GREELEY — An 11-well oil and gas industrial pad hummed as students played outside Bella Romero K-8 Academy this week, a month after tests by Colorado’s health department detected elevated levels of cancer-causing benzene in the air.

State officials have declined to shut down these Extraction Oil and Gas wells, saying they can’t pinpoint the source of the benzene. Air tests using a mobile state lab resumed Wednesday to try to verify the source.

“We want to make sure we are responsive to concerns in the community, to make sure we are protecting the air around that school,” said John Putnam, environmental programs chief at the Colorado Department of Public Health and Environment.

“The chemical signature suggests that it is from an oil and gas industry source,” he said. “The challenge for us is that there are a lot of oil and gas sources in that area.”

The state detected the elevated benzene over a 45-minute period. There’s no indication from current data of a pattern of elevated benzene pollution and school officials say they’ve been advised students are safe.

“What we want and need is for our students to be safe. We believe they are at this time,” said Theresa Myers, spokeswoman for Greeley-Evans School District 6. “We are taking our guidance from the Colorado health officials. They are telling us they believe it is absolutely safe for those kids to be in the school.

Over the past month, student health problems reported at the school remained normal for this time of year, officials said.

Extraction drilled the wells about 1,200 feet from the Greeley school, a project that has drawn national attention. Company officials said they’ve been collecting their own air samples since Nov. 22, the day after the state health department notified Extraction that tests on Nov. 5 measured benzene at 10.24 parts per billion outside the school as students were leaving. The federal health guideline is 9 parts per billion though industry experts say exposure at many times that guideline is safe.

“We have seen no exceedances during the period we’ve been testing,” Extraction spokesman Brian Cain said.

Benzene often is found in air pollution from burning fossil fuels. Inhaling it can cause drowsiness, dizziness, headaches and, at high levels, unconsciousness. Long-term exposure leads to blood problems including leukemia, according to a federal hazard assessment.

Extraction uses the best low-pollution technology and if gas leaks, sensors automatically shut down wells, Cain said, suggesting other oil and gas companies likely are to blame for the elevated benzene detected at Bella Romero.

Colorado officials have approved permits allowing more than 23,000 active oil and gas wells in Weld County, including 386 wells inside Greeley city limits.

But this school situation — happening as world leaders at a climate summit in Madrid grapple with lagging efforts to reduce heat-trapping greenhouse pollution from burning fossil fuels — reflects tension around shifting priorities in Colorado. State law now requires government agencies to prioritize the protection of public health and the environment. State air quality officials had deployed the mobile air-testing lab proactively at the school to make sure children are safe.

The latest state study on oil and gas industry health impacts found air emissions can hurt people at distances up to 2,000 feet from wells, depending on wind. Back in March 2017, when the Colorado Oil and Gas Conservation Commission issued Extraction a permit allowing the wells near Bella Romero, state law required only a balancing of interests aimed at maximizing the production of fossil fuels.

Colorado regulations at the time the permit was approved required a 1,000-foot buffer between school buildings and drilling operations. A rule change that went into effect earlier this year requires such “setbacks” be measured from the edges of school sports fields and playgrounds, not just buildings.

“Willful and wanton conduct”

Public concerns persist.

“A full 21 days passed before we were notified of the exposure,” Greeley parent Patricia Nelson wrote Tuesday in a letter to Gov. Jared Polis requesting intervention. “It would be negligent, in fact, willful and wanton conduct, for you to allow continued oil and gas operations at this site until you can be certain that no further benzene exposure will occur.”

Her son attends a separate Bella Romero school for grades 1 to 3 a half mile to the west, and next year may attend this academy for grades 4 to 8 where the edge of the playground sits less than 900 feet from Extraction’s wells.

State officials emphasized a commitment to monitoring air quality, especially where they receive complaints about oil and gas industrial pollution.

“We are trying to figure out, as best we can, where it might come from. … We’re trying to do as much as we can. … It is hard to know exactly what happened out there,” said Putnam, of the state health department. “If you were to request that something be shut down, you’d need to make sure you knew it was the source of the emissions.”

Extraction’s air-testing equipment can measure benzene at levels as low as 0.5 parts per billion. The average benzene concentration measured in the air near the school since Nov. 22 has hovered around that level, “with no results above 1 part per billion,” Extraction’s Cain said.

Company officials vowed to do all they can to find the source of the benzene and ensure student safety.

When state air quality officials notified Extraction of the elevated benzene, “we immediately deployed our air monitoring teams” and “we have shared, and will continue to share, this data with the CDPHE and COGCC to the extent it is helpful to their efforts,” Cain said.

“And we are coordinating a longer-term air monitoring plan to ensure that the air quality in this area is well understood. Since deploying our monitoring efforts throughout the area, the ongoing and continuous air monitoring and sampling do not indicate any levels of concern.”

Editors note: This story has been updated to provide additional context regarding the levels of benzene.