Why the haze over the Phoenix area lately?

FOX 10 Meteorologist Erica Horvatin is explaining why there's a bit of a haze over the Valley. She details the air quality in the state as the weekend nears. Skies were hazy over the Valley of the Sun on Wednesday, especially noticeable if you looked toward the mountains.

The hazy skies were due to air quality, which was less than healthy, due to pollution , namely, particulate matter. Southern Arizona was not the only area experiencing it, as parts of California , like Los Angeles and Fresno, saw even worse air quality, even being listed in the "unhealthy" group on the air quality scale. The air quality can be directly correlated to the weather pattern across the west this week.



A large area of high pressure is parked over the western United States, and a large area of low pressure is spinning across the northeastern U.S. Underneath a high pressure ridge, air sinks.

This keeps the air closer to the ground and more stagnant. It can also trap pollutants close to the ground. Air rises under low pressure troughs, which in turn keeps the air flowing and moving.

The northeastern U.S. had no air quality issues on Wednesday.

The pollution that is being trapped near the ground out west, especially around big cities, is comprised mostly of particulate matter. According to the Environmental Protection Agency, particulate matter includes dust from unsealed roads, smoke from fires, car and truck exhaust, and industry. More specifically, the matter is made of heavy metals, dioxins, furans and benzopyrenes, which are compounds, and which are all carcinogenic.

Moderate levels of particulate matter are not a huge concern, and you can still spend time outdoors. However, high levels, identified when the EPA deems the air quality "unhealthy," can be dangerous to human health, causing respiratory issues and other bodily reactions. The unhealthy air quality is especially common in big cities during the summertime in the Northern Hemisphere, but with warmer than normal temperatures, and a stationary weather pattern, we can see it during the winter too.

A cold front will arrive in the southwest next Monday and Tuesday, which will move the air along, and improve air quality conditions..