The tsunami of West Coast wildfire smoke that inundated Utah on Friday thinned out a little by Saturday morning, but air quality along the Wasatch Front remained bad enough to warrant spending the weekend indoors.
Salt Lake City’s air quality for a time was the worst in the world among major cities when levels of fine particulate, or PM2.5, spiked above 100 micrograms per cubic meter, more than three times the federal health standard, blotting out the sun and views of the mountains. On Saturday, Utah’s capital dropped to the bronze medal position for filthy air, behind Lima, Peru, and ahead of Kabul, Afghanistan.
“A cold front Friday morning brought in an abundance of wildfire smoke that resulted in some of the coolest temperatures in well over a month,” the National Weather Service tweeted Saturday. “While the cold front provided slightly cooler temperatures, smoke it brought in played a bigger role.”
The 62 degrees registered on Saturday morning for Salt Lake City was the lowest temperature reading since June 13, according to the weather service.
Unlike Utah’s winter inversions, this pollution cannot be avoided by heading into the mountains. Laden with substances harmful to human health, the smoke is hardly confined to low elevation areas, but extends far off the valley floors.
On the bright side, Salt Lake City’s ozone levels, which are typically elevated in the summer, were below unhealthy levels when the smoked arrived Friday, but that was changing Saturday afternoon. By 2 p.m., Wasatch Front monitoring stations were recording unhealthy levels of both PM2.5 and ozone, setting up residents for a double dose of pollution.
When both types of air pollutants are present, it may be wise to avoid the outdoors altogether, according to Daniel Mendoza, a University of Utah research professor of atmospheric sciences. Inhaling ozone can inflict what amounts to a sunburn on the respiratory tract, reducing the ability of the lung tissues to produce mucus.
“Your lungs are not going to lubricate correctly and then they’re not going to expel the PM2.5 you breathe in. It’s basically a double whammy. Normally when you are exposed to PM2.5 during a [winter] inversion you still have mucus and lubrication to push it out,” Menodoza said. “But when your lungs are burning and they’re not producing that mucus and phlegm to remove it, you are basically getting PM2.5 gets inside your lungs and it could go much deeper than if it was just during a normal inversion.”
PM2.5 is a pollution category that includes tiny particles that are less than 2.5 microns in diameter. The smaller the pollution particles, the more dangerous they are because they can penetrate deeper into tissues.
“Wildfire smoke particles are significantly smaller. PM2.5 is catchall phrase for anything that’s 2.5 microns or smaller. Depending on the type of fire, it could be what are called ultrafine particles, or PM1, two and a half times smaller or 40% as large,” Mendoza said. “That can go really deep and potentially cross the blood brain barrier.”
Under normal summer conditions, Mendoza recommends exercising outdoors in the mornings, when it is both cooler and ozone levels are always lowest. But when wildfire smoke is present, as has been the case much of this summer, it is better to get out later in the day when the particulate pollution isn’t as concentrated near the ground.
“So there’s really no good time. Later on in the day the wildfire pollution will be lower because [the smoke is] more elevated. But then the ozone will be higher,” Mendoza said. “So you literally have to pick your poison at this point if you want to exercise outdoors.”
On the Wasatch Front, Saturday morning broke with some marginal improvements, but another wave of smoke was forecast to hit Sunday. The smoke is coming from the Dixie and other large fires raging in Northern California. Much of the West is blanketed in smoke blowing from massive fires across California, Oregon, Washington and Montana.
As of Saturday, according to the National Interagency Fire Center, there were 107 large fires burning in 14 states, involving nearly 2.2 million acres.
Utah has largely evaded this summer’s epidemic of burning; currently, the Beehive State is reporting just one large fire. The Morgan Canyon fire was sparked on June 18 by a plane crash in the Stansbury Mountains. According to Utah Fire Info, it is 90% contained after burning on about 500 acres.