Efectos del calor

HeaHletahlth Hazazrdasrds

Heat Stress
Understanding factors and measures helps
SH&E professionals take a proactive management approach
By Stephanie Helgerman McKinnon and Regina L. Utley

HEAT STRAIN and the effects of heat stress are the subject of many news reports and even some nation- al headlines (e.g., Macon Telegraph,USA Today). In
2002, Bureau of Labor Statistics (BLS) reported 40 fatalities resulting from exposure to environmental heat. Forty percent of those deaths occurred in the construction industry, 25 percent in agriculture forestry and mining, 10 percent in transportation and public utilities, and 7.5 percent in manufactur- ing. A BLS report with summary statistics shows double-digit fatalitiesfrom exposure to environmen- tal heat in each year from 1992 to 2001: 1992 = 12;
1993 = 22; 1994 = 28; 1995 = 35; 1996 = 18; 1997 = 22;
1998 = 34; 1999 = 35; 2000 = 21; and 2001 = 24. Based
on what is known about heat strain and illness as a
result of heat stress, one can argue that all of these
reported cases were preventable.
In 29 CFR 1910.132,Personal Protective Equipment
(PPE), OSHA requires employers to assess workplace
hazards that require use of PPE. If hazards are present,
3) understanding and using evaluation tools
(including measurement instruments).
Recognition & Training
Early recognition is key since heat-related disor- ders generally occur in progression. Early recogni- tion of symptoms and interventionwill prevent progression to a more medically serious phase. Understanding the body’s physiological response to reduce the increased heat load is useful when dis- cussing this progression. The primary cooling actions that occur include increased heart rate to move blood and heat to the skin, and increased sweating. These actions prevent a rise in the core body temperature. The hypothalamus worksto keep core body temper- ature at 37ºC ±1. Normal body temperature taken rectally is 37.6ºC (99.6ºF) or 37ºC (98.6ºF) taken orally. Efforts to control heat-related conditions attempt to prevent a rise in core body temperature above 38ºC (100.4ºF)—or less than 1ºC. American
employers must select PPE that will protect employ- ees. Paragraph (c) requires that the PPE be of safe design andconstruction for the work to be performed. Paragraph (f)(1)(iv) requires training to address the PPE’s limitations. Certain types of PPE are offered as protection when heat stress is an identified hazard, while use of certain types of PPE may increase the potential for heat strain. Some PPE selected as a con- trol may also present a limitation. For example, some early models of cooling vests wereheavy and may have contributed to cardiovascular strain.
Several tools are available to help manage and prevent heat strain. The first part of this article focus- es on the identification of readily available tools that are inexpensive, easy to understand and easy to use. The second part of the article identifies PPE avail- able to help prevent heat strain; PPE that meets therequirements of 29 CFR 1910.132 Paragraph (c); and PPE that can complicate management of heat-relat- ed conditions [Paragraph (f) limitations].

Proactive Management
Three broad areas should be considered when establishing a proactive management program:
1) training and (early) recognition;
2) management of personal factors;
Conference of Governmental IndustrialHygienists (ACGIH) recommends a peak
of 38.5ºC (101.1ºF) to allow for a margin of
safety [ACGIH(a)].
When providing training on heat-relat-
ed disorders and heat-stress management,
the philosophy is no different than it is for
other safety training: The trainer should
provide the information most useful to the
audience. For example, workers should
understand how to recognize signs and...