Dr. Kenneth W. Smith to Dr. T. R. Grainger on Measuring Blood Oxygen to Detect Asbestosis Early (1954)

A one-page letter of October 15, 1954, from Dr. Kenneth W. Smith, Johns-Manville's medical director, to Dr. T. R. Grainger, the company physician at Asbestos, Quebec, sending a booklet on an instrument for measuring oxygen saturation in the blood that Dr. Schepers had found successful. Smith thought the method too complicated for the plant medical program, but recalled that he, George Wright and Paul Cartier had tried to develop a simple test, because "the oxygen saturation falls in asbestotics before there is definite X-ray evidence of the disease." He wrote that it would help to have a method showing "that an employee had had sufficient dust exposure before he has suffered any great harm."

In Johns-Manville's chronology

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

Dr. Kenneth W. Smith writes to Dr. T.R. Grainger (Asbestos), 10/15/54, about the use of a cyclops in determining the oxygen saturation in the blood. Dr. Smith states that although the method seems a little complicated to use in the plant medical program, he thought Dr. Grainger should know about it. Dr. Smith would like a simple method to be developed for determining oxygen saturation, because he believes it would be a good tool in the prevention of asbestosis (oxygen saturation falls in asbestotics before there is definite X-ray evidence of the disease). "I think it would be a great help if we could develop some simple method which would indicate to us that an employee had sufficient dust exposure before he has suffered any great harm."