Here’s the weekend’s weather outlook: A cough followed by a cold. The pollution that’s been clouding the Valley’s skies this past week is expected to last through at least this afternoon, putting people with delicate respiratory systems at risk.
Then, a cold front is forecast to sweep through Arizona tonight. Breezes should blow away the bad air while low temperatures drop into the mid- to upper 30s by Monday morning.
"But it’s not going to take long for (warm temperatures and pollution) to build back up again," National Weather Service meteorologist Leslie Wanek said. "This is how it goes for the winter months in Phoenix — and any Valley location, really."
Since Tuesday, health officials have been issuing warnings about excessive levels of smoke, pollen and dust in the air. These pollutants are called particulates and consist of matter measuring less than 10 microns across. For
comparison, a human hair is 100 microns wide.
When inhaled, particulates can increase a person’s susceptibility to respiratory infections and aggravate existing respiratory conditions, such as asthma and chronic bronchitis.
A weather phenomenon known as a temperature inversion traps pollution in the Valley’s air. An inversion occurs when a layer of warmer air in the atmosphere traps cooler air beneath it. The warmer air acts as a lid, keeping pollution contained.
This past week, the pollution didn’t climb far beyond moderate levels because the inversion was weak, and the Thanksgiving holiday meant Thursday and Friday didn’t have the twice-daily rush hours.
Still, the Arizona Department of Environmental Quality has extended its health watch through today.
Also, Maricopa County residents are being asked to voluntarily forgo using their fireplaces after two days of restrictions on woodburning stoves and fireplaces. Violators of the county’s no-burn ordinance are first warned, then hit with fines up to $100.
"We were happy we could lift it on Thanksgiving Day, because it is nice to have," said Holly Ward, spokeswoman for the Maricopa County Air Quality Department. "But it is in everybody’s best interest, during these high-concentration times, to avoid polluting."