Friday , August 04, 2017 - 3:02 PM1 comment
Shifting weather this weekend may clear Northern Utah’s air quality concerns — unless it also sweeps in pollution from wildfire smoke.
Hot, dry conditions and a lack of cloud cover in July caused some of the worst summertime ozone levels seen in a decade. While hourly levels have still dipped into the “unhealthy for sensitive groups” range, Bo Call, manager for air monitoring at the Division of Air Quality, said air quality has improved since August began.
“An optimistic person would say ... we’ll be good for foreseeable future,” Call said. “I’m not that optimistic.”
The optimism comes from historical air quality trends in the region. Ozone production typically peaks in July, improves the first couple of weeks of August, then usually (but not always) becomes a non-issue by the end of the month.
The pessimism, however, comes from what Call sees blowing in from up north.
“On the downside, our steering wind directions are changing, coming more from the north, and there are a lot of fires up there,” Call said. “We might start to see elevated particulate levels.”
Particulate pollution is specks of dust and dirt small enough to enter the lungs and blood stream — the same kind of pollution that causes concern during winter inversions.
Fires are currently burning in British Columbia, California, Washington, Oregon and Idaho, and are contributing to smoke blowing into Northern Utah.
Smoke from wildfires can often travel long distances in the atmosphere, Call said.
“Two years ago, we actually were impacted by smoke traced back to ... Russia,” he said. “You could follow the smoke plume on the satellite all the way over here, so it can travel pretty far.”
During bouts of bad smoke pollution, it’s best to “batten down the hatches” and stay inside, Call said. Holing up inside can be dangerous for those without air conditioning, however.
“When we’ve gotten really dumped on by wildfire smoke in the past, the thing that has bothered people in past is using a swamp cooler,” Call said. “It sucks it right in.”
For those who don’t have air conditioning, AirNow.gov recommends seeking alternative shelter during hot weather smoke events.
The National Weather Service, however, forecasts that Northern Utah might see hazy skies through the weekend with limited levels of smoke pollution danger.
“We’ll see a little increase in air pollution, but by latter half of the weekend or early next week, wind should blow out the smoke we have,” said meteorologist Mike Seaman.
That’s largely due to a shifting wind pattern, which will start blowing from the south.
Much of the haze that was visible in Northern Utah in the days leading up to the weekend was caused by local smoke and dust, as well as smoke blowing in from other areas. Ozone pollution is not visible.
“I think most of it is just normal automobile exhaust and smoke from fires,” Call said. “You get smoke from barbecue grills, too, you know ... sometimes it depends on where you’re looking.”
This weekend will also see increased cloud cover during the hottest part of the day, which should continue to improve regional ozone pollution.
“A little cloud cover goes a long way,” Call said. “A lot of ozone (formation) is based on sun intensity.”
Ground-level ozone pollution is caused when volatile organic compounds from fuels or industrial process and tailpipe emissions mix with sunlight.
“It’s a photochemical reaction, so as the sun beats down into the atmosphere where pollutants are trapped, it reacts and ozone forms,” Call said. “Any cloud cover turns the reaction off.”
Ozone pollution oxidizes in the lungs and causes irritation. It can aggravate breath conditions like emphysema or asthma. Infants, young children and the elderly are also more sensitive to the pollutant. Health and air quality officials recommend limiting outdoor activity during the hottest part of the day when ozone levels are high.
Daily air quality conditions and forecasts for Utah are available at air.utah.gov.
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