A surprising new discovery suggests that the oil and gas industry, which has been booming in recent years in parts of North America, can produce ground-level ozone pollution in wintertime under certain conditions.
The new NOAA-led research, published in Nature this week, explains how chemicals released into the air in fossil fuel production can form enough ozone in winter to surpass federal health standards.
Increased levels of ozone can cause respiratory problems in the elderly, and those with asthma and other breathing conditions.
The finding, which centred on oil and gas development in northern Utah’s Uintah Basin, initially puzzled scientists. Normally, ozone pollution is seen in summer in urban centres when more intense ultraviolet radiation in the form of sunlight can induce the necessary chemical reactions. Ozone is a naturally-occurring inorganic gas that appears in low concentrations in the Earth’s atmosphere.
While man-made urban air pollution is the major source of ozone haze in cities, it’s declining in severity in North America but on the increase in developing economies, particularly in East Asia.
However, the mountain basin in northeastern Utah offers the perfect mix in environment and chemicals to produce large amounts of ozone in winter.
“The recipe for ozone appears to be emissions of what are called volatile organic compounds (VOC) and Nitrous Oxides (NOx), combined with a very stable meteorology that traps these pollutants together that will lead to larger buildup of ozone over time,” explained co-author Steven Brown, a scientist with NOAA in Boulder, Colorado.
“A key aspect of the analysis in our paper was to understand the sources of oxidants, because these oxidants are normally at their minimum in the winter season.”
And it appears that a ‘perfect storm’ occurs for ozone pollution in northeast Utah in that NOx and VOC are present in the correct ratio for the ozone production in winter conditions. Brown and his team specifically show that the VOC levels in Utah are large enough to really optimize the production of ozone. Even the snow on the ground adds to the problem by accelerating ozone production, since it is so highly reflective of sunlight.
The air is trapped within the basin for long periods, from days to weeks at a time, during which ozone production occurs, Brown says.
“It is the combination of stable, winter mountain basin meteorology and emissions of ozone precursors from the oil and gas activities that leads to large ozone production,” Brown said.
The Environmental Protection Agency measurements show that 97% of the VOCs present in northeastern Utah originate directly from the local fossil fuel industry. And in the 2013 winter season alone, ozone levels shot above the normal air quality standards 49 times.
To put that into perspective, the authors point to the densely-populated city of Riverside, California where air quality standards were exceeded half that amount – and only in summer.
“Thus, northeast Utah is clearly vulnerable to this kind of pollution, as would any mountain basin with winter meteorology and the right mix of emission sources,” Brown added.
While the Utah study does not address Canadian oil and gas production specifically, Brown does point out that if oil and gas production in Canada occurs in basins with stable meteorology, then those may in fact be susceptible to the same phenomenon. However, no such events have yet been observed to his knowledge.
Brown does point out that they still aren’t sure how widespread this type of pollution is in terms of fossil fuel production, since it has never been observed before. But it is something that both scientists and engineers within the industry are taking seriously.
"The oil and gas industry has worked co-operatively with us to undertake these field studies and to determine the best mitigation strategies, so we expect that co-operation to be ongoing,” Brown said.
“Our goal is not to alarm the public, but rather to make the public aware of this phenomenon and to provide analyses that will be useful to policy makers and other stakeholders in developing ozone pollution mitigation strategies.”
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