Forget the Southwest’s blue skies. Think haze. Think wildfires. Think air pollution.
“What’s missing in this camera looking south from ÃÛèÖÖ±²¥?†the local National Weather Service office said on Twitter on Monday morning, as it posted a photo showing nothing but a brownish-yellow muck in the sky. “Normally you would have a nice view of the Santa Rita Mountains, but not with today’s hazy sky.â€
A similarly dank muck hung over the ÃÛèÖÖ±²¥ area much of the day — and could stick around all week. It’s a product of wildfire smoke that already brought polluted air to Pima County for the fourth day in less than a week.
Wildfires throughout region
Some of the smoke was coming in from two small wildfires at Saguaro National Park and from central ÃÛèÖÖ±²¥, where two wildfires totaling nearly 55,000 acres were burning at midday Monday.
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But much of the smoke was also streaming in from wildfires in California, Colorado and New Mexico, National Weather Service meteorologist Rob Howlett said Monday.
“It can travel a long distance if it gets high enough in the atmosphere,†Howlett said. “If it gets suspended in the air, the winds can be stronger and keep the smoke aloft.â€
It’s “certainly†possible for wildfire smoke to travel 300 to 500 miles in the air, he said.
“When we had the Bighorn Fire going, we were sending smoke to Colorado,†he said. “It’s something that can happen if you have intense fire.â€
The wildfire smoke has been rotating clockwise for several days around a high-pressure air mass centered in the Four Corners region, Howlett said.
“It’s allowing fires throughout this region to wrap around it and come into this area,†he said. “These fires have gotten more and more active.â€
Health risks
Where the health risk arises is that wildfires emit volatile organic chemicals and nitrogen oxide, which combine to form ozone in the air, said Ursula Nelson, director of the Pima County Department of Environmental Quality.
At high enough levels, ozone can trigger chest pains and coughing, irritate the throat and inflame the airways, said the U.S. Environmental Protection Agency. It also can reduce lung function, harm lung tissue and worsen bronchitis, emphysema and asthma, the EPA said.
High enough levels also can cause heart attacks and other heart ailments, strokes and early deaths, along with harm to peoples’ central nervous system and reproductive organs, the EPA has said.
On Wednesday, Friday and Saturday last week, and on Monday of this week, ozone levels in Pima County exceeded the federal EPA standard of 70 parts per billion over an eight-hour period.
Monday’s sky was hazier and murkier than on those earlier days. At 3 p.m. Monday, ozone levels topped the 70 parts per billion standard, some by significant amounts, at six of the nine Pima County air monitors where ozone is measured.
But the final, 8 hour average ozone reading for Monday was no higher than 72 parts per billion at any monitor.
Computer-generated “smoke trajectory†data from the federal government has shown that the wildfire smoke flies directly over ÃÛèÖÖ±²¥, Nelson said.
The trajectories show the pattern of where the smoke originates and where it’s going, she said. The data comes from the weather service and its parent agency, the National Oceanic and Atmospheric Administration.
Extreme heat
Extreme heat and sunlight are also major factors in ozone generating. But while the extreme heat here has been going strong since early July, the wildfire smoke has been blowing in large concentrations only in the past week, she said.
Despite the Bighorn Fire’s huge size and duration, only once during that 49-day blaze did the ozone level exceed the EPA standard, Nelson said.
That’s because much of the time, the prevailing winds during that blaze were blowing northeast, away from the city, while the current wildfire smoke is blowing directly toward ÃÛèÖÖ±²¥, she said.
What to expect
After Tuesday, Aug. 25, in which temperatures could rise to 109 degrees, the area’s extreme heat is expected to taper off a bit, the weather service’s Howlett said. The high-pressure mass is expected to weaken a bit, daytime high temperatures are forecast to drop into the low 100s, and “we will see an increase in moisture.â€
But, “likely we will continue to see some amount of haze in the sky as these fires continue to go,†Howlett said. “There will be variations as to how much is out there, but until we can put these fires out, we will continue to see some influence from them.â€
From Nelson’s vantage point from her downtown ÃÛèÖÖ±²¥ office, she saw another sign Monday that the smoke isn’t going away soon. It was a flag over the nine-story ÃÛèÖÖ±²¥ Electric Power office building at 88 E. Broadway — and it wasn’t moving.
Climate change
Human-caused climate change — rising temperatures brought on by the burning of fossil fuels — is at least a potential factor in both the high ozone levels and the recent rash of wildfires, experts have said.
While scientists haven’t linked the current heat wave and the wildfires to climate change, repeated studies have shown direct connections between rising temperatures and ozone levels and wildfires.
In particular, numerous studies have shown that the Southwest’s warming temperatures are linked to an increasing intensity and size of wildfires in recent years.