Chemicals released into the air by oil and gas exploration, extraction and related activities can spark reactions that lead to high levels of ozone in wintertime, high enough to exceed federal health standards, according to new NOAA-led research, published today in Nature.

The study comes at a time when new technologies are helping to accelerate oil and gas development in Utah’s Uintah Basin, elsewhere in the United States and in many other countries, and its findings may help air quality managers determine how to best minimize the impact of ozone pollution. When ozone levels spike, Environmental Protection Agency experts recommend that people, especially those in sensitive groups—children, the elderly, and anyone with pre-existing respiratory conditions—limit time outdoors.

Winter ozone pollution is surprising because normally, the more intense sunlight of the summer season can spark the chemical reaction that creates ozone pollution, said lead author Peter Edwards, a scientist with NOAA’s Cooperative Institute for Research in Environmental Sciences (CIRES) at the University of Colorado Boulder at the time of the study, and now with University of York in England.

However, Edwards and his colleagues showed that in winter in northeastern Utah, levels of volatile organic compounds (VOCs) build high enough that they can trigger pollution-forming reactions, themselves.

“This is not the usual spark for ozone formation, but it’s a potent one,” Edwards said. “Under certain wintertime conditions, it can cause extreme levels of ozone pollution.”

In winter, warm air aloft can trap cold air below, creating an "inversion" that traps and concentrates air pollutants. The presence of snow increases light reflection and accelerates ozone production.

For instance, in 2013, ozone in Ouray, Utah, exceeded the national air quality standards 49 times. By contrast, in the densely populated, urban area of Riverside, California, the standards were exceeded about half as often that same year, but during the summer.

“So it’s the same starting ingredients, nitrogen oxides and VOCs, that form ozone in Riverside, but it’s a different spark in Utah in winter,” said coauthor Steven Brown, a scientist with NOAA’s Earth System Research Laboratories (ESRL) in Boulder, Colorado. “Under wintertime conditions, the much higher VOCs in Utah break down to make carbonyl compounds, which set off the ozone production.”

The research is based on data collected during a series of wintertime studies in Uintah Basin, led by scientist James Roberts, also with NOAA ESRL. “We encountered a range of conditions during the three winters, from snowy in 2013 and 2014, to virtually no snow in 2012,” Roberts said. “Oil and gas emissions of VOCs were high in all three years, but high ozone occurred only in the cold, snowy, stagnant periods.”

Researchers from NOAA, CIRES, and other institutions made detailed measurements of ozone and the chemical ingredients, such as VOCs and nitrogen oxides, that “cook up” into the pollutant, and they used chemical models to better understand the system.

“These studies in Utah have caused us to think about air pollution chemistry a little differently,” said coauthor Joost de Gouw, a researcher with CIRES working at NOAA ESRL. “Our findings could help state and local air quality managers who are faced with ozone episodes to design policies, and industry representatives to meet air quality standards in the regions where they operate.”

CIRES is a partnership of NOAA and CU Boulder.

Authors of “High winter ozone pollution from carbonyl photolysis in an oil and gas basin” are: Peter M. Edwards (CIRES and NOAA), Steven S. Brown (NOAA), James M. Roberts (NOAA), Ravan Ahmadov (CIRES and NOAA), Robert M. Banta (NOAA), Joost A. deGouw (CIRES and NOAA), William P. Dube´ (CIRES and NOAA), Robert A. Field (University of Wyoming), James H. Flynn (University of Houston), Jessica B. Gilman (CIRES and NOAA), Martin Graus (CIRES and NOAA), Detlev Helmig (University of Colorado), Abigail Koss (CIRES and NOAA), Andrew O. Langford (NOAA), Barry L. Lefer (University of Houston), Brian M. Lerner (CIRES and NOAA), Rui Li (CIRES and NOAA), Shao-Meng Li (Environment Canada), Stuart A. McKeen (CIRES and NOAA), Shane M. Murphy (University of Wyoming), David D. Parrish (NOAA), Christoph J. Senff (CIRES and NOAA), Jeffrey Soltis (University of Wyoming), Jochen Stutz (University of California, Los Angeles), Colm Sweeney (CIRES and NOAA), Chelsea R. Thompson (University of Colorado), Michael K. Trainer (NOAA), Catalina Tsai (University of California, Los Angeles), Patrick R. Veres (CIRES and NOAA), Rebecca A. Washenfelder (CIRES and NOAA), Carsten Warneke (CIRES and NOAA), Robert J. Wild (CIRES and NOAA), Cora J. Young (CIRES and NOAA), Bin Yuan (CIRES and NOAA), and Robert Zamora (NOAA).

Graphics: 
High-resolution images are available for download on CIRES’ Flickr account, News release album:

• Towering measurements NOAA and CIRES scientists installed instruments on a tower....
• Drilling rig in Uintah Basin, Utah.
• Sunset over a field in Uintah Basin where natural gas and oil development has increased.
• more