Demo: Reconcile intake fraction (iF) for primary PM2.5

## Summary

For primary PM2.5, where:

* `CMAQ` = 1x1km modeling conducted by Air District, using CMAQ, in 2021/2022; and
* `InMAP` = **demo** dataset supplied by UW
* except slight change to population `P`; see Details, below

... we have:

:warning: Improvements to this table, with updated values, are posted in the comments below. Original results retained here to preserve the record of the discussion. ⚠️

|variable | CMAQ| InMAP|unit |
|:--------|-----:|-----:|:---------------|
|P, population | 7.57| 7.63|Mperson |
|C, pop-wtd concentration | 4.40| 1.43|ug m-3 |
|Q, breathing rate | 14.50| 14.50|m3 d-1 person-1 |
|E, emissions | 30.79| 44.42|t d-1 |
|iF, intake fraction | 15.69| 3.56|ppm |

... and the ratio of the intake fractions is a bit larger than 4:1.

Code to replicate the table above is in [scratch-demo-PM25-iF.R]. It pulls from intermediate datasets found in [Build/], themselves assembled by code in [Make/].

## Details

For the `InMAP` results above:

- San Francisco Air Basin ("SFAB") defined to be a selected set of ISRM cells
- See [US_SFAB_cell_geometries] for effective definition
- `PM25` emissions summed over those "SFAB" cells
- Raw values obtained from [ca_nei.csv.gz], as documented in [Readme.xlsx]
- Tabulated at cell level (across all source types) for easy reference in [SFAB_ISRM_demo_ems_data]
- Population-weighted `PrimaryPM25` concentration across same "SFAB" cells
- Calculated using 2020 tract-level Census population counts
- For consistency with BAAQMD CMAQ modeling runs
- But using 2010 (vs 2020) counts shouldn't make a large difference at this spatial scale for this summary statistic
- See [SFAB_tract_2020_raceeth_data] for Census 2020 tract-level population counts
- Just aggregate across `pop_h*`; numbers are a partitioning and will sum to a correct total (nothing is double-counted)

[scratch-demo-PM25-iF.R]: ../blob/master/Scratch/scratch-demo-PM25-iF.R

[Build/]: ../tree/master/Build
[Make/]: ../tree/master/Make

[US_SFAB_cell_geometries]: ../blob/master/Build/Geodata/US_SFAB_cell_geometries.geojson
[US_ISRM_demo_ems_data]: ../blob/master/Build/Demo/SFAB_ISRM_demo_ems_data-pol.csv
[SFAB_tract_2020_raceeth_data]: ../blob/master/Build/Population/SFAB_tract_2020_raceeth_data.csv

[ca_nei.csv.gz]: ../blob/master/Data/UW/2022-03-07/ISRM/ca_nei.csv.gz
[Readme.xlsx]: ../blob/master/Data/UW/2022-03-07/ISRM/Readme.xlsx

[apte2019method]: https://ww2.arb.ca.gov/sites/default/files/classic/research/apr/past/17rd006.pdf