The loss of catalyst fines appears to be a function of air input rate and cyclone design. Enriching air with oxygen, thus reducing the gas amount, would be considered a step in the right direction, however it's not always considered economically attractive.
To reduce losses from regenerators, new solid recovery system ideas are been investigated, among them combinations of gravitational settling (Stokes' Law), centrifugal (cyclones), and electrostatic forces (ESP), for new designs and retrofits.

If you want to check losses or catalysts performance in an FCC Unit, you have to study and understand the analysis of equilibrium catalysts, either physical analysis or chemicals analysis. That is to say, your inquire is better to analyze it by Particle Size Distribution (PSD) and Apparent Bulk Density (ABD), that they are physical analysis among others. If PSD and ABD are higher than previous analysis, then, there are less fines catalysts in the vessels and therefore losses could have increased. That situation could be by catalyst attrition inside the reactors, cyclones efficiency, among others causes. An efficient cyclone recovers between 4 and 10 % of particles lesser than 40 µ.  
In an FCC Unit that it is working properly, losses could be lesser than 0.6 ton/day.

Sorry my last message. If ABD is lesser than previous analysis,then, there are less fines catalysts in the vessels and therefore losses could have increased. This analysis is a good method to assess the catalyst performance in the cyclones, in reference to the catalyst recuperation.

these other guys have told you a lot but not really answered your question.
stack releases would not be recorded on a release/year period because none of the refiners would admit to having regular releases or having an average loss..they are a sign of bad things  going on the the Regen. if they happen suddenly or poor cyclone/regen bed or  burning  efficiency if they are going on all the time,  cracking in the cyclone/plenum chamber etc stack emissions are generally kept as low as possible as  they are a loss of inventory ie $ also too great a plume might result in an EPA fine...more $