ES&H Manual



6670 Appendix T1

Heat Stress Work Cessation Procedure



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 to be used to reduce injuries or illnesses caused by heat stress. It outlines worker action steps and Jefferson Lab’s site-wide alert and notification procedures which are implemented when the National Weather Service Heat Index temperatures reach 80oF.


Subcontractors follow this procedure or their own Jefferson Lab approved procedure.


The process steps for this procedure are performed in coordination with ES&H Manual Chapter 6670 Heat and Cold Stress Mitigation Program.


3.0            Responsibilities

NOTE:           Management authority may be delegated at the discretion of the responsible manager. 


3.1              Everyone at Jefferson Lab

·         Maintain fluid (especially water) intake.

·         Wear appropriate work clothes and PPE appropriate for work activities assigned.

·         Immediately report heat stress symptoms[1] to supervisor and Occupational Medicine.

·         Curtail activities, including voluntary athletic programs, at Stage 2 or higher conditions.


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

·         Request assistance, when required, from Industrial Hygiene to evaluate work assignments involving heat-stress conditions. This specialized monitoring uses calibrated instrumentation to determine the wet bulb globe temperature and decisions based on the 2005 Threshold Limit Values for Physical Agents in the Work Environment’.

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

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

·         Provide heat and cold stress hazard awareness training (see ES&H Manual Chapter 4100 Communicating Safety Requirements) to workers.  (Guidance/talking points may be requested from Industrial Hygiene or Occupational Medicine.)

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


3.2.1        Subcontracting Officer’s Technical Representatives (SOTRs) also

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


4.0            Process Steps


NOTE: “Site-wide heat index notifications” are provided only when outside temperatures reach indicated heat index levels. The Heat Index is used as a screening method and is available through the JLab Weather Station and National Weather Services. The JLab Weather Station/System also provides electronic notification. Workers performing activities involving heat (i.e. hot work) are to perform their responsibilities when heat index levels are reached in their area as if notification had been received.


4.1              Heat Index Criteria Stages:


Stage 1:           Heat Index 85 - 92oF


Step 1:             Facilities Management: Based on conditions at Jefferson Lab (http://www.jlab.org/fm/wx/) – initiate notification of heat stress conditions.


Step 2:             ESH&Q Professionals/Supervisors/SOTRs: Upon receipt of heat stress condition notification:

·         Inform workers of heat stress warning.

·         Familiarize workers with heat stress, its symptoms1, and prevention.

·         Confirm provisions for fluid replacement and shelter procedures as appropriate.


Step 3:             Workers:

·         Drink ample amounts of water – more than your sense of thirst indicates.

·         Wear light-colored, loose-fitting clothing.  Select fabrics known to wick moisture away from the skin.

·         Recognize personal risk factors.  If at higher risk than normal, advise your supervisor and Occupational Medicine, and limit work activities.  If taking medication, be familiar with any potential risks.

·         Stop activity at first signs of heat illness1.  Seek a cooler area and rest.  Recline if possible.


Stage 2:           Heat Index 93 – 103oF

In addition to Stage 1 Activities, perform the following:


Step 1:             Facilities Management: Notify ESH&Q Professionals/ Supervisors/SOTRs of additional notification or changes.


Step 2:             ESH&Q Professionals/Supervisors/SOTRs: Upon receipt of Stage 2 notification:

·         Inform workers of second heat stress notification.

·         Plan and schedule work to minimize worker exposure.

o   Organize the day’s activities to perform the most strenuous work in the cooler hours of the day.

o   Allow for increased rest breaks.

o   Make allowances for personal protective clothing and equipment that retains heat and restricts the evaporation of sweat.


Step 3:             Workers:

·         Self-monitor hydration:

o   Before activity drink water.

o   During activity increase water intake.  Do not wait until you are thirsty.

o   Avoid caffeine and other potentially dehydrating beverages.

·         Be alert to indications of heat stress in fellow workers.

·         Inform your supervisor and go to Occupational Medicine if you feel ill.

·         Curtail voluntary athletic activities.


Stage 3:           Heat Index 104 - 115oF

In addition to Stages 1 and 2 Activities, perform the following:


Step 1:             Workers:

·         Contact Industrial Hygiene for guidance regarding work/rest regimen.

·         Limit strenuous activities.

·         Utilize cooling systems and locations for rest breaks (fans, air-conditioned spaces, mist systems, etc.).

·         Utilize shade for work activities where feasible.

·         Be alert to early warning signs of over-heating.

·         Increase fluid intake to amount sufficient for normal urine production.

·         Wrap cool, wet towel or bandana around neck.  Wring it out and re-soak it when it no longer feels cool.

·         Remove your hard hat whenever you are out of the mandatory PPE area.


Stage 4:           Heat Index >116oF


Step 1:             Facilities Management: Alert ESH&Q Professionals/Supervisors/ SOTRs.


Step 2:             ESH&Q Professionals/Supervisors/SOTRs: Upon receipt of warning notification:

·         Cease all work within the heat hazard areas unless approved by the Cognizant Division Manager.


Work Planning & Mitigation for Heat Stress Conditions

Forecasted or Observed Conditions


JLab Action(s)

Heat Index

≤ 80°F

Tolerable for acclimatized, healthy worker.



Heat Index

80 – 92°F


Discomfort range for most people.

Unusual onset or severity of fatigue possible.

Supervisors alert those affected

When Heat Index is reached: Implement Stage 1 Process Steps

Site-wide Notification

Heat Index

93 – 103°F


Muscle Cramps and/or Heat Exhaustion possible

Heat Stroke possible for at-risk workers

Supervisors alert those affected.

When Heat Index is reached:

Implement Stage 2 Process Steps.

Site-wide Notification

(Authorization to limit work activity is possible)

Heat Index

104 – 115°F


Muscle Cramps, and/or Heat Exhaustion likely

Heat Stroke probable for at-risk workers

Supervisors alert those affected

When Heat Index is reached:

Implement Stage 3 Process Steps.

Site-wide Notification

(Authorization to limit work activities is certain.)

Heat Index

≥ 116°F


Extreme Danger of heat stroke

Supervisors alert those affected

When Heat Index is reached:

Implement Stage 4 Process Steps.

Site-wide Notification

(Authorization to cease all work unless approved by the Cognizant Division Manager.)


5.0            Revision Summary


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











ESH&Q Division

Richard Owen





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 6/4/2015.

[1] Heat Stress Symptoms include: headache, dizziness, lightheadedness or fainting; weakness and moist skin; mood changes such as irritability or confusion; upset stomach or vomiting.