Annual Report of the Surgeon General of the U.S. Public Health Service on Dust Standards (1930)

Two pages from the Annual Report of the Surgeon General of the U.S. Public Health Service for the fiscal year 1930: the title page and page 49, from the section on industrial hygiene. Reporting on its study of workers in dusty trades, the Public Health Service says it was able to set "a tentative standard of dustiness for granite-cutting plants below which there seemed no indication that any serious health hazard would result," placed "somewhere between 10,000,000 and 20,000,000 particles" per cubic foot of air.

What it shows

This is an early government attempt to fix a "safe" dust level, the idea that later became the Threshold Limit Value (TLV). The standard on these pages is for granite dust, which contains free silica; the pages do not mention asbestos or Metropolitan Life.

In Johns-Manville's chronology

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

Metropolitan proposes tentative safe exposure standard of 9-20 mppcf. USPHS suggests 10 mppcf.

Editor's note: J-M's description says Metropolitan Life proposed a standard of 9 to 20 million particles per cubic foot and the Public Health Service suggested 10. These pages give only the Public Health Service figure of 10 to 20 million, for granite-cutting plants; they say nothing about Metropolitan Life or asbestos.