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Slide 13


    Title: PEL - General Industry

    • Quartz (respirable dust):
      10 mg/m3
      % respirable quartz + 2

    • Cristobalite and Tridymite: use ½ of the value calculated from the formula for quartz
    [Includes illustration of a man and the OSHA logo]

    Speaker Notes:

     What is an overexposure in General Industry?

    OSHA’s Permissible Exposure Limit (PEL) for General Industry was adopted in 1971 (from 1968 ACGIH TLVs) and represents the maximum amount of respirable dust containing crystalline silica (as quartz) that is permitted in the work environment. The standard is codified at 29 CFR 1910.1000.

    As shown by this formula the PEL, expressed as milligrams of respirable dust in a cubic meter of air, decreases as the percentage of the dust that is crystalline silica increases.

    In other words, the more crystalline silica there is in the dust, the less dust you are allowed to breathe into your lungs!

    Sample results are obtained by a gravimetric method.