“Benzene and 2-ethyltoluene were of primary concern, showing acute HQs above 10 at the selected receptors 500-ft downwind during development activities,” wrote the study’s authors, air-quality scientists with the consulting firm ICF International. “Maximum HQs were between 1 and 10 at the selected 2,000-ft receptor for benzene at all three sites (HQ=1.8–5.3; during all activities except for flowback at the Garfield County valley site and fracking at the NFR site, where HQs were below 1).”
In an article summarizing their findings in the peer-reviewed Journal of the Air & Waste Management Association, researchers distilled their conclusions into slightly more readable language: “Acute exposures were of greatest concern, primarily during O&G development and for a limited set of VOCs and critical-effect groups, sometimes at distances out to 2,000 feet from the well pad.”
Or, simplest of all, in the words of Colorado health officials: “The study found that there is a possibility of negative health impacts at distances from 300 feet out to 2,000 feet.”
The CDPHE’s long-awaited study, funded by the state at the recommendation of an oil and gas task force convened by former Governor John Hickenlooper in 2014, is based on air samples collected near Colorado fracking sites with the cooperation of drilling companies between 2013 and 2016. It uses statistical modeling to assess the risks of exposure to airborne pollutants for people in close proximity to drilling sites — a methodology that oil and gas groups, reacting to the study’s release on Thursday, rushed to criticize.
“Using modeled exposures instead of measured air quality data introduces uncertainties and limitations that may result in erroneous estimates of risk for a population,” Lynn Granger, executive director of the Colorado Petroleum Council, said in a statement.
Such modeling methods, however, are a common tool used by air quality researchers to estimate the real-world impacts of measured emissions. Collecting and analyzing ambient air samples is expensive and time-consuming, and recording enough individual measurements to fully account for all variables — time, distance, weather conditions, topography, human activity and more — isn’t feasible.
The study released Tuesday analyzed more than 5,000 air samples collected by researchers from Colorado State University in a pair of emissions studies completed in 2016. At the time, researchers and state health officials hailed the CSU data as one of the comprehensive sets of oil and gas emissions measurements ever recorded. Using modeling tools developed by the Environmental Protection Agency, the CDPHE’s new study extrapolated the measured data into millions of potential exposure scenarios — “many more than can be reasonably observed with monitoring,” its authors note.
The result is one of the most robust assessments of the health effects of oil and gas drilling yet completed — and specifically, one that raises the possibility that current "setback” distances mandated by the state aren’t enough to protect many Coloradans from short-term health risks.
But while the study is a major development — it’s been the object of a lot of anticipation and speculation since it was first announced three years ago — it’s far from the first attempt to settle the question of whether fracking threatens public health and the environment.
These latest findings are best understood in the full context of what we knew long before Thursday’s announcement. Here are three of the most important things to recognize about the impacts of fracking in Colorado and beyond.
1. Modern drilling technologies have led to much greater impacts.