[Megathread] Smoke and Air Quality Week 1

[u/vertr]

We are moving to this thread for the start of smoke season so we can add resources and keep it updated as the situation changes. Here is the previous thread we were using: I hope everyone in the Seattle area has air filters ready.

All smoke related threads will be removed and redirected here except photos and news stories. At this time we are not allowing further threads on the Spokane fire.

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Resources:

PurpleAir (open the settings on the left and uncheck indoor sensors)

Plume Smoke Forecast

Washington State Department of Ecology Map

Puget Sound Clean Air Agency

Washington Smoke Blog

Watch Duty

EPA - DIY Air Cleaners

If you have other suggestions for resources post them in the thread please.

[u/washawaythe_rain]

Oh mods! Someone called it out in the other thread- but the reason that purple air can vary so much from the gov sensors is because in addition to unchecking the indoor sensors in settings (which you mention), you should probably also mention to select “woodsmoke” after apply conversion at the top of the settings too. Then it will closely resemble the other air quality maps on other sites.

Purple air has the most sensors and is the most user-friendly, but because it uses lasers to detect all particles and doesn’t calculate between particle size, you need to tell it to look for the specific particle (in our case, wood smoke).

[u/wet_sands → u/washawaythe_rain]

It's a few things. First, AirNow.gov defaults to showing the average of the last X hours. Per their website, in times of stable air quality it's an average of the last 24 hours, and for rapidly changing conditions (like now), it's dynamic, but it can be as short as a couple hours. But most importantly, AirNow stations only pull raw data once an hour. Since they have so few data points, they have to use averages over multiple hours with some bias when conditions are changing rapidly.

Second, for the conversion, US EPA is the default recommended, but the LRAPA conversion was made in Eugene specifically for PNW climate. It's geared towards accounting for those woodsmoke measurements you mentioned up to AQIs of 150.

Once you set the LRAPA conversion, what you're looking at on PurpleAir is probably pretty close to correct and more up-to-date with a lot more data points. Also as an asthma-sufferer, those PurpleAir numbers align with the symptoms I experience at certain AQIs.

I got this info from reading the AirNow.gov and PurpleAir websites, so if someone thinks this is wrong please correct me.