The article in question talks about contaminants settling onto compressor blades, so the deposits of sulphuric acid droplets make sense.
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Sulfuric acid mist is formed from releases of sulfur trioxide or oleum, a mixture of sulfuric acid and sulfur trioxide. On release these react with water in the atmosphere and form a dense cloud of mist. The mist is likely to contain submicron droplets that remain airborne until they absorb additional water and rain out or are deposited onto surfaces. In an accident, the size of the droplets inhaled can be expected to exceed that on release and the authors assume a droplet size of 1 µm. As it happens, this is the size for which most of the data are available
https://www.sciencedirect.com/topics/engineering/acid-mist