Project methodology
Reporters from the Houston Chronicle and researchers from the Mary Kay O’Connor Process Safety Center at Texas A&M created a first-of-its-kind study showing the potential harm to the public posed by hazardous materials at local businesses.
The Chronicle, in 2015, obtained the chemical inventories, called Tier Twos, for about 2,500 businesses. Companies are required by federal law to submit their Tier Twos annually to the state, first-responders and Local Emergency Planning Committees.
A&M researchers started by looking at the materials themselves.
Chemicals can be harmful in three key ways: flammability, reactivity and toxicity.
Flammability represents the harm posed by fires or explosions. The National Fire Protection Association (NFPA) rates a large number of chemicals based on their flammability. These ratings were used when possible. If an NFPA rating was not available, the flammability rating from the chemical’s Material Safety Data Sheet was used instead.
Reactivity represents the instability of a substance in certain conditions. The NFPA also rates chemicals on their reactivity. These ratings were used when possible, and if not, drawn from the chemical’s Material Safety Data Sheet.
Toxicity represents the harm posed to human health or the environment. The NFPA rates chemicals on toxicity, but does not distinguish between types of exposure. Since inhalation hazards are the most dominant threat, the NFPA ratings were modified by A&M according to the chemical’s lethal Protective Action Criteria number, created by the U.S. Department of Energy. These values are based on a chemical’s maximum airborne concentrations before life-threatening effects occur.
The potential for harm from toxicity, reactivity and flammability were weighted equally.
So a chemical with a score of 4 in any single category was rated more dangerous than a chemical with 3s in each category.
Since each facility can have multiple chemicals, the final rating was based on the chemical with the highest potential for harm.
The amount of chemical stored at a facility also factors into the harm a business could pose to the public. A highly toxic chemical would be potentially less harmful to the public if only small amounts were at the facility.
Researchers created a penalty multiplier based on the quantity
of the chemical.
The number of people living near a facility increases or decreases the harm a business could pose to the public.
Researchers created a penalty multiplier based on the population within a 2-mile radius of a facility. This information was pulled from the EPA and U.S. Geological Survey’s LandView database.
Overall scores ranged from 2, with the lowest potential for harm, up to 14.
The ratings were divided into three groups – low (2 to 6 on the scale), medium (6 to 10) and high (10 to 14).
A&M researchers consider a facility’s accident history relevant to its potential for harm but that was not included because comprehensive accident histories don’t exist.
But A&M researchers endorsed the use of regulatory histories. So the Chronicle acquired the OSHA inspection history for every facility with a rating of 9 or higher. Many facilities had not been inspected within the last five years. A&M recommended that facilities with OSHA process safety violations receive a one-point penalty. Six facilities – Syntech, WymanGordon, Goodyear, Lubrizol Deer Park, Bayer Material Science and the Arkema plant on Haden Road – moved from the mid-tier to the highest category due to their inspection histories.
Each facility scoring a 10 or higher was sent a letter detailing the analysis, an explanation of its score and an offer to respond to the evaluation. Four companies sent the Chronicle updated information on chemicals in their inventories. A&M recalculated scores, and those companies moved down to the mid-tier.
The Chronicle received AkzoNobel Surface Chemistry’s Tier Two in 2016. A&M evaluated its inventory using the study methodology, and the plant landed on the high potential for harm list.