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Haze behind Denver's City and County Building on the afternoon of Thursday, Oct. 31, 2019. (Jesse Paul, The Colorado Sun)

Colorado’s air quality regulators on Friday adopted a new plan to combat Front Range ozone pollution that will tighten emissions from oil wells, boilers and automobiles, and may even change the way paint dries.

The new plan is necessary as the federal Environmental Protection Agency is set next year to drop the region’s ozone status to “severe” from “serious.” The lack of an approved plan could jeopardize $434 million in federal transportation funds for Colorado.

Ozone is a corrosive gas created when nitrogen dioxide (NOx) and volatile organic compounds (VOCs) cook in heat and sunlight. 

The compound has been linked to respiratory and heart problems, and the EPA has been lowering the acceptable health level as more research emerges on ozone’s health effects.

Ten Denver metro area and northern Front Range counties have been out of compliance with the 2008 federal benchmark — 75 parts per billion — since 2012. A 2015 update lowered the standard to 70 parts per billion, but for now the region is attempting to align with the 2008 standard.

The new State Implementation Plan, or “SIP,” was unanimously approved by the Colorado Air Quality Control Commission after three days of hearings. Gov. Jared Polis issued a statement to the commission Tuesday in advance of the hearings, noting that he will not seek a waiver from the downgrade.

One part of the plan targets VOC leaks from equipment at oil and gas production sites, as the industry is a major source of air pollution. For example, if an oil or gas well within 1,000 feet of neighborhoods and occupied areas is leaking, its operators have to seal the leak within five business days. 

“Our industry worked closely with partners in the environmental community and local governments in advance of this most recent air rulemaking to reach an agreement that ensures equipment will be repaired quickly at well pads close to communities,” the Colorado Oil and Gas Association, a trade group, said in a statement Friday.

The largest source of NOx is transportation, and the new SIP has to address the growing volume of traffic in the region. Other sources of NOx include boilers and turbines, such as those used by plants that generate electricity, which would need to have reasonable control technology.

The new rules will apply to sources emitting more than 50 tons a year of VOCs or NOx.

Other sources of VOCs are wood surface coatings, foam manufacturing and “architectural coatings” — better known as paint. (VOCs, added to paint to help color adhere and the coating to set up quickly, are emitted as paint dries. The EPA limits the amount of these chemical solvents that may be present in when paint is manufactured, but some governments in non-attainment areas have restricted them further to help reach ozone-reduction goals.)

The Front Range SIP also seeks a 90% reduction in VOC emission in foam manufacturing.

State and local governments will also have to take the SIP into account in their transportation and land-use planning.

The SIP includes computer models that simulated emissions and meteorological conditions to assess the trend in ozone levels and the potential effect of various control strategies. The model’s results became a point of contention during the hearings as some community representatives argued that real-time, on-the-ground measurements were more accurate.

The commission acknowledged the models’ shortcomings in a preface to the finalized plan and will likely pursue further investigation to get more accurate models as it implements the SIP’s changes.

MORE: Front Range air quality is terrible, but Colorado’s efforts are showing some improvement in ozone pollution

Advocacy groups from around the state largely praised the updated plan, though Jacob Smith, executive director of Colorado Communities for Climate Action, noted that the commission could have been more aggressive in reducing ozone emissions.

“This is an important step forward, but we’ve got a long ways to go and it would have been better to take a bigger step,” Smith said.

The Denver metro area’s ozone problem is not unique, though it’s not clear how many metro areas nationwide are out of compliance with federal standards. And it’s one thing to say that a region needs to reduce emissions, but Smith says that local governments often don’t have enough power to make that happen on their own without state or federal intervention.

“It’s not an easy problem to solve,” Smith said. “We know what the answers are, but they can be difficult to do and they often run into political resistance.”

Mark Jaffe contributed to this report.

Lucy Haggard

Lucy Haggard was a TRENDS Reporting Fellow from August 2020 to May 2021 with The Colorado Sun. Email: Twitter: