BY ORDER OF THE SECRETARY OF THE AIR FORCE

BY ORDER OF THE

SECRETARY OF THE AIR FORCE

DEPARTMENT OF THE AIR FORCE

INSTRUCTION 48-151

2 MAY 2022

Aerospace Medicine

THERMAL STRESS PROGRAM

COMPLIANCE WITH THIS PUBLICATION IS MANDATORY

ACCESSIBILITY: Publications and forms are available on the e-Publishing website at

www.e-Publishing.af.mil for downloading or ordering.

RELEASABILITY: There are no releasability restrictions on this publication.

OPR: AFMRA/SG3PB Certified by: USAF/SG3/4

(Maj Gen Sharon R. Bannister)

Supersedes: AFI48-151, 7 April 2016 Pages: 30

This Department of the Air Force Instruction (DAFI) implements Air Force Policy Directive

(AFPD) 48-1, Aerospace & Operational Medicine Enterprise (AOME), and provides supporting

guidance for establishing and implementing an effective local Thermal Stress Program to

commanders, supervisors, medical personnel, and individuals at every level. This DAFI covers

thermal stress education, environmental monitoring, and guidance charts. Signs and symptoms of

thermal illness are provided in section 23.10 of Air Force Tactics, Techniques, and Procedures

(AFTTP) 3-4, Airman’s Manual.. This publication applies to the entire Department of Air Force

(DAF), including all civilian employees and uniformed members of the Regular Air Force, the Air

Force Reserve, the Air National Guard, and the United State Space Force. This instruction does

not apply to DAF units receiving thermal stress guidance from other military services under joint

basing agreements. The lead service under the joint basing agreement will provide thermal stress

support in accordance with their regulations and guidance. Ensure that all records generated as a

result of processes prescribed in this publication adhere to AFI 33-322, Records Management and

Information Governance Program, and are disposed of in accordance with the Air Force Records

Disposition Schedule which is located in the Air Force Records Information Management System.

Refer recommended changes and questions about this publication to the office of primary

responsibility (OPR), AFMRA/SG3PB, using the AF Form 847, Recommendation for Change of

Publication; route AF Forms 847 from the field through the appropriate chain of command. This

publication may be supplemented at any level, but all supplements must be routed to the OPR,

AFMRA/SG3PB for coordination prior to certification and approval. The authorities to waive

wing/Space Force equivalent/unit level requirements in this publication are identified with a Tier

("T-0, T-1, T-2, T-3") number following the compliance statement. See DAFI 33-360,

2  DAFI48-151  2 MAY 2022 
Publications and Forms Management, for a description of the authorities associated with the Tier 
numbers. Submit requests for waivers through the chain of command to the appropriate Tier waiver 
approval authority, or alternately, to the requestor’s commander for non-tiered compliance items. 
This instruction requires the collection and/or maintenance of information protected by the Privacy 
Act of 1974 authorized by 10 United States Code (USC) § 9013, Secretary of the Air Force. The 
applicable  System  of  Record  Notice  (SORN),  OPM/GOVT-1  (77  FR  79694)  is  available  at 
https://dpcld.defense.gov/Privacy/SORNs/.    The  use  of  the  name  or  mark  of  any  specific 
manufacturer,  commercial  product,  commodity,  or  service  in  this  publication  does  not  imply 
endorsement  by  the  Air  Force.  Compliance  with  the  attachment  to  this  publication  is  not 
mandatory. 
SUMMARY OF CHANGES 
This document has been substantially revised and must be completely reviewed.  Major changes 
include  updated  roles  and  responsibilities,  defined  action  levels,  approved  risk  assessment 
methods, updated options for determining Wet Bulb Globe Temperature (WBGT) values based 
upon historical readings or an approved model, an updated Fighter Index of Thermal Stress (FITS) 
chart using dew point and dry bulb temperature, and updated definitions.  Additionally, the term 
thermal injury was replaced with thermal illness to align with Title 29, Code of Federal Regulations 
(CFR) 1904.46 and Department of the Air Force Manual (DAFMAN) 91-224, Ground Safety 
Investigation and Hazard Reporting definitions.  Lastly, the title changed from the Thermal Injury 
Prevention Program to the Thermal Stress Program. 
 
Chapter 1—PROGRAM OVERVIEW    5 
1.1.  Purpose. ...............................................................................................................  5 
1.2.  General.................................................................................................................  5 
1.3.  Keywords. ............................................................................................................  5 
Chapter 2—ROLES AND RESPONSIBILITIES    6 
2.1.  Assistant Secretary of the Air Force for Energy, Installations, and Environment 
(SAF/IE). .............................................................................................................  6 
2.2.  Deputy Assistant Secretary of the Air Force for Environment, Safety, and 
Infrastructure (SAF/IEE). .....................................................................................  6 
2.3.  Air Force Surgeon General (AF/SG). ....................................................................  6 
2.4.  Air Force Medical Readiness Agency, Aerospace Medicine Policy & Operations 
Division (AFMRA/SG3P). ...................................................................................  6 
2.5.  Major Command Surgeon General (MAJCOM/SG). .............................................  7 
2.6.  Installation Commander........................................................................................  7 
2.7.  Installation Environment, Safety and Occupational Health Council. ......................  7 
2.8.  Medical Unit Commander. ...................................................................................  7 
2.9.  Chief of Aerospace Medicine (SGP) or local equivalent. .......................................  8 

DAFI48-151  2 MAY 2022  3 
2.10.  Bioenvironmental Engineering Flight Commander or local equivalent. .................  8 
2.11.  Public Health (PH) Flight Commander or local equivalent. ...................................  10 
2.12.  Geographically Separated Unit Commander or Delegate (Medical Aid Station). ...  10 
2.13.  Aerospace Physiology. .........................................................................................  11 
2.14.  USAFSAM...........................................................................................................  11 
2.15.  Local Weather Flight (WF) or Detachment (Det) Commander or Reach-back 
Weather Unit. .......................................................................................................  11 
2.16.  Base Civil Engineer (BCE). ..................................................................................  12 
2.17.  Installation/Unit Safety Office. .............................................................................  12 
2.18.  Fitness Assessment Cell Manager. ........................................................................  12 
2.19.  Mission Swimming Pool Managers. ......................................................................  12 
2.20.  Unit/Organizational Commander. .........................................................................  12 
2.21.  Workplace Supervisor. .........................................................................................  13 
2.22.  Worker. ................................................................................................................  13 
Chapter 3—HEAT STRESS PROGRAM ELEMENTS    15 
3.1.  Heat Illnesses. ......................................................................................................  15 
3.2.  Critical Elements of a Heat-Related Illness Prevention Program............................  15 
3.3.  Acclimatization Program. .....................................................................................  15 
3.4.  Training Program. ................................................................................................  15 
3.5.  Heat Alert Program. .............................................................................................  16 
3.6.  Medical Surveillance Program. .............................................................................  16 
3.7.  Special Surveillance Environmental Monitoring. ..................................................  16 
3.8.  Heat Stress Guidelines. .........................................................................................  17 
Table  3.1.  Work/Rest Times & Fluid Replacement Guide, Technical Bulletin 507 (US 
Army, 2003). ........................................................................................................  17 
Table  3.2.  Modifications to WBGT for Body Armor/MOPP Gear Based Upon Workload......  18 
Chapter 4—THERMAL STRESS FOR AIRMEN/GUARDIANS IN FORMAL TRAINING 
COURSES AND PHYSICAL TRAINING    19 
4.1.  Thermal Illness Prevention for Airmen/Guardians in Training. .............................  19 
4.2.  Unit Physical Training. .........................................................................................  19 
Figure  4.1.  WBGT Category Comparison Based Upon Heat Production Rate in Watts (W). ...  20 
Table  4.1.  Recommended Cold Weather Thermal Illness Prevention. ....................................  21 

4  DAFI48-151  2 MAY 2022 
Chapter 5—COLD STRESS PROGRAM ELEMENTS    22 
5.1.  Cold Illnesses. ......................................................................................................  22 
5.2.  Critical Elements of a Cold-Related Illness Prevention Program. ..........................  22 
Figure  5.1.  Wind Chill & Frostbite Time (National Weather Service, 2001)............................  22 
Table  5.1.  Preventive Measures to Reduce Frostbite Risk, Technical Bulletin 508 (US 
Army, 2005). ........................................................................................................  23 
Chapter 6—FIGHTER INDEX OF THERMAL STRESS (FITS)    24 
6.1.  FITS. ....................................................................................................................  24 
6.2.  Assessing FITS Reference Values.........................................................................  24 
6.3.  FITS Tables Using Dew Point and Dry Bulb Temperature. ...................................  24 
6.4.  FITS Actions. .......................................................................................................  24 
Table  6.1.  Fighter Index of Thermal Stress Chart (
o
F)............................................................  25 
Attachment 1—GLOSSARY OF REFERENCES AND SUPPORTING INFORMATION    27 
 

DAFI48-151 2 MAY 2022 5

Chapter 1

PROGRAM OVERVIEW

1.1. Purpose. This instruction establishes procedures and assigns responsibilities for executing

the DAF Thermal Stress Program to prevent and manage thermal illness and optimize the safety

and health of Department of Air Force (DAF) personnel.

1.2. General. This DAFI supports AFPD 48-1 and the requirement to optimize the safety and

health of DAF personnel in the performance of their duties in any circumstance or location. This

instruction is an aid in planning and safely executing industrial activities, mission operations, field

exercises, training, community events, and other installation functions affected by heat or cold

stress. Failure to comply with this instruction can have a significant impact on mission capability

through degraded human performance and potentially result in the prolonged or permanent

incapacitation or death of DAF military and civilian workers (Airmen and Guardians.)

1.3. Keywords. Thermal stress is the general term used for physiological stress experienced by

the human body as a result of exposure to hot and cold environments resulting with heat stress and

cold stress. Thermal stress may result in acute and chronic thermal illnesses. Thermal illnesses is

the general term used for both heat illnesses and cold illnesses. See Attachment 1, “Glossary of

References and Supporting Information”, for additional terms, definitions, and references.

6 DAFI48-151 2 MAY 2022

Chapter 2

ROLES AND RESPONSIBILITIES

2.1. Assistant Secretary of the Air Force for Energy, Installations, and Environment

(SAF/IE).

2.1.1. Provides oversight of all matters pertaining to the formulation, review and execution of

plans, policies, programs and budgets relative to the Air Force Thermal Stress Program.

2.1.2. Delegates DAF Thermal Stress Program responsibilities to the Deputy Assistant

Secretary of the Air Force for Environment, Safety and Infrastructure.

2.2. Deputy Assistant Secretary of the Air Force for Environment, Safety, and

Infrastructure (SAF/IEE). As delegated by the SAF/IE, provides policy, guidance, direction and

oversight of all matters pertaining to the formulation, review and execution of plans, policies,

programs and budgets relative to the DAF Thermal Stress Program. Oversees implementation of

the program.

2.3. Air Force Surgeon General (AF/SG).

2.3.1. Provides strategic direction and develops policy to execute the DAF Thermal Stress

Program.

2.3.2. Advocates for health risk assessment, surveillance and control requirements associated

with DAF Thermal Stress Program through the medical and Line of the Air Force Planning,

Programming, Budgeting and Execution System.

2.3.3. Reports the status of the DAF Thermal Stress Program on an as-requested basis to

SAF/IE through a formal Program Management Review.

2.4. Air Force Medical Readiness Agency, Aerospace Medicine Policy & Operations

Division (AFMRA/SG3P).

2.4.1. Assists AF/SG with developing policy to execute the DAF Thermal Stress Program.

2.4.2. Supports DAF Thermal Stress Program initiatives by validating requirements.

2.4.3. Plans, programs, and budgets for resources and provides oversight for execution of the

DAF Thermal Stress Program through the office of Manpower, Personnel, and Resources

(AF/SG1/8).

2.4.4. Develops and monitors DAF-level performance measures to assess DAF Thermal Stress

Program effectiveness. Identifies metrics requiring Defense Occupational and Environmental

Health Readiness System (DOEHRS) data quality report development to USAF School of

Aerospace Medicine (USAFSAM) to meet metrics reporting requirements.

2.4.5. Reviews heat and cold illness risk reduction opportunities and makes recommendations

to assist Line of the Air Force in executing effective resource prioritization.

2.4.6. Identifies and prioritizes DOEHRS technical and management issues related to heat and

cold illness to the Department of Defense Industrial Hygiene Working Group or SAF/IEE or

Office of the Under Secretary of Defense for Acquisition and Sustainment (OUSD (A&S)) for

modification or other appropriate actions.

DAFI48-151 2 MAY 2022 7

2.4.7. Establishes a Bioenvironmental Engineering equipment modernization and

standardization process and ensures consistent utilization with respect to thermal stress

equipment.

2.4.8. Approves predictive heat stress modeling tools for use by the career-field.

2.5. Major Command Surgeon General (MAJCOM/SG).

2.5.1. As needed, establishes DAF Thermal Stress Program medical support priorities and

supplements to this DAFI to execute MAJCOM mission requirements.

2.5.2. Assists in the Air Force Planning, Programming, Budgeting and Execution process by

identifying and advocating for any DAF Thermal Stress Program requirements.

2.5.3. Supports thermal hazard identification, control, mitigation, or elimination

considerations in the Air Force operational capability requirements development process.

2.5.4. Ensures DAF Thermal Stress Program management performance monitoring across all

bases within their command through the MAJCOM and installation Environment, Safety, and

Occupational Health Councils.

2.5.5. Disseminates information pertaining to policy and new or pending legislation within

MAJCOM as requested by AF/SG.

2.5.6. Coordinates with AFMRA/SG3P to identify and resolve DAF Thermal Stress Program

programmatic issues.

2.6. Installation Commander.

2.6.1. Provides a safe and healthy workplace and community environment for all DAF military

and civilian personnel in accordance with DoD and DAF Environment, Safety, and

Occupational Health requirements as established in AFPD 90-8, Environment, Safety &

Occupational Health Management and Risk Management. (T-0)

2.6.2. Implements and directs execution of the installation Thermal Stress Program through

the installation Environment, Safety, and Occupational Health Council in accordance with AFI

90-801, Environment, Safety, and Occupational Health Councils. (T-1)

2.6.3. Ensures required Thermal Stress Program hazard controls are implemented and

functioning correctly. (T- 3)

2.6.4. Ensures mechanisms for dissemination of thermal risk levels (flag codes) to assigned

personnel. (T-1) This can include postings to organizational web sites, use of the commander’s

access channel, colored flags, signage, or other channels tailored to the installation and

mission.

2.7. Installation Environment, Safety and Occupational Health Council. Provides senior

leadership input, direction and management review of the installation Thermal Stress Program in

accordance with AFI 90-801 and this DAFI. (T-1)

2.8. Medical Unit Commander. For Reg AF medical units, this is the Medical Treatment

Facility (MTF) Commander, who is dual-hatted, and in that capacity, executes the duties,

authorities, and responsibilities of both the MTF Director and the Service Commander. Air

Reserve Component (ARC) equivalent is a Guard Medical Unit Commander (GMU/CC) and the

Reserve Medical Unit Commander (RMU/CC) (or local equivalent).

8 DAFI48-151 2 MAY 2022

2.8.1. Provides Thermal Stress Program support to the Wing (or local equivalent) and

supported units including Geographically Separated Units and Munitions Support Squadron

sites. (T-1)

2.8.2. Directs the installation Thermal Stress Program and ensures it is supported with

adequate resources and staffing to implement the responsibilities outlined in this DAFI. (T-1)

2.8.3. Ensures timely care is provided for thermal-related illnesses. (T-1)

2.8.4. Ensures all medical staff who examine patients are aware of illnesses that may have a

correlation to thermal stress. (T-1)

2.8.5. ARC Medical Unit Commanders (or local equivalent) provide ARC Thermal Stress

Program support using organic capabilities or through a host-tenant support agreement as part

of the Occupational and Environmental Health Program in accordance with AFI 48-145,

Occupational and Environmental Health Program. (T-1)

2.9. Chief of Aerospace Medicine (SGP) or local equivalent.

2.9.1. Leads Aerospace Medicine execution of Thermal Stress Program responsibilities. (T-

2.9.2. Provides administrative and technical oversight of the Thermal Stress Program at

supported Geographically Supported Units and Munitions Support Squadron sites. (T-1)

2.9.3. Provides medical oversight of the Thermal Stress Program and ensures medically

appropriate risk assessment and medical surveillance activities are conducted. (T-1)

2.9.4. Trains MTF medical providers on potential thermal illnesses based on health risks

associated with the installation and corresponding International Classification of Disease

codes. (T-1)

2.9.5. Ensures providers make the final determination of an occupational illness on the illness

report and officially notifies Public Health (PH) for inclusion in the Air Force Safety

Automated System (AFSAS). (T-1)

2.9.6. As the Occupational and Environmental Health Working Group chair, annually reviews

the Thermal Stress Program effectiveness under the direction of the Aerospace Medicine

Council. The review shall include thermal illness trends and installation thermal risk

communication procedures. (T-1)

2.10. Bioenvironmental Engineering Flight Commander or local equivalent.

2.10.1. Manages the Thermal Stress Program for the wing or installation commander. (T-3)

2.10.2. Assists commanders and supervisors with integrating thermal stress prevention

information into risk management-based decision processes. (T-1)

2.10.3. Ensures thermal illness risk assessments are accomplished in accordance with AFI 48-

145 and AFMAN 48-146, Occupational & Environmental Health Program Management. (T-

2.10.4. Plans and programs for resources to support the Thermal Stress Program. Specific

resources the Bioenvironmental Engineering should purchase include (but not limited to) the

current versions of the American Conference of Governmental Industrial Hygienist

(ACGIH

)

DAFI48-151 2 MAY 2022 9

Threshold Limit Value (TLV

) and Biological Exposure Indices (BEIs) and ACGIH

’s

Documentation of the TLVs

and BEIs.

2.10.5. Conducts detailed workplace assessments of hot environments for thermal illness risk

using the DAF accepted standard of the ACGIH

Threshold Limit Values for Physical Agents

(ACGIH

TLV

-PA) found in AFMAN 48-146. (T-0) Uses the ACGIH

TLV

-PA as the

occupational exposure limit for heat stress exposure assessments. (T-0) Prioritizes heat stress

special surveillance in DOEHRS. (T-1)

2.10.6. Conducts detailed workplace assessments of cold environments for thermal illness risk

using the DAF accepted standard of the ACGIH

TLV

-PA found in AFMAN 48-146. (T-1)

Uses the ACGIH

TLV

-PA as the occupational exposure limit for cold stress exposure

assessments. (T-1) Prioritizes cold stress special surveillance in DOEHRS. (T-1)

2.10.7. Reviews new processes or operations (garrison or deployed) to prevent or control

potential thermal hazards at the earliest feasible stage. (T-1)

2.10.8. Determines the environmental contribution to thermal stress for the base population

by either:

2.10.8.1. Using direct reading instruments to conduct thermal stress environmental

monitoring at intervals designed to support mission requirements, (T-3) or

2.10.8.2. Estimating or modeling the environmental contribution to thermal stress. Uses

historic WBGT logs/records to estimate conditions or uses current weather data in

conjunction with an AFMRA approved model such as the Argonne National Laboratory

WBGT calculator, https://www.osha.gov/dts/osta/otm/otm_iii/otm_iii_4.html. (T-3)

Coordinates with unit system administrator when installing this software on a network

computer.

2.10.9. Employs mechanisms for dissemination of heat category (i.e., flag color) and frostbite

risk levels to installation personnel. (T-3)

2.10.10. Investigates proposed changes to existing processes or operations, including

equipment and facilities (including but not limited to construction plan reviews, the AF Form

332, Base Civil Engineer Work Request, or other base-specific process) for potential thermal

hazards to DAF personnel. (T-3)

2.10.11. Effectively communicates thermal illness risks and recommends controls and/or

corrective actions to organizational leadership, affected individual(s) and members of a related

similar exposure group. (T-1)

2.10.12. When supporting a site with no Bioenvironmental Engineering personnel assigned,

provides technical oversight for all thermal illness risk assessments at the Geographically

Supported Units or Munitions Support Squadron sites. The level of involvement may range

from simple oversight to performing the Occupational and Environmental Health assessments

based on the technical expertise of the available personnel and the host-nation agreements for

Outside Continental United States locations. (T-2)

2.10.13. Completes the workplace evaluation for occupational illness investigations and

ensures the investigation is entered into the AF Safety Automated System. (T-3)

10 DAFI48-151 2 MAY 2022

2.10.14. Documents reported thermal illnesses in the DOEHRS Incident Reporting Module.

(T-1)

2.10.15. Completes deployment site-specific thermal stress exposure documentation in

DOEHRS. (T-1)

2.10.16. Provides consultation, training and technical expertise to workplaces on thermal

hazards and regulatory requirements when applicable. (T-1)

2.10.17. Provides consultation on thermal illness exposures to the Occupational and

Environmental Health Working Group. Annually briefs installation thermal risk

communication procedures to the working group. (T-1)

2.10.18. Serves as a member of the Heat Alert Working Group when established. (T-3)

2.11. Public Health (PH) Flight Commander or local equivalent.

2.11.1. Ensures thermal illnesses classified as reportable medical events are entered into the

Air Force Disease Reporting System Internet in accordance with AFMAN 48-105, Public

Health Surveillance. (T-0)

2.11.2. Ensures any thermal illness requiring more than first aid is investigated and recorded

in the AFSAS. (T-1) Investigations shall be conducted in accordance with DAFMAN 91-224

and DAFI 91-204, Safety Investigations and Reports and be closed within 30 days. If the

investigation cannot be completed within this 30-day period, PH will request an extension from

the SGP and annotate the extension in AFSAS. (T-1)

2.11.3. Reviews each illness report in AFSAS after the provider makes the final occupational

illness determination to ensure internal (within individual report) and external (compared with

other similar illness reports) consistency and that all supporting data have been captured and

documented. (T-1) Ensures the AF Form 190, Occupational Illness/Injury Report generated in

AFSAS is filed in the patient’s hard copy medical record or uploaded to the electronic medical

record. (T-2)

2.11.4. Assists work area supervisors with accessing USAFSAM’s thermal stress training

materials. In coordination with Bioenvironmental Engineering, reviews the workplace-specific

training materials. Ensures workplace supervisors are modifying standardized training material

to include workplace and task specific details. (T-3)

2.11.5. Provides consultation on thermal illness exposures to the Occupational and

Environmental Health Working Group. Annually briefs thermal illness trends to the working

group. (T-1)

2.11.6. Serves as a member of the Heat Alert Working Group when established. (T-3)

2.12. Geographically Separated Unit Commander or Delegate (Medical Aid Station).

2.12.1. Ensures that Medical Aid Station staff provides Thermal Stress Program support as

defined in this DAFI to the extent possible within the scope of training, manpower and

equipment available. (T-3)

2.12.2. Ensures use of approved WBGT estimation calculator or obtains WBGT for use at

Geographically Supported Units. (T-3)

DAFI48-151 2 MAY 2022 11

2.12.3. Coordinates with the supporting MTF/SGP for Occupational and Environmental

Health Program support as needed to fulfill the requirements of this DAFI. (T-3)

2.13. Aerospace Physiology.

2.13.1. Provides aircrew members training on thermal risk and prevention in accordance with

AFMAN 11-403, Aerospace Physiological Training Program. (T-3)

2.13.2. At installations with clear “bubble” canopy aircraft (e.g., fighters and trainers),

assesses the FITS as described in Chapter 6 of this instruction. (T-3)

2.13.3. Disseminates the FITS to impacted units. (T-3)

2.14. USAFSAM.

2.14.1. USAFSAM Occupational and Environmental Health (USAFSAM/OE).

2.14.1.1. Provides technical consultation and detailed guidance (including information

about models, climate data, and injury mechanisms) to assist in assessing and managing

installation Thermal Stress Programs. (T-1)

2.14.1.2. Develops and maintains DAF thermal stress work-area specific training

templates. This training must be readily available DAF-wide. (T-1)

2.14.1.3. Identifies thermal illness risk reduction opportunities with DAF-wide

significance and evaluates costs/benefits. (T-1)

2.14.1.4. Analyzes DAF-wide, MAJCOM and installation thermal stress data in DOEHRS

to identify significant trends, answer questions/requests and provide summary analyses to

appropriate DAF and DoD authorities as requested. (T-1)

2.14.1.5. Develops DOEHRS data quality reports identified by AFMRA to meet metrics

reporting requirements. (T-1)

2.14.1.6. Recommends DAF-level Thermal Stress Program metrics to AFMRA/SG3PB.

(T-1)

2.14.2. USAFSAM Public Health (USAFSAM/PH).

2.14.2.1. Upon request, analyzes surveillance data (e.g., AF Disease Reporting System

Internet) and other DAF-specific data (e.g., AF Safety Automated System) for thermal

illness trends. (T-0)

2.14.2.2. Assists USAFSAM/OE in the development and maintenance of thermal stress

training materials as requested. (T-3)

2.15. Local Weather Flight (WF) or Detachment (Det) Commander or Reach-back Weather

Unit.

2.15.1. Supports the Thermal Stress Program with current weather data and information in

accordance with local procedures. (T-3) Note:, At locations without an assigned WF/Det, end-

users should submit a request for weather support to the 557th Weather Wing Directorate of

Operations (557 WW/A3) to obtain required weather information in accordance with AFMAN

15-129, Air and Space Weather Operations.

12 DAFI48-151 2 MAY 2022

2.15.2. Assists the Thermal Stress Program with obtaining and interpreting historical weather

data and information, to include the local installation, future deployed locations, and other

operational needs. (T-3)

2.15.3. Provides heat and cold weather advisories to the base populace to include weather

watches, warnings and advisories as documented in applicable host/tenant support agreements.

(T-2)

2.15.4. Serves as a member of the Heat Alert Working Group when established. (T-3)

2.16. Base Civil Engineer (BCE).

2.16.1. Establishes and maintains processes to ensure design and construction lead personnel

involve Bioenvironmental Engineering in all design review stages (conceptual, intermediate

and final), pre-construction meetings, pre-final and final inspections to identify and address

potential thermal illness concerns related to new construction and facility modification

projects. (T-3)

2.16.2. Serves as a member of the Heat Alert Working Group when established. (T-3)

2.17. Installation/Unit Safety Office.

2.17.1. Supports with training the unit and preventive medicine providers to produce a

strategic, comprehensive set of heat illness prevention countermeasures.

2.17.2. Serves as a member of the Heat Alert Working Group when established. (T-3)

2.18. Fitness Assessment Cell Manager. Ensures environmental conditions are evaluated for

thermal stress prior to implementing fitness assessments in accordance with DAFMAN 36-2905,

Air Force Physical Fitness Program and Chapter 4 of this instruction. (T-1)

2.19. Mission Swimming Pool Managers. Maintains mission swimming pool temperature in

accordance with AFMAN 48-114, Recreational Waters and Mission Training Pools to reduce

thermal stress during mission training operations. (T-1)

2.20. Unit/Organizational Commander.

2.20.1. Provides workers a safe and healthy work environment that complies with all

Occupational and Environmental Health program requirements identified in AFI 48-145 and

AFMAN 48-146, including thermal illness prevention captured in this AFI. (T-0)

2.20.2. Incorporates weather conditions, personal protective equipment (PPE)/clothing, and

anticipated workload into planning for new operations, changes to existing processes or

operations, equipment and facilities in coordination with Bioenvironmental Engineering. (T-

2.20.3. Supports installation and organizational level Thermal Stress Program objectives and

targets. (T-3)

2.20.4. Implements corrective actions for identified Thermal Stress Program discrepancies to

organizational facilities and processes. (T-1)

2.20.5. Ensures unit personnel are trained on the Thermal Stress Program as described in

paragraph 3.4 and paragraph 5.2 of this DAFI. (T-3)

DAFI48-151 2 MAY 2022 13

2.20.6. Recognizes the impact of thermal stressors and acclimatization on operations,

exercises, training events, ceremonies, and other installation functions, and makes appropriate

adjustments and accommodations. (T-3) Examples include:

2.20.6.1. Adjustment of work/rest cycles.

2.20.6.2. Provision of replacement fluids and electrolytes.

2.20.6.3. Provision of suitable personal protective equipment, gear, supplies, and DAF

approved devices to include heart-rate monitors and wearable physiological sensor

technology devices; and modifications as required to reduce risk in light of operational

requirements such as immersion ice baths, etc.

2.21. Workplace Supervisor. All workplace supervisors responsible for operations in

environments where there is a reasonable likelihood of heat or cold illness shall:

2.21.1. Ensure all Airmen and Guardians comply with applicable Thermal Stress Program

regulatory and policy requirements. (T-3)

2.21.2. Ensure thermal stress hazards are abated to the maximum extent possible. (T-3)

2.21.3. Monitor for signs of heat and cold-related illness regardless of the heat category or

frostbite risk level. (T-3)

2.21.4. Allow new workers to acclimatize to reduce the risk of thermal illness. Consults

Bioenvironmental Engineering for assistance developing an acclimatization plan. (T-1)

2.21.5. Ensure required Thermal Stress Program hazard controls are implemented and

functioning correctly, that PPE is available and used correctly in the workplace, and instruct

personnel on care/hygiene of their PPE. (T-3)

2.21.6. Inform Bioenvironmental Engineering of proposed changes to workplace equipment,

practices and/or procedures that may impact exposure to thermal hazards. (T-1)

2.21.7. Conduct workplace-specific thermal hazard training according to paragraph 3.4.2 and

paragraph 5.2.1 of this DAFI; document training in accordance with AFI 91-202, The US Air

Force Mishap Prevention Program. (T-0)

2.21.8. Develop thermal stress work-area specific training using USAFSAM’s template.

Consult PH if assistance is required to develop the work-area specific training. (T-2)

2.21.9. Notify PH of any occupationally-related thermal illnesses in accordance with AFI 48-

145 and AFI 91-202. (T-1)

2.22. Worker. All DAF personnel who work in environments where there is a reasonable

likelihood of heat or cold illness shall:

2.22.1. Understand the thermal risk aspects of work performed and complies with all risk

mitigation strategies and program requirements, including training, work practices and the

proper use, maintenance and storage of PPE. (T-3)

2.22.2. Report changes that may impact exposure to thermal hazards to the appropriate

supervisor; actively participate in workplace health hazard identification and health risk

assessments, to include wearing sampling/monitoring equipment. (T-3)

14 DAFI48-151 2 MAY 2022

2.22.3. Report any occupationally related thermal illnesses to workplace supervisor in

accordance with AFI 48-145 and AFI 91-202. (T-1)

DAFI48-151 2 MAY 2022 15

Chapter 3

HEAT STRESS PROGRAM ELEMENTS

3.1. Heat Illnesses. Heat illnesses are interrelated and include some degree of elevated body

temperature which may be complicated by deficits of body water. Heat illnesses include heat

stroke, heat syncope, heat exhaustion, heat cramps, hyponatremia, heat rash, rhabdomyolysis, and

other similar type issues.

3.2. Critical Elements of a Heat-Related Illness Prevention Program. According to National

Institute for Occupational Safety and Health (NIOSH), Criteria for a Recommended Standard:

Occupational Exposure to Heat and Hot Environments, there are four critical elements of a heat-

related illness prevention program: (1) Acclimatization Program; (2) Training Program; (3) Heat

Alert Program and (4) Medical Monitoring Program. Furthermore, and from a Joint Force Health

Protection warfighting perspective, commanders at all levels employ these critical elements in

preparation for and during Chemical, Biological, Radiological, and Nuclear (CBRN) operations

that require personnel to wear Mission Oriented Protective Posture (MOPP) and Individual

Protective Equipment. In effect, these combined elements are a critical enabling capability that

support overarching CBRN survivability and mission continuation. Furthermore, more details

regarding thermal stress while wearing MOPP is documented in Air Force Tactics, Techniques

and Procedures (AFTTP) 3-2.46, Multi-Service Tactics, Techniques, and Procedures for

Chemical, Biological, Radiological, and Nuclear Passive Defense.

3.3. Acclimatization Program. An effective acclimatization program will reduce the impact

heat stress will have on the core body temperature of the worker. NIOSH recommends gradually

acclimating the worker to his or her new environment by increasing the time of exposure each day

over a 7 to 14 day period. The time to acclimatize varies by worker based on individual risk

factors. Workplace supervisors shall consult Bioenvironmental Engineering for assistance

developing an acclimatization plan. (T-3) Bioenvironmental Engineering may refer to NIOSH’s

Criteria for a Recommended Standard: Occupational Exposure to Heat and Hot Environments

when assisting supervisors to develop acclimatization plans. Additionally, adequate hydration

following heat exposure is required for acclimatization, equal to or greater than volume of sweat

lost. It is known that a physically fit individual will acclimatize in half the time of a worker who

is not physically fit. Also, acclimatized workers who are not exposed to heat stress for a week or

more will need to re-acclimatize to the hot environment, typically completed in two or three days.

3.4. Training Program.

3.4.1. A heat stress training program ensures supervisors and workers are prepared to work

safely in hot environments.

3.4.2. Employee Heat Stress Training. Employee training shall include information about

acclimatizing, proper hydrating/fluid intake, recognizing and reporting heat-related illness

symptoms, giving appropriate first aid, proper care and use of heat-protective clothing, added

heat load caused by exertion/clothing/personal protective equipment, other factors that affect

heat tolerance (e.g., medications, alcohol, obesity, relevant health conditions such as sickle cell

trait status, etc.), and how to ensure weather data (i.e., WBGT) is part of the process for making

work/rest cycle decisions. (T-1)

16 DAFI48-151 2 MAY 2022

3.5. Heat Alert Program. While the Air Force publicizes the Summer Safety focus period from

Memorial Day through Labor Day and this provides a general awareness to the base population

regarding safety hazards during this time of year, a Heat Alert Program is recommended per

NIOSH to prepare the workforce for the upcoming inclement weather season. Installations in

warmer climates shall establish a cross functional Heat Alert Working Group (i.e.,

Bioenvironmental Engineering, Public Health, Safety, Maintenance, Civil Engineering, Weather,

Public Affairs and Medical personnel, etc.) with the intent of preparing the base to both minimize

the impact of heat stress to as low as reasonably achievable and to remind personnel on how to

recognize and respond to heat-stress related issues. (T-3) This committee may be included in

already occurring Safety programs for efficiency purposes and to reduce duplicative efforts. Bases

should use weather advisories to communicate when a heat alert is likely to occur. The weather

advisories shall be broadcast to the base to ensure the population is aware of the hazard and take

appropriate actions. (T-3)

3.6. Medical Surveillance Program. Workplace supervisors will track workers exposed above

the ACGIH® action limit in a hot environment. Workers exposed for more than 30 days per year

shall be presented to the Occupational and Environmental Health Working Group for medical

surveillance consideration. (T-3) Workers exposed above the ACGIH

action limit in a hot

environment for more than 30 days per year shall be presented to the Occupational and

Environmental Health Working Group for medical surveillance consideration. (T-3)

Bioenvironmental Engineering shall identify shops with Similar Exposure Groups who meet this

criteria and document in DOEHRS. (T-0) This data will be presented and reviewed during the

Occupational and Environmental Health Working Group meeting. (T-3) Medical surveillance

may include preplacement and periodic medical evaluations to include comprehensive work and

medical history, physical examination, assessment of medication, supplements, alcohol, or

caffeine use, assessment of obesity, and assessment of personal protective equipment as

determined appropriate by the Occupational and Environmental Health Working Group.

3.7. Special Surveillance Environmental Monitoring. ACGIH

uses metabolic heat of the

worker and WBGT to assess heat-related illness risk. WBGT monitoring may be conducted to

support both individual workplace and base population risk assessments.

3.7.1. WBGT. The WBGT is currently the industry standard according to NIOSH and

ACGIH

for predicting the risk of thermal illness. Detailed analysis of the influence of the

environment on thermal stress requires knowledge of the following four basic parameters: air

temperature, mean radiant temperature, air speed and absolute humidity. The WBGT combines

the measurement of two derived parameters, natural wet-bulb temperature (T

nwb

) and the black

globe temperature (T

), and, in some situations, the measurement of the basic parameter, dry-

bulb (air) temperature (T

). During periods of hot weather, the WBGT is determined and the

appropriate Heat Stress Risk and Flag Color can be determined using Table 3.1The WBGT

formulae can utilize either

F or

C, as long as usage is consistent; the equations are as follows:

3.7.1.1. WBGT = 0.7(T

nwb

) + 0.2(T

) + 0.1(T

) (outdoors)

3.7.1.2. WBGT = 0.7(T

nwb

) + 0.3(T

) (with no radiant load)

3.7.2. Special Assessment Environmental Monitoring. WBGT monitoring shall be conducted

in individual work centers to support detailed risk assessments in accordance with the

American Conference of Governmental Industrial Hygienist Threshold Limit Values

for Heat

Stress and Strain. (T-1)

DAFI48-151 2 MAY 2022 17

3.7.3. Installation Environmental Monitoring. WBGT monitoring for the base population

shall be accomplished periodically to mark the transition from one thermal illness risk stage to

another at intervals designed to support mission requirements. (T-1) The data collected shall

be compared to reference values in Table 3.1 to determine flag conditions and communicated

as appropriate. (T-1) Alternatively, approved modeling tools shall be used in accordance with

paragraph 2.10.8.2 of this DAFI including the Argonne National Laboratory WBGT

calculator (Liljegren). (T-3)

3.8. Heat Stress Guidelines. Table 3.1 provides workload, heat categories, WBGT temperature

ranges, flag colors, recommended work/rest cycles and water intake for easy, moderate, and hard

work.

Table 3.1. Work/Rest Times & Fluid Replacement Guide, Technical Bulletin 507 (US

Army, 2003).

3.8.1. Modifications to the WBGT for clothing. Normal duty-type uniforms, overalls, and

long-sleeved civilian work clothes do not drive any adjustment to the WBGT.

3.8.2. Wearing a second layer of clothing, such as chemical protective gear (MOPP gear) or

firefighting bunker gear adds 10°F to the WBGT measurement for light work, and 20°F for

moderate to hard work. A summary of modifications to WBGT for clothing is in Table 3.2.

3.8.3. The addition of PPE can or will increase the thermal illness risk to the worker.

Additionally, wear of body armor adds an additional 5°F to the WBGT measurement.

18 DAFI48-151 2 MAY 2022

Table 3.2. Modifications to WBGT for Body Armor/MOPP Gear Based Upon Workload.

Addition to WBGT (

Easy Work

Moderate Work

Hard Work

Normal Duty-Type Uniforms (OCP/ABU, Overalls

or Long-Sleeved Work Clothes)

Body Armor

Second Layer of Clothing or MOPP Gear

Total Maximum Addition to WBGT Based Upon

Work-Rate and PPE

DAFI48-151 2 MAY 2022 19

Chapter 4

THERMAL STRESS FOR AIRMEN/GUARDIANS IN FORMAL TRAINING COURSES

AND PHYSICAL TRAINING

4.1. Thermal Illness Prevention for Airmen/Guardians in Training. Thermal illness

prevention, particularly heat illness prevention, is a high priority for Basic Military Training, and

in the preparation and training of Special Warfare and Security Forces Airmen. In order to

overcome the inherent training restrictions created by exclusively following the work/rest cycle,

the training unit will work in partnership with unit safety and preventive medicine providers to

produce a strategic, comprehensive set of heat illness prevention countermeasures. (T-1)

4.1.1. Heat and cold illness prevention will be targeted to the unique needs of each training

objective/course, and will be taught and integrated into risk management aspects of each

training objective/course. (T-1)

4.1.2. A defined risk management matrix will be developed for each high-risk training event

in the training unit. (T-1) This approach provides a level of heat and cold illness prevention

that exceeds the work/rest cycle while assuring training standards and mission goals are

accomplished.

4.1.3. Thermal illness prevention elements of the risk management matrix will be reviewed

and approved by preventive medicine providers upon initial development and re-reviewed in

the event of any heat illnesses. (T-1)

4.2. Unit Physical Training. Commanders and unit physical training leaders (PTLs) shall

consider thermal flag conditions for warmer temperatures and wind chill and precipitation for

colder temperatures to determine when and how to train the unit. (T-1) The general

recommendation is unit physical training be conducted when the environmental stressors are at a

minimum, typically in the early morning during the summer timeframe and afternoons during the

winter timeframe.

4.2.1. Unit physical training leaders shall take into account the activity planned, work/rest

cycles and available water sources prior to the activity. (T-1) Depending on how strenuous the

training, unit physical training leaders shall apply the work/rest cycles and fluid replacement

guidelines from Table 3.1 appropriately. (T-1) Unit physical training shall not occur during

Black Flag conditions in Figure 4.1 (T-3)

4.2.2. It is important to note, the heat category (flag condition) and work-rest cycles referenced

in Table 3.1 are intended for a worker at a work-site. They are not applicable to certain high

intensity sports or unit physical training activities. Some high intensity events may result in

metabolic heat production rates well above 800 watts exceeding the definition of very hard

work in Table 3.1 Two common examples include a 5-mile run in <40 minutes and a 12-mile

march with 55 pounds completed in <180 minutes. One way to mitigate risk is to apply

sports medicine heat stress categories during high intensity physical training events. Both

military and sports medicine heat categories use the same color scheme, but sports medicine

assigns flag conditions at lower temperatures to account for higher metabolic heat production

during competitive athletic events. Sports medicine heat categories are summarized in Figure

4.1 Unit physical training leaders shall use the sports medicine flag conditions for high

intensity sports in Figure 4.1 when planning high intensity physical activities. (T-3)

20 DAFI48-151 2 MAY 2022

4.2.2.1. Low Caution: Low health risk for normal activities in these temperature ranges.

4.2.2.2. Modify Activity: Moderate health risk for activities in these temperature ranges.

Consider limiting activity or require breaks and adequate hydration.

4.2.2.3. High Caution: High health risk for activities in these temperature ranges.

Activities should be modified and ensure members have adequate hydration.

4.2.2.4. Suspend Activity: Severe health risk for activities at or above these temperature

ranges. Activities should be suspended.

Figure 4.1. WBGT Category Comparison Based Upon Heat Production Rate in Watts (W).

4.2.3. Preventing cold weather health issues can be managed by understanding the hazards

and the techniques to mitigate the risks. Hazards include air temperatures below 40 °F, wetness,

wind, and lack of shelter/rewarming. Additionally, there are personal risk factors that include

DAFI48-151 2 MAY 2022 21

hydration, nutrition, previous cold injuries, tobacco and/or alcohol use, low activity, and sleep

deprivation.

4.2.3.1. Heat dissipates when exposed to cold temperature and when coupled with wind,

heat is dissipated even quicker. Higher winds increases how fast heat is dissipated. A lower

wind chill can increase the rate at which certain cold-weather health issues can develop

(i.e., frostbite and hypothermia). Therefore, wind chill needs to be factored for determining

outside training decisions during colder temperatures.

4.2.3.2. PTLs must be aware of precautions for conducting training outside in extreme

weather, such as wearing proper clothing and using appropriate equipment.(T-3) Figure

5.1 (Chapter 5) provides the wind chill temperature as well as the time it could take to

develop frostbite.

4.2.3.3. Cold weather thermal illness prevention recommendations are provided in Table

4.1 These recommendations must be coupled with adequate protection from the weather

and be based on the wind-chill temperature.

Table 4.1. Recommended Cold Weather Thermal Illness Prevention.

Wind-Chill

Temperature (°F)

Recommended Action

≤30

Awareness of potential cold injury

≤ 25

Provide/wear additional protective clothing

≤ 15

Modify activity to allow more frequent opportunities to re-warm; 1 hour outside with

20 minutes of rewarm

≤ 0

Cancel Activity

4.2.4. Fitness Assessments.

4.2.4.1. Acclimatization for physical fitness purposes can take much longer than the

typical 7-14 days for a worker to acclimatize to a new work-site. Acclimatization for

physical fitness purposes will be done in accordance with DAFMAN 36-2905. (T-1)

4.2.4.2. WBGT must be within allowable parameters in accordance with DAFMAN 36-

2905 prior to the start of the walk/run test. (T-1) Fitness assessments include periods of

work and rest between exercises and will result in metabolic heat production rates below

800 watts thereby not meeting the definition of high intensity sports. The flag conditions

for high intensity sports in Figure 4.1 are not appropriate for fitness assessments.

22 DAFI48-151 2 MAY 2022

Chapter 5

COLD STRESS PROGRAM ELEMENTS

5.1. Cold Illnesses. Cold illnesses can be broken down into three categories: cold/dry freezing

illnesses (frostbite), cold/wet non-freezing illnesses (trench foot and chilblains) and hypothermia.

5.2. Critical Elements of a Cold-Related Illness Prevention Program. To prevent cold-

weather injuries, engineering and administrative controls will be implemented at work-centers,

personal-protective equipment/clothing requirements will be issued to minimize skin contact with

freezing temperatures, and work-rest cycles will be based upon the frostbite risk obtained from

Figure 5.1 and the prevention guidelines in Table 5.1 (T-1)

Figure 5.1. Wind Chill & Frostbite Time (National Weather Service, 2001).

5.2.1. Employee Cold Stress Training. Employee training shall include information about risk

factors that contribute to cold stress, recognizing and reporting cold-related illness symptoms,

giving appropriate first aid, general methods to prevent cold stress, and how to use weather

data (i.e., frostbite risk level) to make specific risk mitigation decisions using Figure 5.1 and

Table 5.1 (T-1)

5.2.2. Conditions at the actual worksite. It is important to keep in mind that the actual

environmental work conditions may vary significantly from where the weather data is

collected. If workers are on the flight-line exposed to propeller/rotor-generated wind the

conditions could be much more severe. Additionally, if a Geographically Supported Unit is at

a significantly higher altitude than where the weather station is located then one must as a

general rule decrease the air temperature 3.6

F for every 1,000 feet increase in altitude.

Additionally, frostbite illnesses occur at differing temperatures based upon whether or not the

skin is dry (~28

F) or wet (~30

F). Lastly, if the ambient air temperature is >32

F there is no

risk of frostbite despite the wind-speed.

DAFI48-151 2 MAY 2022 23

Table 5.1. Preventive Measures to Reduce Frostbite Risk, Technical Bulletin 508 (US

Army, 2005).

Frostbite Risk Level

Preventive Measures

Low Risk

 Recommended work/rest (W/R) cycle: 50 minutes work/10 minutes

warming

 Increase surveillance with self and buddy checks

 Wear appropriate layers and wind protection for the work intensity

 Cover exposed flesh if possible

 Wear Vapor Barrier (VB) boots below 0°F

 Provide warming facilities below 20 °F

 Avoid sweating.

High Risk

Frostbite time = 30 mins

 Recommended W/R cycle: 40 minutes work/20 minutes warming

 Mandatory buddy checks every 20–30 minutes

 Wear appropriate layers & All Purpose Environmental Clothing System

(APECS)

 Protect head, face and hands

 Cover exposed flesh

 Wear VB boots below 0 °F

 Provide warming facilities

 Avoid sweating

Severe Risk

Frostbite time = 10 mins

 Recommended W/R cycle: 30 minutes work/30 minutes warming

 Mandatory buddy checks every 10 minutes

 Wear appropriate layers and APECS or cold weather parka

 Protect head, face and hands

 Wear VB boots

 Provide warming facilities

 Work groups of no less than two personnel

 No exposed skin

 Stay active

 Avoid sweating

Extreme Risk

Frostbite time = 5 mins

 Mission critical work only due to extreme risk

 Keep task duration as short as possible

 Wear appropriate layers, cold weather parka, wind protection

 Protect head, face and hands

 Wear VB boots

 Provide warming facilities

 Work groups of no less than two personnel

 No exposed skin

 Stay active

 Avoid sweating

24 DAFI48-151 2 MAY 2022

Chapter 6

FIGHTER INDEX OF THERMAL STRESS (FITS)

6.1. FITS. The FITS was developed in 1979 (Nunnley and Stribley) to provide a measure of the

thermal stress experienced by aircrew in high performance aircraft with canopies and

environmental control systems, engaged in combat sorties at low altitudes, in direct sunlight or

light overcast, and in elevated outside ambient temperatures. The FITS table uses ground dry bulb

temperature and dew point to yield an estimate of cockpit thermal stress.

6.2. Assessing FITS Reference Values. In hot environments, the FITS provides a measure of

thermal stress which can be used to determine risk of aircrew heat illness. The calculated values

assume an Aircrew Equipment Assembly of 1.5-2.0 clothing and thermal insulation (clo) value,

roughly equivalent to light, summer Aircrew Equipment Assembly; therefore, the FITS is not

appropriate for cold weather, immersion suit or other types of individual protective equipment with

higher clo values.

6.3. FITS Tables Using Dew Point and Dry Bulb Temperature. The FITS Table 6.1 utilize

dew point and the dry-bulb temperature (T

) to determine the appropriate risk category.

6.4. FITS Actions. FITS reference values and their associated zones are not exact demarcations,

but represent the temperatures and humidity at which aircrews begin to experience heat-stress-

related effects. These effects may vary with the individual, the particulars of the ground and flight

aspects of the mission, the particular clothing worn, and so forth. The following FITS action,

therefore, are guides, rather than directives.

6.4.1. FITS Normal Zone (Green). The Normal Zone is subjectively hot, but normally safe,

and generally covers FITS Reference Values under 90 °F. The following procedures shall be

implemented:

6.4.1.1. Be alert for symptoms of heat stress. (T-3)

6.4.1.2. Ensure adequate fluid intake. (T-3)

6.4.2. FITS Caution Zone (Yellow). The Caution Zone includes conditions that are tolerable

if adequate precautions are taken, and generally covers FITS Reference Values between 90 °F

and 99 °F. The following procedures shall be implemented:

6.4.2.1. Be alert for symptoms of heat stress. (T-3)

6.4.2.2. Drink plenty of non-caffeinated fluids. (T-3)

6.4.2.3. Avoid exercise 4 hours prior to take off. (T-3)

6.4.2.4. Limit ground operations time outside an air-conditioned environment to 90

minutes.

DAFI48-151 2 MAY 2022 25

Table 6.1. Fighter Index of Thermal Stress Chart (

F).

6.4.3. FITS Danger Zone (Red). The Danger Zone represents conditions that induce

progressive heat storage and dehydration sufficient to affect crew performance during normal

low-level missions, and comprise FITS Reference Values over 100 °F. When the FITS

Reference Value is over 115 °F, consider limiting or cancelling non-essential flight operations,

as the thermal stress constitutes a serious drain on physiological reserves. The following

procedures shall be implemented:

6.4.3.1. Minimum recovery time is two hours (landing time to next take off). (T-3)

26 DAFI48-151 2 MAY 2022

6.4.3.2. Limit ground operations time outside air-conditioned environment to 45 minutes.

(T-3)

6.4.3.3. If possible, wait in a cool shaded area if the aircraft is not ready to fly. (T-3)

6.4.3.4. Complete a maximum of two aircraft inspections, two exterior inspections on

initial sorties, and one exterior inspection on subsequent sorties for fighters and trainers.

6.4.3.5. Undergraduate Flying Training solo students should be limited to one exterior

aircraft inspection per sortie.

ROBERT I. MILLER

Lieutenant General, USAF, MC, SFS

Surgeon General

DAFI48-151 2 MAY 2022 27

Attachment 1

GLOSSARY OF REFERENCES AND SUPPORTING INFORMATION

References

10 USC 9013, United States Code, Title 10 – Armed Forces, Subtitle D – Air Force, Section

9013 – Secretary of the Air Force, 29 March 2022

29 CFR 1904, Recording and Reporting Occupational Injuries and Illnesses, 3 May 2017

AFPD 48-1, Aerospace & Operational Medicine Enterprise (AOME), 7 June 2019

AFPD 90-8, Environment, Safety, and Occupational Health Management and Risk Management,

23 December 2019

AFI 33-322, Records Management and Information Governance Program, 28 July 2021

DAFI 90-160, Publications and Forms Management, 14 April 2015

AFI 48-145, Occupational and Environmental Health Program, 11 June 2018

AFI 90-801, Environment, Safety, and Occupational Health Councils, 9 January 2020

AFI 91-202, The US Air Force Mishap Prevention Program, 12 March 2020

DAFI 91-204, Safety Investigations and Reports, 10 March 2021

AFMAN 11-403, Aerospace Physiological Training Program, 13 August 2020

AFMAN 15-129, Air and Space Weather Operations, 9 July 2020

DAFMAN 36-2905, Air Force Physical Fitness Program, 11 December 2020

AFMAN 48-105, Public Health Surveillance, 26 June 2020

AFMAN 48-114, Recreational Waters and Mission Training Pools, 23 July 2019

AFMAN 48-146, Occupational & Environmental Health Program Management, 15 October

2018

AFTTP 3-2.46, Multi-Service Tactics, Techniques, and Procedures for Chemical, Biological,

Radiological, and Nuclear Passive Defense, 1 May 2016

AFTTP 3-4, Airman’s Manual, 11 January 2019

DAFMAN 91-224, Ground Safety Investigation and Hazard Reporting, 21 January 2022

American Conference of Governmental Industrial Hygienists (ACGIH

) Threshold Limits Values

(TLV

) and Biological Exposure Indices (BEI

), 2021

Argonne National Laboratory (ANL), Wet Bulb Globe Temperature (WBGT) Version 1.2,

Chicago, IL, 2008

Cheuvront S & Hosokawa Y. “The WBGT Index: A Primer for Road Race Medicine.”

Endurance and Sports Medicine, Fall/Winter 2018, pp. 22-26

Liljegren, J et al. “Modeling the Wet Bulb Globe Temperature Using Standard Meteorological

Measurements.” Journal of Occupational and Environmental Hygiene, Vol 5:10, August 2008,

pp.645-655

28 DAFI48-151 2 MAY 2022

National Institute for Occupational Safety and Health, “Criteria for a Recommended Standard:

Occupational Exposure to Heat and Hot Environments,” February 2016

National Weather Service, “Wind Chill Temperature Index,” 1 November 2001

Nunnley A & Stribley R F. “Fighter Index of Thermal Stress (FITS): Guidance for Hot Weather

Aircraft Operations.” Aviation, Space & Environmental Medicine, Vol 50, 1979, pp.639-642

Technical Bulletin Medical 507 (US Army), Heat Stress Control and Heat Casualty

Management, 7 March 2003

Technical Bulletin Medical 508 (US Army), Prevention and Management of Cold-Weather

Injuries, April 2005

Adopted Forms

AF Form 190, Occupational Illness/Injury Report

AF Form 332, Base Civil Engineer Work Request

AF Form 847, Recommendation for Change of Publication

Abbreviations and Acronyms

ACGIH®—American Conference of Governmental Industrial Hygienists

AF—Air Force

AFI—Air Force Instruction

AFMAN—Air Force Manual

AFMRA—Air Force Medical Readiness Agency

AFPD—Air Force Policy Directive

AFTTP—Air Force Tactics, Techniques, and Procedures

APECS—All Purpose Environmental Clothing System

AFSAS—Air Force Safety Automated System

ARC—Air Reserve Component

BCE—Base Civil Engineer

BEI—Biological Exposure Index

CBRN—Chemical, Biological, Radiological and Nuclear

clo—Clothing and Thermal Insulation Value

DAF—Department of the Air Force

Det—Detachment

DOEHRS—Defense Occupational and Environmental Health Readiness System

FITS—Fighter Index of Thermal Stress

FR—Federal Register

DAFI48-151 2 MAY 2022 29

GMU—Guard Medical Unit

MAJCOM—Major Command

MOPP—Mission Oriented Protective Posture

MTF—Medical Treatment Facility

NIOSH—National Institute for Occupational Safety and Health

PPE—Personal Protective Equipment

PH—Public Health

PTL—Physical Training Leader

RMU—Reserve Medical Unit

SORN—System of Record Notice

TLV®—Threshold Limit Value

US—United States

USAF—United States Air Force

USAFSAM—USAF School of Aerospace Medicine

VB—Vapor Barrier

WBGT—Wet Bulb Globe Temperature

W—Watts

WF—Weather Flight

W/R—Work/Rest

Terms

Acclimatization—Acclimatization is the physiological adaptation of an individual to changes in

climate or environment, such as temperature, humidity, or altitude.

Black Globe Temperature (Tg)—Is a measurement that integrates radiant (or direct sunlight)

heat exchange and convective heating or cooling into one value. The WBGT index is based on the

response of the six inch diameter globe. This measurement uses a six inch diameter hollow copper

sphere painted matte black on the outside and containing an unshielded dry-bulb thermometer in

the center of the sphere. Note:, some current meters use a smaller sphere that is correlated to a six

inch sphere.

Cold Illness—Acute and chronic illnesses including cold/dry freezing illnesses (frostbite),

cold/wet non-freezing illnesses (trench foot and chilblains) and hypothermia. For the purpose of

AFSAS reporting, when greater than first aid is rendered the above cold illnesses will be reported

as occupational illnesses not injuries.

Cold Stress—Environmental and/or personal conditions that tend to remove body heat and

decrease body temperature.

30 DAFI48-151 2 MAY 2022

Dry—Bulb (air) Temperature (T

)—Is the temperature measured with an ordinary alcohol-in

glass, or mercury-in-glass thermometer whose bulb is kept dry and shielded from direct sun

radiation.

First Aid—Any initial one-time treatment and any follow-up visit for observation of minor

thermal illness that does not ordinarily require care. Such one-time treatment and follow-up visit

for observation is considered first aid, even though provided by a physician or medical

professional. First aid as defined in 29 CFR 1904.7 includes use of non-prescription medicine at

non-prescription strength; drinking fluids for relief of heat stress; cleaning, flushing or soaking

wounds on the surface of the skin; or using hot or cold therapy. Treatment outside this list is

considered medical treatment greater than first aid. See 29 CFR 1904 and DAFI 91-204 for further

guidance on illness classifications.

Heat Illness—Traditionally heat illness has been divided into heat exhaustion and (exertional)

heat stroke. In practice the division is difficult to define; thus, for the purpose of this DAFI the

term ‘Heat Illness’ is all encompassing and applies to an individual who collapses as the result of

a rise in core body temperature. For the purpose of AFSAS reporting, when greater than first aid

is rendered the following will be reported as occupational illnesses not injuries: dehydration, heat

exhaustion, heat syncope, heat stroke, heat cramps, rhabdomyolysis or other similar type issues.

Heat Stress—The net heat load to which an Airman/Guardian is exposed from the combined

contributions of heat generated in the body (metabolic heat), environmental factors, and clothing

worn which results in an increase in heat storage in the body.

Humidity—An expression of the quantity of water vapor mixed with the other atmospheric gases.

Natural Wet—Bulb Temperature (T

nwb

)—Is the temperature measured with a thermometer,

with a wet wick fitted closely over the bulb or electronic sensor.

Thermal Illness—General term referencing acute and chronic heat and cold illnesses.

Thermal Stress—The physiological stress experienced by the human body as a result of exposure

to hot and cold environments. Thermal stress includes both heat stress and cold stress.

Wet-Bulb Globe Temperature (WBGT)—Is an empirical index of heat that provides an index

that corresponds to the behavior of the human body under heat strain.