Our analyses generally do not combine PM generated from engine combustion with that from tirewear and brakewear because they have different properties. However, if you need to combine tirewear, brakewear and exhaust PM, it is appropriate to divide the mass of the sum of all of the PM emissions (grams) from all of the processes (including brake wear and tire wear) by the vehicle miles traveled (VMT) reported for the running emission process to generate rates of grams per mile.
When PM emissions are reported by process and “distance travelled” is reported in the “movesactivityoutput” table, why is “distance travelled” not reported by PM process?
Both brake wear and tire wear are based on the same vehicle activity data that is used to calculate running emissions. Repeating the VMT used (for each process) in the database would be redundant and could lead to errors when computing total VMT.
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