Air Quality Index

The Air Quality Index (AQI) is a numeric indicator of local air quality. Since last Thursday night, our AQI has been in the 500 to 526 range. The range only goes up to 500. Anything above 300 is considered hazardous to health for all.

We live in the area of the fires in Oregon.

We’ve been sealed up inside your home since Thursday. Fortunately, there is little smoke smell inside as our house is sealed very tight – but outside it was extremely difficult to breath. The smoke led to headaches, fatigue, sore throat and a slight shortness of breath – classic symptoms of smoke inhalation, I am told.

As of right now, the AQI has fallen to 169 which is a noticeable improvement, however this is not yet to a normal range.

The fire storm was caused by an early Arctic air mass (high pressure) descending south from Canada. The winds blew from the colder, high pressure to the warmer, low pressure to the south and on the west of the Cascades. This caused very strong winds to blow for 1-2 days, crossing mountain ridges at 55 to 75 mph and pouring down west side mountain canyons.

Routine summer thunderstorms had started fires on August 16th, fires which had been fought since then. The Lionshead fire had grown to about 22,000 acres – but then when the winds hit, exploded by over 100,000 acres in about 24 hours. Similarly, Beachie Creek Fire had also started on August 16th and was at only 500 acres when the winds hit – and it too was soon over 100,000 acres (now 190,000 acres) in size.

The cold air mass poured into the valleys and plains – creating an inversion layer of colder air that would not mix with the warmer air above. This trapped the smoke near the ground.

Yesterday – and likely again today – we will see the effects of the weakening inversion. Yesterday, AQI fell to around 250 in the afternoon but as the air mass cooled in the evening, it went back to 468 where it remained overnight. Suspect today’s lower reading will do the same this evening and repeat this pattern until late in the week when a fall weather storm system enters the area, delivering rain and breaking the inversion layer.

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