ES&H Manual



6670 Thermal Stress



1.0             Purpose


Jefferson Lab defines thermal stress as the physical and physiological reactions of a worker to temperatures that fall outside the normal comfort zone. The potential for thermal stress at Jefferson Lab exists mainly during the summer and winter months.


Mitigation actions are used to reduce thermal stress hazard conditions. The actions defined within this section meet or exceed the contractual requirements of 10 CFR 851.


2.0             Scope


Jefferson Lab recognizes that the most effective mitigation technique for thermal stress conditions is to wear appropriate clothing, and personal protective equipment. Work planning at Jefferson Lab, particularly during the summer months, considers ambient temperature and implements mitigation techniques as required. 


Jefferson Lab uses the National Weather Service Heat Stress Index for areas exposed to ambient conditions. For temperature monitoring, application guidelines, and calculations, the 2016 Threshold Limit Values for Physical Agents in the Work Environment section on Thermal Stress – Heat Stress & Heat Strain is used (measured as the Wet Bulb Globe Temperature (WBGT)).


This chapter does not address specific hazards or injuries resulting from sudden exposure to cryogenic materials. See ES&H Manual Chapter 6550 Cryogenic Safety Program.


3.0             Responsibilities

NOTE:  Management authority may be delegated to a task qualified Jefferson Lab employee at the discretion of the responsible manager.


3.1              Everyone at Jefferson Lab

·         Maintain fluid (especially water) intake.

·         Immediately report heat stress symptoms to supervisor and Occupational Medicine.

·         Follow work demand restrictions or work/rest regimens when indicated by ESH&Q Division.

·         Obtain heat stress training as required in SRL.

·         Be aware of adverse temperature conditions. Take appropriate precautions as outlined in ES&H Manual Chapter 6670 Appendix T1 Heat Stress Mitigation and ES&H Manual Chapter 6670 Appendix T2 Cold Stress Work Cessation Procedure.


3.2              Industrial Hygiene

·         Monitor anticipated heat conditions and conduct heat stress monitoring

·         Advise staff when work demand and work/rest regimen is to be implemented.

·         Maintain heat and cold monitoring records in accordance with department procedures.


3.3              Facilities Management and Logistics

·         Maintain the on-site Jefferson Lab weather station and provide a link to the data on a Jefferson Lab web page (currently https://www.jlab.org/fm/wx/).


3.4              Supervisor/Subcontracting Officer’s Technical Representative (SOTRs)/Sponsor

·         Request assistance from Industrial Hygiene to evaluate work assignments involving heat stress conditions.

·         Minimize worker’s exposure to heat sources when feasible.

o   Allow for acclimatization in work plan when elimination of heat stress conditions is not feasible.

·         Provide appropriate rest periods for workers. Consult Industrial Hygiene for appropriate work/rest schedules.


3.4.1        SOTRs also

o   Ensure subcontractor personnel abide by their Jefferson Lab accepted procedure or this procedure’s requirements.

o   Inform subcontracted workers of thermal stress warnings and notifications.

o   Ensure subcontracted workers are properly advised of work modification and rest periods.

o   Ensure fluid replacement sources and shelter techniques are available.

o   Notify ESH&Q of thermal stress areas that may require monitoring.

o   Review and accept subcontractor’s thermal stress program which must meet or exceed the requirements of this Jefferson Lab program


o   The subcontractor follows this program and the procedures outlined in its associated appendices:

§  ES&H Manual Chapter 6670 Appendix T1 Heat Stress Mitigation

§  ES&H Manual Chapter 6670 Appendix T2 Cold Stress Work Cessation Procedure


4.0             Expectations


4.1              Heat Conditions

Areas of known routine hot working environments for all or part of the year are monitored on a periodic basis. ES&H Manual Chapter 6670 Appendix T1 Heat Stress Mitigation addresses the procedure used to monitor and mitigate potential injury or illness due to heat stress.


4.2              Cold Conditions

As of the approval date of this chapter, there are no known work environments with temperatures that would be considered cold stress areas. One area with routine cold conditions is the food refrigeration area of CEBAF Center. However, this area is not occupied for continuous work but only visited as needed. ES&H Manual Chapter 6670 Appendix T2 Cold Stress Work Cessation Procedure addresses the procedure used to mitigate potential injury or illness due to cold stress.


5.0             References


·         EHS&Q Manual 2410 Appendix T1 Hazard Issues List

·         Facilities Management & Logistics Live Weather available from the Jefferson Lab Insight Webpage

·         2016 ACGIH Threshold Limit Values for Physical Agents in the Work Environment, section on Thermal Stress


6.0             Revision Summary


Revision 2.0 – 05/29/19 – ‘Heat and Cold Stress Mitigation Program’ retitled ‘Thermal Stress’ to reflect current lab operations; clarified responsibilities 

Revision 1.4 – 06/19/18 – Updated TPOC to J.Williams

Revision 1.3 – 06/04/15 – Periodic Review; updated Industrial Hygiene responsibilities

Revision 1.2 – 09/27/12 – Periodic review; no changes required

Revision 1.1 – 05/10/11 – Updated to provide for “hot work” activities

Revision 1.0 – 05/09/09 – Updated to reflect current laboratory operations










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ESH&Q Division

Jennifer Williams





This document is controlled as an on line file.  It may be printed but the print copy is not a controlled document.  It is the user’s responsibility to ensure that the document is the same revision as the current on line file.  This copy was printed on 6/19/2019.