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The analytic steps for assessing the total health impacts from air pollution in BenMAP are nearly identical to those for assessing the health impacts from incremental changes in air quality. These steps differ for monitor and model data.
If you are using monitor data, you can perform a 99% rollback using the monitor rollback function. BenMAP is currently unable to process a 100% rollback, but 99% is a close approximation. This provides an estimate of the total health burden associated with air pollution. Because some amount of air pollution may be naturally occurring (i.e., nonanthropogenic), I recommend that you specify a background concentration for this natural air pollution fraction, which I discuss below in the discussion of model data. The 99% rollback will then rollback each monitor value to roughly the background concentration, so that your air quality delta represents the total anthropogenic burden of air pollution. The screenshot below displays this portion of the analysis in BenMAP.
If you are using model data, you still start your analysis with one .csv file that contains your baseline air quality grid (e.g., observed concentrations in 2015). As an example, please see the screenshot below:
This file will serve as your baseline air quality data. You can now create a second .csv file to use as your control data file. Change all data in the “Values” column to whatever concentration you would like to use as a background (non-anthropogenic) level. The lowest observed concentration in the Krewski (2009) study is 5.8 µg/m3, so this is one commonly used option, as you noted in the Punger and West (2013) study. Alternatively, you may select a background of 0 µg/m3 if you wish to estimate the impact of any and all ambient particulate matter (anthropogenic or otherwise). See the screenshot below for an example.
Using your baseline (observed or modeled concentrations) and control (background concentrations) air quality surfaces, BenMAP will provide estimate of the total health impacts attributable to your pollutant of interest.
In either the monitor or modeled case, the result is a comparison of current conditions to an ideal scenario that controls virtually all anthropogenically caused air pollution; as a result the air quality delta and the resulting health effects associated with that delta represent an estimate of the total health burden associated with current levels of your selected air pollutant in your study area.