The Washington Department of Ecology (Ecology) defines designated areas as areas expected to have 24-hour PM2.5 design values exceeding Ecology's healthy air goal of 20 µg/m^3. The form of the PM2.5 design value is the 3-year average of the annual 98th percentile 24-hour average concentrations. These areas were identified using a combination of model output from the Air Indicator Report for Public Awareness and Community Tracking (AIRPACT-4) forecast model and measured PM2.5 concentrations at monitoring sites operated by Ecology and its partner agencies. All input datasets cover the time period July 2014 – June 2017, which was the most recent continuous 3-year period available with minimal wildfire influence. Wildfire data were not removed completely from the dataset; rather, data were chosen and filtered to minimize the influence of wildfires due to inconsistent model performance and extreme outliers during wildfire periods.Design values were interpolated using the following steps:Median daily AIRPACT-4 forecast PM2.5 concentrations were extracted at 4km grid cell centroids.The ratio between the measured 98th percentile PM2.5 concentration (as a surrogate for the 24-hour design value) and the nearest grid cell's median daily AIRPACT-4 forecast PM2.5 concentration was calculated for each monitoring site.The ratios were interpolated across the domain at 4km resolution using Empirical Bayesian Kriging.Interpolated ratios were multiplied by median daily AIRPACT-4 forecast PM2.5 concentrations to yield interpolated PM2.5 design values.Grid cells with design values above Ecology's healthy air goal of 20 µg/m^3 were extracted and dissolved into smoothed polygons. Only polygons with ≥3 contiguous grid cells were retained due to model uncertainty in small areas.Polygons were overlaid with city, census-designated place, and urban growth area boundaries from 2020 Census TIGER/Line files. Where polygons intersected with any of the above census-defined boundaries, the largest of the intersecting boundaries defines the designated area.Ecology plans to update the designated areas layer at least every five years in conjunction with its 5-year Ambient Air Monitoring Network Assessment.
OwnerThe Washington State Department of Ecology - view all
Update frequencyunknown
Last updated10 months ago
OverviewAQAir Quality ProgramECYENVEcologyPM2.5Washington State Department of Ecologydesignated areasenvironmentsmoke
Additional Information
KeyValue
dcat_issued2021-04-23T21:06:29.000Z
dcat_modified2023-05-18T06:42:30.421Z
dcat_publisher_nameJill Schulte, Washington State Department of Ecology
guidhttps://www.arcgis.com/home/item.html?id=20198f0fc6db49a2a097152df5c309b2&sublayer=1
language
harvest_object_id118d2d80-6ed4-468f-80c6-172240855ef8
harvest_source_id03016d16-b963-4f6a-99b0-8a37574f4576
harvest_source_titleWashington Geospatial Open Data Portal