Air quality advisory

Published: Nov. 17, 2015 at 9:24 PM MST|Updated: Mar. 2, 2018 at 4:11 PM MST
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The cold and dense air that moved into Arizona has caused some more trouble other than freezing temperatures.  As the cold air sank to the ground last night, warmer air gets stuck above it, creating what's called an inversion.

A temperature inversion means the air is usually stagnant, which keeps dust and haze closer to the surface, rather than rising and mixing with the air above.

You may have notice a slightly hazy sky today around Tucson.  This image from PDEQ (Pima Department of Environmental Quality) is from downtown Tucson, looking east.  The haze has decreased through the day, as the air heated up.

image: PDEQ

PM stands for particulate matter and the higher the number, the more dust and haze is in the air. PM 2.5 are tiny particles, and PM 10 are slightly larger particles.  The PM 2.5 dropped from 85 this morning, to 51 this afternoon.  Once it reaches 101, individuals who are sensitive to air pollution may experience health effects.

Right now, levels are pretty low.  Only highly-sensitive individuals will need to limit themselves outdoors.  We'll keep an eye out for another hazy morning tomorrow, as the cold air could create another inversion tonight.

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