J Royal Naval Medical Service 2010, 96.3 150-163

Clinical Managing the risk of heat illness on board Type 23 deploying to the Arabian Gulf

T Stevenson, D Roiz de Sa

Abstract following the Six Day War of 1967. The Egyptian Temperature extremes are commonplace in Army at the time were issued minimal supplies the Middle East, varying between 30 oC and of water, compared to the Israeli Army where 50 oC. During the summer months, soldiers were issued 1L water per hour per temperatures reach 50 oC consistently, with person (5). Egypt suffered approximately 20,000 high humidity and sea temperatures rarely casualties, the majority of which were attributed dropping below 33 oC (1). Sailing from the to heat illness, whereas Israel suffered no temperate climate of the UK, Ship’s crews are reported cases of heat illness (6). For a deploying to these extremes and working in population indigenous to a hot climate to suffer spaces within the Ship where temperatures such appalling rates of heat illness suggests that climb as high as 52 oC for at least 4 out of 6 management of the risks of heat illness is months. Type 23 frigates (T23) were designed paramount to operational success within a for anti- warfare (2)(anecdotally population of British service personnel deploying assumed to be North Sea based), yet now to climatic extremes. In its most mild form the deploy continuously to hotter climates which effects of heat stress and strain can result in subjects personnel to increased heat stress symptoms ranging from dizziness, headaches, a putting them at risk of heat injury. These risks reduced capacity for physical work, reduced can be minimised with simple measures such cognitive and psychomotor performance (7,8) and as maintaining hydration, rest periods outside increased risks within the workplace of hot workspaces and finally cooling environment (9). In its most severe form it can techniques such as inserting the arms up to lead to collapse, coma, multiple organ failure and the elbows in cool water for 10 minutes. death. Reducing the risks of heat stress and During the 4 months spent in the Arabian Gulf prevention of heat illness in an operational unit of a 6 month tour, during the summer of 2010, involves identifying risks and managing them personnel on board the T23 HMS accordingly. This paper will discuss the suffered no cases of heat illness contributing factors of heat stress that personnel despite the risks, due to employing these on operational warships can expect to find simple strategies. themselves exposed to during deployments to the Middle East such as OP TELIC or CALASH, Introduction and the methods used to minimise the risks of Heat illness is an all inclusive term which heat illness occurring in those personnel. The encompasses several conditions including those examples used will be from HMS SOMERSET, a of heat exhaustion and heatstroke (3). The deployed to the Gulf on OP effects of heat on health and wellbeing appear in TELIC in summer 2010. some of the earliest written documents of mankind as far back as Homer’s Iliad (ca 1100 Environment of the Gulf BC) and its significant effects on various military Ships can expect a rise in temperature once endeavours have regularly been reported in they have passed out of the Mediterranean history (4). An interesting example can be found Sea through the Suez Canal. Transit through

150 Managing the risk of heat illness on board Type 23 frigates 151

the Bab el-Mandeb Strait (BAM) into the Gulf the Cold War, with the first class of T23 ships of Aden (GOA) brings ships to the main area of appearing in 1984 (2). It was thus designed to operations for CALASH deployments and be conducting patrols mainly in the North counter-piracy patrols. Moving north east to Atlantic and North European waters; however the Gulf of Oman (GOO) then North West to its roles now are far more versatile. The design transit through the (SOH) of the T23 appears to presage a secondary role brings ships to the Arabian Gulf where in more tropical climates; the ship has an CALASH deployments extend across the onboard Chilled Water System (CWS) Southern Arabian Gulf (SAG) and Central responsible for cooling the equipment and Arabian Gulf (CAG) and TELIC deployments machinery to allow them to remain operational. take place in the Northern Arabian Gulf (NAG). There are three CWS plants onboard the T23 Ships deploying to either tasking can expect a which are designed to work in a maximum 6 month tour of which at least 4 months will seawater temperature of 30 oC (3). In extreme be spent in the regions described above, tropical conditions, defined as a seawater encompassing either summer or winter. Whilst temperature of >33 oC, the CWS does not cope winter in the Gulf is more bearable with well, and may result in machinery and temperatures averaging 20 oC, this paper will equipment failures, in addition to raising the examine exposure during the summer months background temperature of the habitable areas. where ambient temperatures can climb to Whilst in the Gulf, HMS SOMERSET 50 oC in the NAG (1) and approximately 40 oC in experienced an average daily seawater the SAG, along with high levels of humidity. temperature of 34-35 oC. This lead to not only Furthermore sea surface temperatures of an increased background heat of the living around 32-34 oC can increase the strain on spaces, but extreme heat in the specific areas ships’ machinery to breaking point whilst as shown in Table 1. Furthermore a lot of deployed in these Gulf zones. weapons engineering (WE) equipment contain internal sensors which alarm when they exceed Type 23 Frigates the recommended working temperature of The Type 23 frigate (T23) was designed to fight 30 oC, as occurred throughout the majority of in anti-submarine warfare during the throes of the tour

Location (inc. Location Marker) Maximum Ambient Air Temperature (if recorded) Main machinery spaces (CW Plant Room 4E, 50-58 oC Fwd AMR 4F, GTR 4G, MGR 4H, UAMR 1H, AvCat Pump Space 4K, Tiller Flat 3N) Hangar 1K 50 oC Galley 2F - 3J (Ship’s Office, overflow living space, offices) 38 oC Winch Well (onboard gym) 2M 48 oC Laundry 2L - Buffer’s Shack 2M-P 45 oC Quarterdeck 2N 40 oC Upper Deck / Seaboats 44 oC

Table 1 – Examples of hot spaces within a Type 23 frigate (11). 152 J Royal Naval Medical Service 2010, Vol 96.3

These are just a few examples of hot spaces protection from UV radiation. Finally the upper within the ship, where the above readings were deck gun crews, seaman specialists and not occasional, but consistently measured on a boarding teams including whose day to day basis, particularly during the months activities include boarding operations, seaboat of July and August. The strain placed on the transfers and providing force protection at sea CWS resulted in several failures of the system, or alongside, were exposed to heat and sun for leading to a catastrophic rise in inboard prolonged durations, all whilst wearing body temperatures, the subsequent failure of armour, lifejackets and combat dress with numerous electrical and weapon systems, and headgear and weapons both during exercises the near incapacitation of the entire ship’s and live operations. company due to extreme heat, saved only by Physical training is widely encouraged to the actions of the Marine Engineering (ME) maintain fitness, but is also actively pursued by department. Amazingly, no members of the many to release the pressure of working long Ship’s Company developed heat illness, stretches of defence watches whilst deployed in probably due to the mitigation employed. theatre. Personnel take part either in organised By comparison, the CWS onboard a Type exercise such as upper deck circuit training, or 22 frigate (T22) manages better in these personal training such as running around the extreme conditions. This is due to the fact that, upper deck or exercising in the gym which is as a larger ship, the T22 operates with five situated in the winch well. This area remained at CWS plants compared to the three onboard a a constantly high temperature during the day, T23 and thus is able to further compensate for falling only to around 40 oC during the night high seawater temperatures. (whilst in theatre in the summer months).

Exposure Risk of Heat Illness The Ship’s Company onboard a T23 are exposed The risk of heat illness comes mainly from to thermal stress under two main categories – exposure as outlined above, however there are the environment, and that produced by physical several other contributing factors which can be work or exercise, or a combination of both. predicted (3): Environmental conditions exert influence on the effectiveness of the body’s thermal cooling → Poor hydration systems. Conditions such as high environmental → Tiredness temperatures and high humidity, particularly in → Alcohol (or heavy indulgence the night combination with physical activity and military before) clothing are known to increase the risks of → Poor acclimatisation or new into theatre thermal stress and exertion associated → Workload heatstroke (12). ME department personnel → Poor nutrition spent a large amount of a watch in the main → Obesity machinery spaces, particularly during routine → Poor Aerobic fitness (13) maintenance and machinery breakdowns. Aircrew and aircrew engineers laboured for Individuals with a high aerobic fitness will both hours either in the Lynx or in the acclimatise faster than those who are less fit, hangar, both of which had continuously high and have a higher capacity for physical work; temperatures day and night. Chefs and other this advantage confers almost no improvement logisticians spent the duration of their watches when combining protective clothing and in the galley area without respite from the working in heat (14), necessitating strategies temperatures they were exposed to. Upper to reduce risk. deck maintainers spent large amounts of time Risk identification provides one of the most not only exposed to high ambient heat, but also important tasks for the onboard medical team exposed to additional solar radiation who should provide regular health briefs to the necessitating a further requirement for Ship’s Company. It is important that everyone Managing the risk of heat illness on board Type 23 frigates 153

Heat Exhaustion (Signs & Symptoms) Heat Stroke (Signs & Symptoms) Core temp <40oC Same as for heat exhaustion plus: CNS disturbance

Tiredness / weakness Core temp usually >40oC Dizziness Confusion Headache Irritability Palpitations Fitting Nausea & vomiting Coma Sweating Tachycardia Cramps Hypotension Pilo-erection Rising core temperature

Table 2 – Signs & Symptoms of Heat Illness adapted from Greaves, I., Porter, K. Oxford Handbook of Pre-Hospital Care (1st Edition) 2009 (15)

from junior rating to Commanding Officer is only account for temperature readings using aware of both the risks, and the signs and Wet Bulb Globe Thermometer (WBGT) ranges symptoms of heat illness. Heat illness is up to a WBGT index of 32 oC. Ambient air divided into two broader categories – heat temperatures were monitored regularly across exhaustion and heat stroke. Heat exhaustion the ship with dry bulb mercury thermometers by definition is where a patient’s core as opposed to WBGT. Although the WBGT temperature (rectal) is less than 40 oC, with measurement is more accurate as an indicator symptoms as seen in the table below, usually of thermal stress (because it also takes into following exposure to heat over long periods or account the effects of radiant heat, humidity following short periods of overexertion (15). and air velocity) it was not a readily available Heat stroke is a more severe condition, with a method onboard. Furthermore, due to the combination of central nervous system (CNS) nature of their work, many of the Ship’s impairment usually with core temperature Company found themselves spending hours at (rectal) recorded at greater than 40 oC and a time in their respective work areas, and were symptoms as outlined again in Table 2. unable to spend time in a cool environment Medical Officers are advised to brief Ship’s following such exposure as most if not all Company thoroughly on the above in order to compartments were subject to similarly hot teach recognition of heat illness. This increases ambient temperatures. vigilance towards problems developing, allows Preventative strategies (17,18) can be early identification of significant thermal strain in adapted for those working onboard the T23 who personnel where those affected may not notice are exposed to heat extremes where regular appearance of symptom, and helps prevent the breaks for cooling may not be feasible towards onset of illness or injury. Further first aid advice the nature of the job at hand, e.g. aircrew and medical management guidelines can be engineers working on the Lynx helicopter. found in JSP 539 (3), and in the published Advice sought from the Institute of Naval educational guides for climatic injury (16). Medicine lead to the following cooling methods being employed onboard HMS SOMERSET (19): Cooling • Roll sleeves up, immerse both arms up Guidance for risk assessment and safe to the elbows in a bucket of cool water duration of activities at various temperatures (~15oC) for 10-15 minutes every hour or can be found in JSP 539 (3), however these as close to this as is realistically 154 J Royal Naval Medical Service 2010, Vol 96.3

workable (20) working in the main machinery spaces • When time permits, remove clothes, and other isolated parts of the Ship, place subject in front of a fan and cool raising any potential health issues with with water spraying (18) supervisors as soon as possible • When time permits, subject to leave the hot work environment and spend time in An interesting point to note is background a cooler part of the ship, removing temperature. Where personnel who have served clothes to comfort in Iraq or Afghanistan have returned home for Should any cases of heat illness arise, Medical two weeks rest and recuperation, this has had a teams should respond in the normal manner, hugely detrimental effect on their acclimatisation with a ABCDE approach in accordance to the hot environment (23). In much the same with recognised emergency guidelines way, personnel onboard ships with efficient air (3,21,22) and employ the relevant methods of conditioning may find it harder to acclimatise, or monitoring (rectal temperature) and treatment may be more prone to suffering with heat (stripping patient, cooling with water spray in illness, whereas those onboard a T23 will be front of a fan, oral rehydration with water or living in a higher background temperature electrolyte drink) and consider onward referral throughout their deployment. This is perhaps one if appropriate, ensuring case reporting to INM positive point of the discomforts felt in many of Envionmental Medicine Unit takes place (3) via the habitable spaces. forms as at annex A. Suggested further work that should be undertaken in this area includes ships deploying Conclusion – Minimising Risk of Heat to hot climates sourcing WBGT monitors which Illness on a T23 are available as a NATO Stock Numbered item. With the risks of heat illness onboard a T23 These should be placed in the areas described now identifiable, the next step is to reduce the above, and regular recordings made to compile risk in a way which is practical to maintain a list of WBGT index ranges throughout the throughout the deployment. After guidance deployment. This would allow accurate from INM (19), the medical team from HMS exposure times of the crew to be calculated, SOMERSET advised the following simple steps and should exposure times be exceeded to ensure risks were not only minimised, but regularly, prompt change required to lower the also flagged up should they arise: risk to the health of the ship’s company. It is clear from the points explored in this → Remain well hydrated (drinking approx paper that the risk of heat injury is significant 1L/hr of WATER whilst in a hot space) with the T23 ships deploying to the Gulf. → Add a pinch of extra salt to food to Minimising this risk is the key part in ensure body salinity is maintained and to prevention of heat illness, and this falls avoid dilutional hyponatraemia (21) primarily under the responsibility of the → If time permits, leave workspace, strip Medical Department. Education of personnel is off overalls and use fan and water spray invaluable, as it encourages propagation of the for cooling measures put in place as discussed above. → If time does not permit, immerse bare Following a series of heat illness and health arms to the elbows in a bucket of cool briefs onboard HMS SOMERSET, leaflets were water for 10-15 minutes to allow placed in each of the mess decks as at Annex increased sustainability for work B, and Ship’s Company were encouraged to → Observe urine (cloudy, yellow and bring questions about heat illness to the infrequent suggests poor hydration) sickbay at any opportunity. Following all these → Observe each other – “buddy-buddy” measures, HMS SOMERSET came through vigilance practiced with Ship’s Company the OP TELIC summer 2010 tour with no cases looking out for each other, particularly of heat illness, despite the arduous conditions whilst exercising in the winch well, or experienced by those serving onboard. Managing the risk of heat illness on board Type 23 frigates 155

Annex A – Heat Illness reporting form as per JSP 539

Reference (if applicable) Ship/Unit/Station Sub Unit

CASUALTY DETAILS Personal Name Initials Number Rank/ Regt/Corps/ DOB Rate Trade

INCIDENT DETAILS Date of Incident Time (Local)

Location

Activity

Clothing Worn

Equipment and Weight Carried WBGT Index Reading

CLINICAL DETAILS Casualty Temp Where was Rectal / Axilla Time temp Hrs temp taken? / Oral / TM* was taken Signs and Symptoms Pulse: B/P: Diagnosis

Other Clinical BM: Measurements O2 Sats: Subsequent Action (Cooling, IVI and so on.) Disposal (for example. Admit MRS / Hosp and so on.)

PREDISPOSING FACTORS Unacclimatised Yes / No / NA* Unfit Yes / No / NA* Alcohol Yes / No / NA* Sleep Deprivation Yes / No / NA* Dehydrating Illness Yes / No / NA* Respiratory Infection or Yes / No / NA* Febrile Illness Failure to Replace Fluid Yes / No / NA* Medication / Drugs Yes / No / NA* Loss Previous Heat Illness Yes / No / NA* Obesity (State BMI if a Yes / No / NA* contributory factor) BMI: Other Relevant Factors for example, equipment

*Delete those not applicable (NA = Not Applicable) Continue overleaf if more space required.

Name of Medical Officer:……………...……Signature:………….….………Date:……….…

156 J Royal Naval Medical Service 2010, Vol 96.3

Annex B – Heat Stress Prevention Leaflet for Ship’s Coy on HMS SOMERSET Heat Stress Prevention

During this deployment, many ship’s company will undergo prolonged exposure to temperatures ranging between 30 and 55 degrees centigrade. This carries with it a risk of developing heat illness, so what can you do about it to minimise that risk? Average working times on land would be 45 minutes on, 15 minutes off in a cool environment to allow body temperature cooling. Obviously that cannot always be achieved in the working environment onboard a ship, so here are a few tips to help you if you are exposed to high temperatures on a daily basis: → Aim to drink 1 L water per hour – you can measure if you are well hydrated by the frequency and colour of your urine, going regularly, and paler & clearer in colour is better!! → Add a pinch of salt to your meals – this helps keep your body sodium levels normal and prevents dilution from all that water you are drinking → For every hour of work in a hot part of the ship, take 10 minutes to roll your sleeves up, and place your arms up to the elbows in a bucket of cool water (approx 15 degrees, doesn’t need to be ice cold!) and gently stir them around. 10 minutes can help lower your core body temperature (and you don’t even need to take your overalls off!) Remember, heat stress can cause serious problems. Simple measures can stop those serious problems from developing!

Any questions or concerns, contact the Sickbay

Medical Officer

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9. Ramsey, J. et al., (1983). Effects of workplace of heat strain by immersing hands and foreams in thermal conditions on safe work behaviour . J water . J R Navy Med Serv 83 (1): 26-30 Safety Res. 14:105-114. 18. House JR, Lunt H, Magness A, Lyons J (2003) 10. S2022A No 720248/1 – T23 CW Plant & CW Testing the effectiveness of techniques for System Ops in extreme tropical conditions 9 Jun reducing heat strain in nuclear, 2004 biological and chemical cleansing station’s teams . 11. Unpublished data – Dry temperature readings J R Navy Med Serv 89(1):27-34 recorded by various departments on HMS 19. Verbal advice from Dr Dan Roiz de Sa, Survival SOMERSET Jul 2010 and Thermal Medicine, Environmental Medicine 12. Montain SJ et al. 1994. Physiological tolerance and Sciences. Institute of Naval Medicine, to uncompensable heat stress: effects of Gosport, UK – Jul 2010 exercise intensity, protective clothing, and 20. INM Report No.2003.003 – Proposals for climate . J Appl Physiol. 77(1): 216-222. reducing heat strain in Ships’ NBC cleansing 13. Armstrong LE, DeLuca JP, Hubbard RW (1990) stations – Feb 2003 Time course of recovery and heat acclimation 21. JSP 570 Battle Field Advanced Trauma Life ability of prior exertional heatstroke patients . Med Support 4th Edition 2008 Sci Sport Exerc 22:36-48 22. Clinical Guidelines for Operations . Joint Doctrine 14. Aoyagi Y, McLellan TM, Shephard RJ (1994) Publication 4-03.1. ist Edition September 2008. Effects of training and acclimation on heat Ministry of Defence. tolerance in exercising men wearing protective 23. INM Report No.2009.005 – Evidence-base clothing . Eur J Appl Physiol (68): 234-245 informing current MOD policy to mitigate risk of 15. Greaves, I., Porter, K. Oxford Handbook of Pre- heat illness and manage heat injury: An update of Hospital Care (1st Edition) 2009 the INM’s research programme – Jan 2009 16. Don’t be Your Own Worst Enemy - Climatic Injuries: Heat and Cold – Protect Yourself. Annexes Defence Health Promotion Educational DVD A. Heat Illness reporting form – JSP 539 Climatic package C5196/10. British Defence Film Library. Injuries in the Armed Forces: Prevention and Published with accompanying Individual and Treatment 2003 Commander’s Guides. B. Heat Stress Prevention Leaflet for Ship’s Coy on 17. House JR, Holmes c, Allsopp AJ (1997) Prevention HMS SOMERSET – Surg Lt T Stevenson July 2010

Surg Lt Tom Stevenson RN, MO HMS SOMERSET

Dr Dan Roiz de Sa, CMO Environmental Medicine and Sciences. Institute of Naval Medicine.