New Jersey Department of Health to J. E. Begert on Dust in the Manville Textile Department (1944)

A two-page letter of November 17, 1944, from Dr. J. Lynn Mahaffey, New Jersey's Director of Health, to J. E. Begert, manager of Johns-Manville's Manville, New Jersey, plant, after the state Bureau of Industrial Health sampled dust in the plant's textile department. The letter notes that the accepted limit of "five million particles per cubic foot" made "no allowance for fibre count which more recent studies have indicated may be of primary importance." It recommends dust control for dry brake lining weaving, better use of exhaust equipment in cloth weaving, more care in fiber break-up, and further sampling at the mule spinning machines.

What it shows

The state found that bin unloading and weighing was "above the allowable limit," but judged that "the continual use of respirators by these operators gives adequate protection." In cloth weaving, operators had to be taught to use their exhaust equipment correctly or dust "will build up above the maximum allowable concentration." The letter shows that in 1944 government inspectors had told J-M directly that parts of its main textile operation needed better dust control, and that counting fibers, not just total dust, might matter most. See Threshold Limit Value (TLV).

In Johns-Manville's chronology

Johns-Manville's own chronology of what the company knew describes this document as follows:

State of NJ inspection of Manville Textile Department, 11/17/44, notes certain stations above TLV and recommends improvements.