18 Sep By Michael Howard: Understanding Environmental Impacts: What Air Quality and Noise Studies Tell Us about Oil and Gas Setbacks

The Colorado Energy and Carbon Management Commission (“ECMC”) publicly released and reviewed three recent state specific studies related to public health risks associated with living near oil and gas development in Colorado and requested public comment. This Blog post reviews one of these studies, authored by Jeffrey L. Collett Jr. and colleagues, titled “Measuring and Modeling Air Pollution and Noise Exposure Near Unconventional Oil and Gas Development” (“The Study”).

Over the past 20 years, the majority of recent growth in oil and gas production has occurred through unconventional oil and gas development (“UOGD”), being the combination of horizontal drilling with hydraulic fracturing.  This includes Colorado’s Denver Julesburg basin, also known as the “DJ Basin.” Since the introduction of UOGD in the DJ Basin, the DJ Basin has seen significant growth in energy production, while simultaneously, communities along the front range have seen immense growth. In response to these growing conflicts between residents and energy development, Colorado enacted State Senate Bill 181 (“SB 181”) which changed how the state regulated oil and gas development. One of the major policy changes was increasing oil and gas operation setbacks. Setbacks are the mandated minimum distances required between energy development and infrastructure and/or sensitive areas like homes, schools, and hospitals. Prior to 2013, Colorado had minimum setback of 350 feet. Effective August 1, 2013, the minimum setback was increased to 500 feet around a building unit and 1,000 feet around High Occupancy Buildings, Schools and Child Care Centers. After SB 181, in 2021, the ECMC increased these setbacks to a presumptive 2,000 feet around Residential Buildings or High Occupancy Buildings less certain exceptions. The Study used these setbacks to analyze air quality and noise impacts from oil and gas operations at four well pads in the DJ basin from October 2022 to August 2024.

Air Pollution

The Study did not identify any chronic health hazards at these four well pads and found that no chronic exposures exceeded health guideline values. Although hazardous air pollution concentrations varied considerably, the highest concentrations were seen in intermittent plumes and the researchers concluded that the primary concern was the potential for short term, not long term exposure. Their modeling showed that by the time those plumes reached the 2,000 feet setback, concentrations were below applicable health guideline values. Therefore, the researchers concluded that Colorado’s “2,000 foot setback requirement is protective for all investigated unconventional oil and gas development operations.”  The Study further found that implantation of closed-loop, tankless fluid-handling systems can reduce flowback emissions of benzene by more than 98% relative to other completion operations. 

Noise Pollution

The Study also reviewed noise pollution. The Study measured both A-weighted (dBA) and C-weighted (dBC) noise because they measure different aspects of sound. A-weighted noise reflects how loud a sound appears to the human ear and is the standard metric used in most noise regulations. C-weighted noise captures much more of the low-frequency rumble produced by equipment such as drilling rigs, compressors, and hydraulic fracturing pumps. By measuring both, the researchers were able to assess not only how loud nearby residents would perceive the operations, but also their exposure to low-frequency sound that can travel farther and may not be fully reflected in traditional dBA measurements. The Study found that both A and C weighted noise exceeded Colorado’s chronic noise thresholds at 350 feet during monitored operations. However, at 1,975 feet, The Study found A-weighted noises did not exceed ECMC chronic thresholds during drilling and coiled tubing/millout activities and only occasionally exceeded the threshold during hydraulic fracturing. However, C-weighted noise frequently exceeded the thresholds during drilling and hydraulic fracturing and only sporadically exceeded the thresholds during coiled tubing/millout operations.

Why Does This Study Matter?

The ECMC publicly released the study, hosted a community webinar explaining the findings, and accepted public comments before considering its implications. That public process reflects the importance of understanding how modern oil and gas operations affect nearby communities.

As residential development continues to expand near UOGD, questions remain about whether Colorado’s existing setbacks and operational requirements adequately protect public health. This study provides important scientific evidence to inform that discussion.

First, researchers found that for the four Colorado well pads evaluated, the state’s 2,000-foot setback was protective against the acute noncancer hazardous air pollutant risks they assessed. The Study also documented significant improvements in emissions resulting from modern operational practices. In particular, operators’ use of closed-loop, tankless fluid-handling systems can reduce flowback emissions of benzene by more than 98% compared to traditional completion methods. Due to the significant reduction in benzene emissions, operators should proactively review their completion operations and determine if moving to a closed-loop tankless system is viable when conducting operations in the DJ basin.

Furthermore, the analysis of A-weighted noise, how loud a sound is, found that operations generally complied with the ECMC chronic threshold for a 2,000 foot setback, although hydraulic fracturing occasionally exceed those limits. The Study’s Air Quality and Noise Impacts results are particularly relevant because many advocacy groups continue to seek setback distances of 2,500 feet or greater. While the authors appropriately caution that their conclusions apply to the Colorado operations they studied, the results provide evidence that Colorado’s presumptive 2,000-foot setback provides substantial protection for residents living near new well pads that employ these modern practices.

You can read the summary regarding the other two studies as well as the full study here:

J.L. Collett, Jr et al., Measuring and Modeling Air Pollution and Noise Exposure Near Unconventional Oil and Gas Development in Colorado, Health Effects Inst., Resp. Rep. No. 232, at 1 (Dec. 2025), https://pubmed.ncbi.nlm.nih.gov/41913658/.

By Michael Howard, Senior Attorney at KMD Law