Document xa1320aGbpnJwKmYbrrekvN1

TABLE 37-G THRESHOLD LIMIT VALUES FOR PHYSICAL AGENTS 1973 Copyright 1973 by American Conference of Governmental Industrial Hygienists Reprinted with permission PREFACE PHYSICAL AGENTS These threshold limit values refer to levels of physical agents and represent con ditions under which it is believed that nearly all workers may be repeatedly ex posed day after day without adverse ef fect Because of wide variations in in dividual susceptibility, exposure of an oc casional individual, at, or even below, the threshold limit may not prevent an noyance, aggravation of a pre-existing con dition, or physiological damage These threshold limits are based on the best available information from industrial experience, from experimental human and animal studies, and when possible, from a combination of the three These limits are intended for use in the practice of industrial hygiene and should be interpreted and applied only by a per son trained in this discipline They are not intended for use, or for modification for use, (1) in the evaluation or control of the levels of physical agents in the com munity, (2) as proof or disproof of an existing physical disability, or (3) for adoption by countries whose working con ditions differ from those in the United States of America These values are reviewed annually by the Committee on Threshold Limits for Physical Agents for revisions or additions, as further information becomes available Notice of Intent. At the beginning of each year, proposed actions of the Com mittee for the forthcoming year are issued in the form of a "Notice of Intent '' This notice provides not only an opportunity for comment, but solicits suggestions of phys ical agents to be added to the list The suggestions should be accompanied by substantiating evidence As legislative code. The Conference recognizes that the Threshold Limit Values may be adopted in legislative codes and regulations If so used, the intent of the concepts contained in the Preface should be maintained and provisions should be made to keep the list current NOTICE OF INTENT TO ESTABLISH THRESHOLD LIMIT VALUES Heat Stress These Threshold Limit Values refer to heat stress conditions under which it is be lieved that nearly all workers may be re peatedly exposed without adverse health effects The TLVs shown m Table 1 are based on the assumption that nearly all acclimatized, fully clothed workers with adequate water and salt intake should be able to function effectively under the given working conditions without exceeding a deep body temperature of 38 C (WHO technical report senes #412, 1969 Health Factors Involved tn Working Under Con ditions of Heat Stress) Since measurement of deep body tem perature is impractical for momtonng the workers' heat load, the measurement of environmental factors is required which most nearly correlate with deep body tem perature and other physiological responses to heat At the present fame, Wet BulbGlobe Temperature Index (WBGT) is the simplest and most suitable technique to measure the environmental factors WBGT values are calculated by the fol lowing equations 1 Outdoors with solar load. WBGT = 0 7WB + 0 2GT + 0 1DB 2 Indoors or Outdoors with no solar load WBGT -- 0 7WB + 0 3GT where WBGT -- Wet Bulb-Globe Tempera ture Index WB = Natural Wet-Bulb Tempera ture DB = Dry-Bulb Temperature GT = Globe Thermometer Temper ature 1095