Issue with Extracting County-Level PM2.5 Concentration from ISRM Results

[Ana Mazmishvili]

Objective: I want to extract county-level PM2.5 concentration data from the ISRM final result shapefile after running the INmap model for multiple years.

Background and PM25 small values:  My input data included SO2 and NOx emissions from power plants on the East Coast and smokestack info from NEI. I set Primary PM2.5 emissions to 0 since I didn’t have that data for all years. The model output shows extremely small PM2.5 values (e.g., 0.00000000003380400, max = 0.624798). I suspect this is due to missing Primary PM2.5 emissions—can anyone confirm?

Issue with County-Level Extraction: I tried two methods, but both failed:

1️⃣ Python (GeoPandas & RasterStats): Couldn’t get it to work. If anyone has a working script, please share!

2️⃣ QGIS Workflow:

• Converted the ISRM shapefile to raster (.TIFF) using Georeferencing raster unit (Pixel didn’t work) and Used Zonal Statistics to extract mean, min, and max PM2.5 for counties.
• Kept both layers as shape files (county and InMap concentrations) and used Join Attributes by location. 
• Problem in both cases: All counties have identical PM2.5 values, even though ISRM shapefile shows variation.

Questions:

1️⃣ Why are my Total PM2.5 values so low? Is it because I set Primary PM2.5 = 0?
2️⃣ How can I correctly extract county-level PM2.5? What might be wrong with my QGIS zonal statistics approach?

Any suggestions (Python/QGIS) would be greatly appreciated!

I attached a  map for one of the years where I overlayed three files: counties, source points, and concentrations. Any ideas on how to extract mean PM25 data on county level?

Thank you!

I will appreciate your help!

Ana