Health Hazard Assessment (HHA)

Hazard Category - Temperature Extremes

Last Updated: August 02, 2018
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​Information on temperature extremes.


Data Requirements and Initial Recommendations.
(1) Test heating and cooling performance in accordance with Test Operations Procedure (TOP) 2-2-816, TOP 1-2-807, and/or TOP 1-2-610 (references 1 through 3), simulate all heat gains, and provide Wet Bulb Globe Temperature data at occupant head, chest and foot positions to support a definitive health hazard assessment.  Test data should demonstrate that the materiel's heating and cooling system can maintain the required temperature so that a comprehensive assessment of heat and cold stress can be performed.   

(2) Design heating and cooling performance to meet or exceed the performance/design criteria requirements contained in Military Standard (MIL-STD) 1472G (reference 4).

Health Effects.
Soldier exposures to excessive levels and duration of either heat or cold stress may cause vigilance and performance decrements, temporary or permanent injury, and death.

Medical Criteria.
(1) Army system specifications routinely require operation in basic and hot climactic design types (-25 degrees Fahrenheit (°F) to120 °F) as defined in Army Regulation (AR) 70-38 (Reference 5) and is intended to operate anywhere Joint Forces deploy. 

(2) Guidance addressing ambient temperatures, temperature uniformity, humidity, micro-climate cooling and correction factors for the wear of protective clothing are provided in MIL-STD-1472G, paragraphs and 5.6.6 for personnel enclosures/shelters and vehicle cabs, respectively (reference 4).

(3) Mobile personnel enclosures or shelters used for detailed work or occupied for extended periods must have a cooling system designed to maintain the effective temperature or corrected effective temperature not greater than 85 °F.  The system will be designed so that cold air discharge is not directed on Soldiers.  The hot climate comfort zone for inhabited spaces is defined as 66 °F to 75 °F. 

(4) The heating system should be designed to maintain the interior dry bulb temperature above 50 °F.  The heating system will also be designed so that hot air discharge is not directed on Soldiers.  The cold climate comfort zone for inhabited compartments/shelters is defined as 65 °F to 70 °F (reference 4).

(5) Traditional vehicle cabs are to be equipped with an air conditioning system capable of meeting the performance requirements in MIL-STD-1472G, paragraph, whenever the vehicle's mission profile requires Soldiers to occupy the cab for period of greater than 30 minutes with a temperature greater than 85 °F.   Traditional vehicle cabs must have a heating system capable of maintaining temperatures above 68 °F during occupancy when Soldiers do not wear Arctic clothing and exposure exceeds three hours.  When Soldiers wear Arctic clothing, cab heaters are to maintain a temperature of not less than 41 °F at the minimum ambient design operating temperature of the vehicle when moving at two-thirds maximum speed and the defrosters operating at maximum capacity.  The heater is to achieve performance requirements within one hour of operation (reference 4).

(1) Test Operations Procedure (TOP) 2-2-816, Tracked Vehicle Temperature Tests, 1987.

(2) Test Operations Procedure (TOP) 1-2-610, Human Factors Engineering Part I – Test Procedures, 15 May 90.

(3)  Test Operations Procedure (TOP) 1-2-807, Thermal Comfort Testing for Vehicle Operator/Passenger Workspaces (Truck Cabs), 9 Oct 2007.

(4) Military Standard (MIL-STD) 1472G, Department of Defense Design Criteria Standard – Human Engineering, 11 Jan 12.

(5) Army Regulation (AR) 70-38, Research, Development, Test and Evaluation of Materiel for Extreme Climatic Conditions, 15 Sep 79.

Supplemental References.
(1) Military Handbook (MIL-HDBK) 759C, Department of Defense Handbook for Human Engineering Guidelines, 31 Jul 95.