Not just dust in the wind: Pima County airs pollution advisory Tuesday

A high concentration of particulate matter, the term for an airborne mixture of tiny, solid particles and liquid droplets, is hanging over Pima County, triggering a pollution advisory that could stay in place through Wednesday.

The Pima County Department of Environmental Quality issued a "high pollution advisory" Tuesday because of the “unhealthy” levels of dust and other particles found in the air that morning. They’re advising older adults and anyone with heart or lung diseases to limit how active they are outside at least for Tuesday.

“Breathing small particles can irritate the respiratory system and worsen chronic heart and lung diseases," officials said.  The Environmental Protection Agency warns that some particles “can get deep into your lungs and some may even get into your bloodstream,” causing serious health problems.

The EPA also mentions “fine particles are also the main cause of reduced visibility (haze) in parts of the United States, including many of our treasured national parks and wilderness areas.”

Strong winds have passed, and rain is not in the forecast, leaving PDEQ to forecast that wind-blown particles will linger “for a while,” according to their press release.

There are two types of particulate matter or pm. There is PM10, which are particles with diameters 10 micrometers and smaller, which can be inhaled. This might include dust, pollen and mold.

The more harmful types are PM2.5, fine inhalable particles with diameters that are generally 2.5 micrometers and smaller. This includes combustion particles, metals and organic compounds like methane, and can penetrate more deeply into the lungs because of their small size.

Some particles, such as dust, dirt, soot or smoke, are large or dark enough to be seen with the naked eye. Others are so small they can only be detected using an electron microscope, according to the EPA.

Because PM2.5 is finer, it poses a greater health risk as it’s more easily inhaled and travels more easily within the body. However, the EPA warned that some particles less than 10 micrometers in diameter can also cause serious health problems by getting deep into lungs and bloodstreams.

The average human hair is about 70 micrometers in diameter, making it 30 times larger than the largest fine particle, according to the EPA. Particles come in many sizes and shapes and can be made up of hundreds of different chemicals.

Some particulate matter is emitted directly from a source, such as construction sites, unpaved roads, fields, smokestacks or fires, but most particles form in the atmosphere as a result of complex reactions of chemicals such as sulfur dioxide and nitrogen oxides, which are pollutants emitted from power plants, industries and automobiles, according to the EPA.

PDEQ monitors air pollution in our region at 14 air quality monitoring sites, and they provide up-to-the-hour air pollution levels available online.