The combination of good weather (a high pressure system), wildfire smoke from British Columbia, and fireworks led to very high air pollution last night in the Puget Sound area. This was particularly true in Pierce County where air quality was in the Very Unhealthy range earlier this morning. Thankfully air quality has greatly improved and most areas are Moderate.
With another hot day today we should see good vertical mixing – when the air near the ground heats up and rises, bringing smoke with it. This will dilute the smoke and continue to improve air quality.
The majority of the pollution we saw last night was due to fireworks. The wildfire smoke from British Columbia, which arrived earlier in the day on July 4th, only pushed us from Good to Moderate. We don’t expect more of that smoke in the near future, though the fires are still burning and the possibility of smoke later on remains.
Given that, we may see another (smaller) pollution spike tonight depending on how many fireworks are left over.
Also, there is a wildfire near Shelton, the McEwan fire, that started yesterday afternoon and has burned around 250 acres as of last count. Crews are working to create fire lines to prevent the fire from spreading. Air quality in Shelton is currently at Unhealthy For Sensitive Groups and smoke impacts are expected to persist for the time being. So far we expect impacts to be local, but models show that some smoke could reach Pierce County overnight.Sensors in Skamania county along the Columbia river are showing USG smoke impacts from the Tunnel Five fire.
We will continue to monitor the situation and update as needed.