Only the furnace loaders had time weighted average exposures to a-quartz that frequently exceeded the permissible level allowed by the Province of Quebec, 100 µg/m3; 50% of their a-quartz exposures were greater than 100 µg/m3. Only four samples were collected, however, so the level of exposure was not well defined. The mixers, payloader operators, old mix operators, and carboselectors had geometric mean exposures to a-quartz that were
about half of the 100 ug/m3 limit. The remainder of the job categories exposures were well below the permissible limit.

Речь идет об исследовании степени воздействия вредных веществ, выделяемых в процессе производства карбида кремния, на рабочих завода. Есть ли такая профессия - карбоселектор, - или она по-русски звучит по-другому, кто в курсе?

http://www.worklib.ru/laws/ussr/10009697.php