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With some wildfire smoke already swirling around the Wasatch Front, air quality experts say fireworks are the last thing the Salt Lake Valley needs this weekend.

Fireworks are typically a localized, temporary problem for air quality, said Bo Call, who oversees monitoring in the state Division of Air Quality (DAQ). Though usually short-lived, the smoke from fireworks has caused air quality to worsen, reaching the "very unhealthy" or "purple air" range for a few hours on the evening of July Fourth.

That smoke doesn't typically travel far from the source, Call said. A few hours of significantly high particulate pollution might register on the Fourth, he said, if fireworks are set off near one of the state's monitors.

But it can create an issue for people near the display.

"Fireworks in particular are a short-term, acute problem that comes for hours and then is gone," said Robert Paine, a physician who specializes in the respiratory system at the University of Utah Hospital. "But for many people with lung disease ... it's enough to trigger a problem that doesn't go away as soon as the pollution goes away. It can continue for a few days and even lead to trips to the emergency room."

Paine said smoke from fireworks can cause his patients to have more problems with coughing, shortness of breath and fatigue. He said they often have to stay inside on Independence Day to avoid the smoke.

"It is not a trivial health burden," he said. "Burns and fire are obviously a huge risk [of fireworks], but the pollution piece is important and should be taken into account."

Donna Spangler, a spokeswoman for the Department of Environmental Quality (DEQ), suggested residents skip individual or neighborhood fireworks this year in favor of the large, commercial or community displays.

"It's just a simple matter of the closer you are to it, the more you are going to be impacted," she said. "And … if everyone is doing their own thing and setting off fireworks, what it's going to do is make the air quality even worse."

"Yellow air" is already forecast for the weekend by the Department of Environmental Quality. According to the color-coded Air Quality Index system, yellow air indicates elevated levels of pollution that have not yet exceeded the point at which the Environmental Protection Agency believes health impacts occur.

Call said the DAQ expects yellow air conditions this weekend on account of the hot, dry conditions in the forecast, which make the formation of ozone more likely. Smoke from regionwide wildfires — although some has begun to infiltrate the Wasatch Front — was not factored into the air quality forecast. The impact of wildfires on air quality can be difficult to predict, he said.

"I've seen it both ways," Call said. "So much smoke that you can't see the other end of the valley in Salt Lake, and the monitors don't even move. Other times, it has had an impact and the readings have spiked and gone up."

But if wildfire smoke does drift into the valleys this weekend, Paine said that will only add to the impact of the fireworks on his patients. And ozone, which forms in the atmosphere when sunlight causes other common pollutants to react with one another, is a double whammy.

"They impact different parts of the airway, and you get a double hit when you have both ozone and particulate," he said. "It's not common to get the combo, but it happens sometimes … in the summer here, when we have ozone and fireworks or wildfire raise the potential for the combination."

Paine said he agreed with the DEQ's advice to attend commercial fireworks displays rather than buying individual incendiaries. Not only are the spectators at these events usually farther away from the smoke, the fireworks are launched higher into the air, so the smoke dissipates faster and has a smaller impact.

"Any of the ground-based things that spew a lot nearby will give a lot of smoke that may impact not only the people doing it, but folks nearby in the neighborhood," he said.

Those with asthma or other respiratory conditions or sensitivities, he added, "should probably enjoy the fireworks through the window of an air-conditioned building."

Twitter: @EmaPen