in simple terms, let's say I inject particles as soon as it enters the filter domain 50% gets deposited in the first cell and 25% gets deposited in the cell inside it and 12.5% in the next cell and 6.25% of particle mass in next cell inside and the remaining 6.25% of mass just gets penetrated and goes out. (To have a simplified view for understanding purposes, i am hypothetically describing it in extremely simple terms)

Let us assume this happens across the volume.

Once i finish deposition i compute the volume integral of the sum of the total mass in filter domain. So do i need to parallelize this scalar update?