimated by
- Determining the ratio of each census block that was within a half-mile of the nearest oil and gas facility compared to the total area of the block;
- The resulting quotient was then applied to the various demographic totals within the block, rounded to the nearest integer, to determine the estimated threatened population for the block;
- This result was then aggregated at the county and state levels.
School and Hospital Data
Hospital location data was sourced from the Geographic Names Information System (GNIS) part of the U.S. Geological Survey.