Windy AQI PM2.5 consistently way lower than other sites and experienced air quality

gkiritz

I live in Leavenworth WA, and we consistently experience smoke during late summer. Currently, the following sources are showing our air quality for today:

Windy: 6 µg/m3 - about 25-27 AQI.
AirNow.gov: 85 AQI (28.2 µg/m3)
PurpleAir: 83 - 192 AQI (28 to 135 µg/m3)
IQAir: 94 - 160 AQI (32.5 to 74.8 µg/m3)

This has been a trend for the last month, and often we are experiencing noticeably unhealthy levels (heavy smoke smell, headache, irritated eyes, etc) when Windy says our PM2.5 levels are close to 0. Anyone able to help me understand why Windy is consistently showing much lower levels than experienced or observed on other sites? Thanks.

Korina

@gkiritz Hello, are comparing forecast PM2.5 or measured data from stations? If it is forecast, then data may differ. Please provide more details.

gkiritz

@Korina My understanding is that Windy shows forecasts from Copernicus and these other sources are showing both observations from sensors and forecasts. So I guess the question is, why is the forecast consistently off by 300-400%? Maybe this is an issue with the data sourcing.

idefix37

@gkiritz
You compare satellite PM 2.5 measurements (at a very low resolution) with air quality stations data located in a valley surrounded by mountains. The satellite cannot " see " a very local concentration of pollution.
You better rely on the 2 Air quality stations shown by Windy in Leavenworth (need to zoom in).

And see the small i at bottom right corner of your screen or About this data in the mobile app to get more information on this layer, where it is said that " Due to the horizontal resolution of the systems used by CAMS, it is not possible to represent local effects due to the immediate vicinity of sources (high-traffic road, industrial plant...) ".