ES&H Manual



6670 Appendix T1

Heat Stress Mitigation



1.0             Purpose


Areas known as routine hot working environments for all or part of the year are monitored on a periodic basis. This appendix addresses the procedure used to monitor and mitigate potential injury or illness due to heat stress.


2.0             Scope


This appendix provides mitigation steps used to reduce injuries or illnesses caused by heat stress through proper planning and work execution. The approach is to:

·         Proactively monitor the heat stress conditions using heat index as a predictor.

·         Educate supervisors and workers how to best prepare to perform in hot conditions.

·         Plan work and modify those plans as necessary, so that the combination of work activities and heat index do not place workers in a hazardous situation.

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.

·         Wear appropriate work clothes and apply other relevant mitigation measures when hot weather is anticipated.

·         Monitor yourself and your colleagues for heat stress symptoms report any symptoms to supervisor and Occupational Medicine.

·         Curtail activities, including voluntary athletic programs, at Stage 2 or higher conditions if symptoms are noted or directed to do so.


3.2              Industrial Hygiene

·         Monitor anticipated heat conditions and prefer heat stress monitoring.

·         Notify supervisors/SOTRs when heat conditions indicate that heat stress hazards are anticipated.

·         Notify supervisors/SOTRs when heat conditions require a work/rest regimen or change in work demand.

·         Notify all staff when heat conditions require a suspend work.

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

·         Monitor anticipated weather conditions and plan accordingly.

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

·         Subcontracting Officer’s Technical Representatives (SOTRs) also

·         Ensure subcontractor personnel abide by their accepted program or Jefferson Lab’s program requirements.


4.0             Process Steps


4.1              Monitor the Weather

Typically, Jefferson Lab encounters conditions that could lead to heat stress between May and September every year. During this period, all staff should monitor local weather predictions [http://www.weather.gov/bgm/heatindexforecasts] to plan accordingly.


When heat conditions are anticipated to potentially cause a heat stress hazard, EHS&Q division will send a series of notifications to all staff. The notification sequence is summarized in Table 1 below. To sign up for notifications, contact the Industrial Hygiene Group at x7882 or x6380.


Table 1. Heat Index based notification sequence

When notification is sent

Heat Index prompting notification

Supervisor/SOTR action

Day before high heat conditions


(projected heat index)

Plan the next day or week’s work to reduce heat stress

Day of high heat conditions

89°F, 94°F, & 105°F

Reduce the work demand and/or implement work/rest regimen as indicated in ES&H Division notification. See Figure 1.

Day of high heat conditions


Return to light work with reduced 50/50 work-rest regimen until heat index is below 94°F.

Day of high heat conditions


SUSPEND all outdoor work and work in un-conditioned spaces.

4.2              Protect Yourself

Personal mitigation measures must be taken if the heat index is projected to be at least 89°F; including:

·         Wear loose fitting, light colored clothing. Select fabrics known to wick (absorb or drain) moisture away from the skin.

·         Increase normal water intake prior to work and continue water intake; do not wait until you are thirsty.

·         Avoid caffeine.

·         Talk to Occupational Medicine if any medication you are taking might affect your ability to work in hot environments.

·         Familiarize and monitor yourself and your co-workers for signs of heat stress.  Examples of symptoms provided in Section 4.6.


4.3              Protect Your Team When Planning

Hazard mitigation measures must be built into work plans if the heat index is projected to be at least 89°F.

When planning work, it is necessary to consider an activities work demand. Work demand is broken down into light, moderate, and heavy categories. Table 2 provides examples of activities within these categories. 

Table 2. Work Demand Categories




·   Sitting with light manual work with hands/arms and driving.

·   Standing with light arm work and occasional walking.


·   Sustained manual work with hands, arms, legs.

·   Light pushing and pulling.

·   Normal walking.


·   Intense arm and trunk work – carrying, shoveling, manual sawing.

·   Pushing and pulling heavy loads.

·   Walking at a fast pace.


4.4              Modify Activities When Conditions Change

Action must be taken when the heat index reaches levels indicated for each specific work demand. When conducting work outdoors or indoor areas without cooling (i.e. compressor rooms and refrigeration machinery areas), follow guidance in Table 3. Figure 1 provides a graphic representation of work demand and work/rest regimen changes when the high index increases.  


Table 3. Required Action for Hazardous Heat Conditions

Work Demand

Heat Index

Required Action



Reduce the work demand by reducing activity work demand or start a 50/50 work rest regimen.






Figure 1. Process for work demand and work/rest regimen changes as high index increases.



4.5              Suspend Work

Suspending work at all outdoor locations and indoor areas without cooling is required when notified or when the heat index exceeds temperatures listed in Table 4. Work can only be resumed by one of the following:   

·         Permission is obtained from the appropriate Division Manager.

·         Local conditions WBGT is measured by Industrial Hygiene, indicates that a work/rest regimen can continue based on local temperature conditions.

·         The head index reduces (temperature drops) below levels in Table 4. 


Table 4. Suspend work, Extremely Hazardous Heat Conditions

Work Demand

Heat Index







4.6              Recognize Heat Stress Symptoms

Anyone working in an environment with potential to cause heat stress need to be able to recognize related symptoms; including:   

·         Headache

·         Dizziness

·         Lightheadedness or fainting

·         Weakness

·         Mood changes such as irritability or confusion

·         Upset stomach or vomiting

·         Pale skin


Stop activities at first signs of heat stress; move the affected person to a cooler, shaded area and immediately notify the supervisor/SOTR and Occupational Medicine.


5.0             References

·         Jefferson Lab Tech Note JLAB-TN-19-008 “Heat Stress Program Update: Validation for Using Heat Index as an Alternate to the 2016 WBGT”

·         Jefferson Lab Tech NOTE JLAB-TN-15-044 “Validation for using Heat Index as an alternate to the Wet Bulb Globe Temperature at JLab”


6.0             Revision Summary


Revision 2.0 – 05/29/19 – ‘Heat Stress Work Cessation Procedure’ retitled ‘Heat Stress Mitigation’ to reflect current laboratory operations; added IH responsibilities; updated Process Steps

Revision 1.6 – 06/19/18 – Updated TPOC from B.Manzlak to J.Williams

Revision 1.5 – 04/24/18 – Removed outdated TLV reference per CATS#STR-2017-12-01-03

Revision 1.4 – 03/15/16 – Updated TPOC from R.Owen to B.Manzlak

Revision 1.3 – 06/04/15 – Periodic Review; Updated 3.0 Responsibilities for Supervisor/SOTRs/Sponsor and updated note box under 4.0; Corrected revision summary sequence  

Revision 1.2 – 09/27/12 – Periodic Review; no changes to content required

Revision 1.1 – 05/09/11 – Updated to provide for “hot work” activities

Revision 1.0 – 11/19/09 – Updated to reflect current laboratory operations











ES&H 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.