1 Heat Stress and Carbon Monoxide Exposure During C-130 Vehicle Transportation Dor A, Pokroy R M.D., Zilberberg M MHA, Barenboim E M.D. MHA, Goldstein L M.D. MHA The IAF Surgeon General HQ, ISRAEL

INTRODUCTION  The C-130 is often used for military vehicle airlift Loading vehicles with running engines (“hot”) The hot climate Direct convection heating of the aircraft heat stress to the aircrew Heat stress effects performance

Driving on and off C-130 : A potential contamination by exhaust gases. Carbon Monoxide (CO) Fatigue Headache Nausea CO and high altitude flights

OBJECTIVES Investigating heat stress and CO exposure during C-130 vehicle transportation, Ensuring the safety of C-130 aircrew.

METHODS

METHODS The cabin Heat Stress index (wet bulb globe temperature- WBGT) and CO levels before (control) and after vehicle loading were compared 2- and 3-vehicle transportations Day and night transportations were compared

Dry bulb temperature and cabin heat stress index - measured at 10-min intervals Runway ambient temperature - before takeoff and after landing METHODS

Carbon Monoxide- 30 sec intervals using an inorganic gas monitor Compared with the recommended exposure limits of the ACGIH (American Conference of Governmental Industrial Hygienists) METHODS

RESULTS Heat Stress Index vehicle transportation Heat Stress Index > recommended limit (28°C) Until vehicle unloading Activated cooling system Heat Stress higher in all flights (transport and control) during the day than the night flights (p< ).

During day flights, 2 vehicle transportation flight had a significantly lower mean WBGT than the 3 vehicle transportation (27.8°C vs. 35.8°C, p=0.0001) While no difference was recorded between the 2 or 3 vehicle transport during the night flights (20.2°C vs. 20.5°C, p=0.46) RESULTS

During day flights, 2 vehicle transportation flight had a significantly lower mean WBGT than the 3 vehicle transportation (27.8°C vs. 35.8°C, p=0.0001) While no difference was recorded between the 2 or 3 vehicle transport during the night flights (20.2°C vs. 20.5°C, p=0.46)

Cabin Heat Stress index > TLV in 74% of the measurements during daytime flights Heat Stress directly related to flight duration in day and night transport flights Heat Stress directly related to flight duration in day and night transport flights (P=0.001 & P= 0.001) (P=0.001 & P= 0.001) RESULTS

Fig 1: Heat stress during day flights Note the increase in WBGT after vehicle loading, which continued to increase for the full flight duration of 140 minutes

Fig 2: Heat stress during night flights Note the increase in WBGT after vehicle loading

the mean CO levels were significantly higher in transporting 3 than 2 vehicles. During the fourth flight the mean cabin CO level just exceeded the CO threshold limited value (TLV). RESULTS

RESULTS

DISCUSSION Solar heating of C-130 body on the runaway in day flights before loading corresponds with other studies “Hot” Vehicle loading caused sharp Heat Stress index increase above the accepted ACGIH limit

3- vehicle night flight: CO just above the TLV 3-vehicle day flight: CO approached Action Level Warning level -recommend preventive actions Other studies - correlation between increased CO levels the number of engines acting simultaneouslyDISCUSSION

CO TLV is based on an 8-h work shift. Our longest transport duration - only 160 min CO exposure is well below the TLV-time weighted average formula not considered hazardous CO levels in ambient air Major drawback- CO levels in ambient air Vs blood CO monitoringDISCUSSION

C-130 crews are exposed to Heat Stress and CO during “hot” vehicle transportation The air conditioning system of the early C-130 models provides inadequate cooling under conditions of severe heat stress SUMMARY

Recommendation - increasing the natural ventilation of the plane before takeoff by opening the front and the rear door during ground stand-by Recommendation - using industrial fans on the runway during loading if the ambient temperature exceeds 28°C. SUMMARY

Further investigation: Aircrew blood CO monitoring + ventilation recommendations SUMMARY

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