Wednesday, August 30, 2017

8/30/2017 Air Quality Monitoring Deep Dive

This post is meant as an explanation of how to better understand some details of the air quality monitoring information you see as colored dots on the smoke blog map and on the Washington Dept. of Ecology air quality map (available at See the questions in the boxes on the image below. Read on if you'd like to know the answers.

1.  Why are the dots over Malaga and Quincy on the WA Ecology air quality map showing good (green) air quality when others nearby are red or orange?

Answer: Most of the dots on the Ecology map show air quality conditions for PM2.5 (fine particulate matter) which is a really good indicator of how much smoke is in the air, but some of the dots represent monitors that measure a different component of air quality. The monitor in Malaga measures SO2 (sulfur dioxide), and the monitor in Quincy measures NO2 (nitrogen dioxide) neither of which are significant components of wildfire smoke. There are also a few monitors around the state that measure O3 (ozone) including one north of Spokane that is green right now whereas other monitors nearby are orange or yellow. Ozone levels can go up due to wildfire smoke but generally not until late in the afternoon.

You can find out what is being monitored at a site you are interested in by clicking on the colored dot on the Dept. of Ecology air quality map ( and then on “View Site Information” in the next pop-up box as shown in the figure below.

Note: All monitors shown on the Smoke Blog map are PM2.5 (fine particulate) monitors.

How to find out what pollutant is being monitored at a location on the Dept. of Ecology map.

Most monitoring sites on the Dept. of Ecology map measure PM2.5 but not all.
2.  Why do the two maps (Dept. of Ecology vs. Smoke Blog) show different warning levels for the same locations as in the example in the first figure where Ellensburg is orange on the Ecology map and yellow on the Smoke Blog map?

Answer: There are two different air quality warning indices in action here – the WAQA vs. the AQI. The federal Environmental Protection Agency developed a scale called the Air Quality Index (AQI) that applies across the country. Washington Department of Ecology wanted an index that was more protective of public health so they developed the Washington Air Quality Advisory (WAQA) that warns the public of possible health risks at air pollution concentrations lower than the AQI. So if the two maps are showing different warning categories, the WAQA scale will warn of greater health risk than the AQI. 
3.  Why are some monitoring sites indicated by triangles on the Smoke Blog map but don’t appear at all on the Dept. of Ecology map?

Answer: The Forest Service has invested in a national cache of portable air quality monitors that can be sent to communities that are impacted by smoke but not represented by state monitoring networks. In Washington at the moment we have one of these monitors in three small communities: Mazama, Tonasket, and Metaline Falls. These sites show up on the Smoke Blog map as triangles but do not appear on the Dept. of Ecology map.

Department of Ecology also has some mobile monitors to deploy when needed. Currently they have mobile monitors placed in White Salmon, Cle Elum, and Newport. The Dept. of Ecology mobile monitors show up on both maps as circles so are indistinguishable from other monitoring in the state although the sites will eventually be removed when the risk from smoke is over.
The picture below shows the portable air quality instrument that was deployed in Mazama near the Diamond Creek fire. Learn more about the instrument and how it is used at the video available here: 

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