Environmentalists are asking regulators to consider slowing the pace of gas drilling in western Wyoming after several days of severe ozone pollution last winter.
Ozone levels in the Upper Green River Basin topped the highest levels in Los Angeles all last year. The ozone results from air pollution from gas drilling, which has picked up with the reviving economy.
The Wyoming Outdoor Council, Upper Green River Alliance and other groups are asking the U.S. Bureau of Land Management to slow gas development and take other actions.
The BLM says a slowdown would be a last resort under the plans that guide drilling.
State regulators are looking for the U.S. Environmental Protection Agency to set lower national limits for ozone pollution within the next few months.