**5. Conclusions**

Seven service-aged 13.2 kV ceramic insulators, located in the surroundings of a Canadian aluminum plant, were collected for a post-pollution severity assessment. Various characteristics, such as ESDD, NSDD, and the leakage current, were investigated to assess the pollution level of the insulators. From these investigations, the main conclusions can be summarized as follows:


**Author Contributions:** This work was p under the supervision of I.F., who designed this research and gave the whole guidance. E.H., F.M. and K.M.L.Y. performed the experimental investigations. J.S.N. and A.B. collected all the data, carried out calculations, result display and analysis and wrote the manuscript. The final draft of paper was thoroughly reviewed by I.F. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research was funded by Natural Science and Engineering Research Council (NSERC) gran<sup>t</sup> number 513476-17.

**Acknowledgments:** The authors gratefully acknowledge the cooperation of Rio Tinto, Saguenay branch in Canada, for allowing the investigations and authorizing the publication of this manuscript.

**Conflicts of Interest:** The authors declare no conflict of interest.
