Hazardous Air Quality in Phoenix on New Year's Day

If we had to guess, most of you were awake as the clock struck midnight, either because you were celebrating the new year or from the noise of all the fireworks. Even if you weren't awake, you likely saw and smelled the aftermath of the celebrations as the air quality in Phoenix on Jan 1st reached Hazardous, based on the Air Quality Index (AQI). The photo above was taken from Silly Mountain (in the far East Valley) and shows the top of Camelback Mountain sticking out of the layer of smoke during the morning of January 1st.

The AQI for smoke levels (PM-2.5) is based on a 24-hour average from midnight to midnight. Looking at this New Year's Day (Jan 1st), the West Phoenix PM-2.5 (smoke) monitor exceeded the 24-hour health standard set by the EPA within the first hour of the day and was in the Hazardous AQI category (the highest the scale goes) by the 7 am observation. The graph below shows how quickly the West Phoenix monitor reached the Hazardous AQI level (based on the 24-hour average starting at midnight). The seven other PM-2.5 (smoke) monitors in the Valley exceeded the standard by 4 am, with all of them being in the Unhealthy or Very Unhealthy AQI category by 9 am.

The sheer number of fireworks being ignited, combined with smoke from fireplaces and firepits, mixed with very calm weather conditions and strong inversions, allowed all the smoke to get trapped right near the surface.