Charlie Brennan | Boulder Daily Camera, Colo.
A Boulder-based researcher has authored a new study showing that intrusions of ozone-rich air from the stratosphere can compound the ground-level challenges in meeting federal ozone standards in Las Vegas — and the same factors can influence conditions in Colorado.
Andrew Langford, a research chemist in the Earth System Research Laboratory at the National Oceanic and Atmospheric Administration, is the study’s lead author.
“It’s a problem that affects the whole intermountain West,” Langford said. “Certainly, we’ve seen these things in the Boulder-Denver area.”
The 2013 Las Vegas Transport Study, published online this month in the journal Atmospheric Environment, was based on data collected in May and June 2013 in the area of Mount Charleston, in Clark County, Nevada, west of Las Vegas.
Much of the West is at a higher average elevation, putting people closer to the stratosphere, a region about eight to 30 miles above the Earth that holds more than 90 percent of the atmosphere’s ozone. That ozone is considered beneficial, in that it filters harmful ultraviolet radiation from the sun.
But ozone at the Earth’s surface is considered a pollutant and a health threat. Under the Clean Air Act, the Environmental Protection Agency has set the eight-hour ozone standard at 75 parts per billion.
The Las Vegas study examined the phenomenon of stratospheric intrusions of ozone, pushing into the troposphere, and its effect on ozone levels at ground level.
“In the western U.S., we’re near the end of the Pacific storm tracks, and when these storms that come across the Pacific hit the northwest, they often form what’s called a tropopause fold,” Langford said.
The resulting tongues of stratospheric air plunging toward the Earth’s surface, the study found, has the effect of boosting the ozone level on the ground. With the normal background level of ozone in the Las Vegas area at 50 to 60 parts per billion, the stratospheric intrusions pushed it at times over 80 parts per billion, exceeding the federal standard.
The EPA is under federal court order to draft tougher ozone standards by Dec. 1, likely lowering the number to 60 to 70 parts per billion.
Because of the naturally occurring intrusions of ozone from the stratosphere, when the standards are made tougher, “These exceedances will be really common in the springtime, May and June (for Las Vegas), and it could be significant here as well,” Langford said.
Scientists from the University of Colorado’s Cooperative Institute for Research in Environmental Science, and other offices, also participated in the study.
“We still have a lot of data that we need to keep looking at from the study, part of which is also looking at the effect of southern California wildfires on air quality up there,” Langford said. “There’s enough data there to keep us busy for quite a while.”
This article was written by Charlie Brennan from Daily Camera, Boulder, Colo. and was legally licensed through the NewsCred publisher network.