Denver’s ozone pollution prompts environmental policy concerns


High summertime levels of ozone in Denver metro and the North Front Range may soon trigger higher costs for gasoline and other products and more restrictions on emissions of ozone-creating precursor compounds from industries, according to a new draft report from the metropolitan's air quality planning agency.

A hike in gasoline prices to pay for a more expensive formulation that is not as prone to emitting precursor compounds is also likely as early as 2024 if Colorado cannot meet EPA ozone standards, which would result in the region’s ozone pollution classification as “severe.” High levels of ozone can cause respiratory health problems in children, older adults and those with respiratory diseases.

David Sabados, communications director for the Regional Air Quality Council (RAQC), told The Denver Gazette he’s uncertain how much more a reformulated gasoline – or RFG – might cost.

“There’s a lot of factors that go into gas pricing and, to the best of our knowledge, the fuel industry has never given a hard number on cost increases for RFG,” Sabados said. “I don’t have a hard citation, but 20-30 cents per gallon increase is likely given what we’ve seen in some other areas as we’ve tried to find numbers ourselves.”

This uncertainty comes at a time when Colorado citizens are facing an economic downturn, rampant inflation and increased costs for almost everything, especially gasoline.

“Once we go severe, by EPA rule, reformulated gasoline has to go in place one year later, at the beginning of the next summer season of gasoline, which typically begins in May of a year, so likely we would see reformulated gasoline in the summertime of 2024 and beyond,“ said Mike Silverstein, RAQC’s executive director during an online press briefing Tuesday.

California has been the bell-weather for reformulated gasoline since 1992, when the California Air Resources Board required modifications to gasoline formulas to reduce vapor emissions, remove lead and otherwise make gasoline less harmful to the atmosphere. CARB has tinkered with formulations and procedures to reduce emissions ever since. One required improvement is the use of vapor-capture equipment on gasoline pumps that recover fuel vapors at the nozzle.

Citing a 2003 report, CARB says the benefits of the program "have been equivalent to the removal of 3.5 million vehicles from California's roads.”

Curbing emissions that create ozone could also mean changing habits, such as how residents drive, what people buy at the store and even how homes are heated.

“We're going to have tougher consumer products requirements," said Silverstein. "Over time we already have tough consumer products requirements, but they have to go to the next level as a contingency measure.” 

Ozone problems the region faces include its topography, weather patterns and the fact, says the report, that more than 50% of the volatile organic compounds that can contribute to the creation of ozone come from natural, uncontrollable “biogenic” sources, such as methane produced by decomposition in wetlands and lakes.

“It's part of the ozone situation,” Silverstein said. “Other areas have the same, or even higher biogenic emissions, but they're complying with the standard because they have either better meteorology (weather), or they don't trap air pollutants in the region due to terrain or the unique features we have in our front range. But you don't get a pass from the EPA.”

High temperatures, intense sunlight and persistent high-pressure systems that keep winds down in summer cause precursors – volatile organic compounds (VOC) like methane and industrial solvents, and nitrous oxides (NOx) produced by motor vehicles and other combustion sources, including power plants – to linger in the region and be turned to ozone.

The report from the RAQC said emissions from industrial facilities, electric utilities, exhaust from motor vehicle and off-road equipment, gasoline vapors, chemical solvents and even household chemicals are some of the major sources of NOx and VOC.

State and local officials have long struggled with meeting increasingly tougher EPA ozone standards, which were tightened several times between 1978 and 2008.

In 2018, the EPA reclassified the region from “moderate” to the “severe” nonattainment category, which triggered revisions to the state implementation plan (SIP), which informs EPA how Colorado plans to meet the ozone standards by 2027.

The region – comprising eight counties including Jefferson, Boulder, Larimer, Denver, Jefferson, Douglas, Arapahoe, Adams and Weld – have had seasonal problems with ozone levels for decades. It was declared a “nonattainment” region in 1978, when ozone levels exceeded 120 parts per billion, the 1978 EPA national ambient air quality standard.

In 2020, EPA downgraded the region to “moderate nonattainment,” which triggered yet another SIP that would go into effect in 2024 if the state cannot get a handle on ozone pollution, which the report says is unlikely.

Ground–level ozone is not emitted directly into the air. Rather, it is created by complex chemical reactions between nitrogen oxides (NOx) and volatile organic compounds (VOC), and, to a lesser extent, carbon monoxide (CO), in the presence of sunlight, the report said.

According to Silverstein, the EPA doesn’t care where the precursors come from, even if they, or ozone itself, blows in from other states or even other countries, and that what’s important to the agency is meeting ambient air quality standards.

“We essentially assume that we have control of about 25 to 30% of the ozone in our region,” Silverstein said. “And that's what we're responsible for developing strategies to control.”

But Silverstein says we don't get a waiver for natural emissions, except under extraordinary circumstances like ozone from wildfires or that occasionally gets blown down into the Denver basin from the stratosphere, in which case, if the state can prove it, EPA will overlook the violation.

Comments on the draft report may be submitted in writing to RAQC through July 27th. People who would like to share comments in person can sign up for the August 5th Zoom board meeting by emailing Misty Howell

Further information can be found at the RAQC website.

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