here are lot of factors that contribute to ozone formation or the lack thereof, and the one that seems to stand out the most is having storms come through on a fairly regular basis. We have had more storms than what we might consider normal. —Bo Call, air monitoring section manager for the Utah Division of Air Quality
SALT LAKE CITY — Frequent storminess this summer has not only helped irrigate farm fields and keep home gardens lush, it is scrubbing the Wasatch Front of harmful pollutants like ground-level ozone.
Bo Call, air monitoring section manager for the Utah Division of Air Quality, said this summer so far has proved to be much milder than what the hottest months of the year typically deliver for ozone.
"There are lot of factors that contribute to ozone formation or the lack thereof, and the one that seems to stand out the most is having storms come through on a fairly regular basis," Call said. "We have had more storms than what we might consider normal."
In July, the state received 131 percent of average rainfall. In some areas, such as Davis and Weber counties, rain topped out at 205 percent of what is typical for July.
Call said all the storminess and cloud cover prevents ground-level ozone from taking hold.
"Because ozone is a photochemical reaction, you have to have sunlight to create it," he said. "The clouds block the sun and turns it off."
While ozone may be inching toward high levels by late morning or noon, the afternoon storminess that has been sweeping in on a regular basis is wiping the pollution slate nearly clean, he said.
"By midafternoon, it seems that is when we are getting these thunder boomers move in, and those turn off ozone production like turning off a faucet. We are not seeing the spikes in the unhealthy levels."
This summer, the division has called 29 voluntary action days, but there has not been a single day where it has invoked mandatory air pollution warnings.
The federal ozone threshold has been breached only six days this summer along the Wasatch Front, compared with 22 last year.
The U.S. Environmental Protection Agency sets the ozone threshold at 75 parts per billion, and Call said the highest value recorded this summer was 77 in Bountiful.
"There have been only a few days this summer (that) have snuck over the limit," he said.
Last year, values clocked in the high 80s some days, Call added.Comment on this story
With August just barely past the midway point, plenty of opportunity remains for bad air days and ozone levels that exceed the threshold.
The trick will be how the weather shapes up and how willing people may be to adjust their personal activities to help cut down on pollution.
This year's Clear the Air Challenge, for example, made a notable dent in air pollution in July.
Results announced Monday show that nearly 6,900 Utahns from all over the state eliminated 2.25 million miles and more than 140,000 vehicle trips — removing a potential of 668 tons of emissions.