Small Group Of 'Super Polluters' Responsible For Majority Of Toxic Pollution

A "handful" of industrial facilities are responsible for the majority of toxic pollution in the past 15 years.

With collaborators, Dr. Mary Collins, assistant professor in ESF's Department of Environmental Studies and the Environmental Health Program, is the co-lead author of a paper that shows a small percentage of industrial facilities emit the majority of toxic pollution year after year. The paper was published in the journal, Environmental Research Letters

This study is the first is to identify the disproportionate nature of pollution production across a very broad range of industries. These findings have both scholarly and policy implications for how pollution is generated and how decisions might be made to reduce that footprint.

"We included more than 300 industries over a 15-year extended study time period. Our main purpose was to learn more about the stability of disproportionate patterns of pollution production."

The study by Collins and Simone Pulver of UC Santa Barbara examined data from the U.S. Environmental Protection Agency (EPA) from 1998 to 2012 from 25,000 facilities in 322 industries.

Within that data set, Collins said they "could identify a few facilities that generate more than 50 percent or more of total annual hazardous emissions within their industry," Collins said.

These "super polluters" are industrial facilities that produce unusually high levels of pollution each year. "There aren't that many of them, but together they account for the majority of annual industrial pollution," said Collins.

"A small group generates much more harm than the rest of the group and this pattern is consistent over time and across many industries," she said and were not contained within similar industries or the goods they produced.

The study has "significant implications" for how decision-makers regulate pollution. Decreasing toxic emissions might be achieved by focusing on a relatively small number of facilities, rather than industries as a whole.

"We would suggest that targeted strategies to impact those who are causing the problem would go a long way towards decreasing total emissions," Collins said.

"If you were a decision-maker charged with regulating or cleaning up a specific industry, you might try to target these worst actors, engaging in a targeted decision-making strategy," Collins said.

But there's also a flip-side to the problem. With a decision-making strategy that's based on regulating the super polluters, emissions caps set might be too high for the average polluter. For example, "if you set a cap based on the super-polluter average, it would vastly overestimate most of the actors and vastly underestimate the few that are causing the problem, over-regulating most and under regulating the worst of the worst," she said.

Researchers also found it's not always the same group of facilities each year producing excessive amounts of pollution. "Out of 25,000 facilities, there were only 31 facilities that were consistently in the extreme polluter category within their industry throughout the study period," said Collins.

Researchers now need to know why these facilities exist and persist over time. "Understanding more about why one facility generates so much harm one year and not the next year and why are some facilities stable, are the questions that emerged from our project that we haven't answered yet," said Collins.

This idea was first introduced in 2005 by Bill Freudenburg of UC Santa Barbara who was Collins's dissertation advisor. Collins noted the study was a faculty-student collaboration. ESF graduate student Dustin Hill is the third author on the paper and UC Santa Barbara student Ben Manski is listed as the fourth author.