Arkansas has posted yet another ozone season below the federal limit for ozone pollution.
After years of higher ozone readings and issuing occasional Ozone Action Days, even the parts of Arkansas traditionally most susceptible to ozone pollution are experiencing levels below the strictest federal standards.
That's because of high fuel standards, lower emissions from vehicles, reduced usage of coal-fired power plants and changes in the trucking industry, officials said.
"Generally, it's difficult to pinpoint with accuracy one particular reason why we continue to see the trends that we are seeing, but I will say I'm pleased that they continue to drop," said Stuart Spencer, the Arkansas Department of Environmental Quality associate director overseeing the office of air quality.
"It's better than it's ever been," said Woody Wheeless, the county judge of Crittenden County, which has a history of noncompliance with ozone standards. The county continued its recent success with ozone levels this year.
Ozone season is considered to be from May 1-Sept. 30, when the weather is hotter and air is likelier to interact with car exhaust and other emissions to create ozone.
Crittenden County, on the edge of the heavy-traffic and high-ozone Memphis metropolitan area, was out of compliance a few years ago. It was subject to greater scrutiny and regulations as a result -- a burden the county no longer has to deal with.
The county and the Arkansas Department of Environmental Quality are pursuing a voluntary plan to reduce ozone by lowering nitrogen oxide levels through more efficient fuels and infrastructure, improved industry equipment, carpooling and public transit, among other things.
Wheeless attributed the recent success to lower emissions from vehicles and increased engagement with the trucking community in the trucking-heavy Memphis area.
West Memphis has three major truck stops where hundreds of trucks every day park for the night while their drivers sleep, Wheeless said. Officials have reached out to drivers and industry groups, urging them to turn off their truck engines overnight and use other means of controlling temperature -- such as a generator -- while the driver sleeps.
Statewide, Spencer said, Arkansas vehicles and power plants have been emitting fewer pollutants. Arkansas power plants participate in the U.S. Environmental Protection Agency's Cross-State Air Pollution Rule, trading nitrogen oxide emissions credits with other states. Because emissions have decreased, he said, he suspects utilities may be trading away more credits for emissions than they are buying.
Ozone occurs naturally in the atmosphere. When car exhaust and industrial emissions react to high temperatures and sunlight, ozone forms at the ground level, where it is often referred to as smog.
Exposure to ground-level ozone can intensify allergies or respiratory problems for people who already have them. High levels of ozone can create respiratory problems for anyone who goes outside.
The EPA's standard is 75 parts of ozone per billion parts of air, measured by taking the fourth-highest daily ozone level each year for three years and averaging that number. The standard was set to change to 70 late this year, but EPA Administrator Scott Pruitt has delayed the standard another year.
When calculating 2015, 2016 and 2017's readings so far, the Marion air monitor has detected an ozone level of 67 parts per billion, according to data collected by the Arkansas Department of Environmental Quality. That's the highest in the Memphis area, which has four other monitors. Those, all located farther east, determined averages of between 62 and 66 parts per billion.
Marion only had one reading above 70 parts per billion. On June 9, the monitor detected 82 parts per billion, high enough for a classification of "unhealthy for sensitive groups."
Central Arkansas' two ozone monitors have detected ozone levels of 61 and 63 parts per billion, and Northwest Arkansas' two monitors read 59 and 60 parts per billion.
Northwest Arkansas had no readings above 63 parts per billion all ozone season. Central Arkansas had only one reading above 70 parts per billion -- 75, detected on June 9 in North Little Rock.
Ozone readings below 60 parts per billion are considered "good," according to the EPA. Readings from 60 to 75 are considered "moderate," and readings from 76 to 95 are considered "unhealthy for sensitive groups." Above 96, classifications range from "unhealthy" to "hazardous."
The readings are good news for Wheeless and county leaders, who are trying to avoid EPA scrutiny and increased regulations to lower emissions, as well as for others who live there.
"I think it's important, not only for our county, that we've got quality air that the public's breathing," Wheeless said.
If people want the environment to take care of them, Wheeless said, they've got to take care of the environment. He said he expects the trend of lower ozone to continue and that he doesn't see any reason why it shouldn't.
"We seem to be hitting on something that's making it work," he said.
As for the future, Spencer said he couldn't speculate.
"It's difficult to say, just because there's a large part of ozone that's contingent on transport," he said.
Those trends can change, he said, plus some people would like to see the EPA pay more attention to emissions in international transport.
Metro on 10/16/2017