Hong Kong sweltered in the heat during three consecutive days of dangerously hot weather last week, with at least 14 people rushed to hospitals for heat stroke. Among them was a 19-year-old hiker who was sent to the emergency room in a critical condition. Hong Kong can expect to see more searing days and night for the rest of the summer, as it is on track to break more hot weather records this year. Last year saw the most number of “very hot weather” warnings issued since records began. Extreme weather patterns and global warming will also affect the temperature, and may possibly increase the risk of heat stroke. Hot summer nights could be bigger killers than daytime scorchers While the city’s Hospital Authority and Department of Health do not report a yearly tally of heat stroke cases, doctors warn that they are no joking matter. In 2009, there were about 100 in-patient discharges, including two patient deaths, in public and private hospitals, which were attributed to heat-related illnesses. Here are what you need to know about heat-related illnesses, heat stroke and how you can prevent it. These generally refer to a range of disorders such as heat rash, heat cramps, heat syncope – dizziness or fainting – heat exhaustion, and in the most serious form of heat illness, heat stroke. Symptoms begin to manifest when a person’s core body temperature rises above the normal range of 36 to 38 degrees Celsius. How serious is heat stroke? Can it be fatal? Heat stroke is a life-threatening condition requiring immediate medical attention. It is the developed stage of heat exhaustion, which is mainly caused by dehydration or electrolyte depletion in hot weather. Symptoms of heat stroke kick in when core body temperatures rise to more than 40 deg C. The skin will start to turn red, and feel hot and dry; the tongue will feel swollen, and breathing becomes increasingly difficult and the pulse will also speed up. Sufferers will start to feel a headache, nausea and may even feel dazed and disoriented. If nothing is done to lower the body temperature, the person could suffer a seizure or fall into a coma. According to the Centre for Health Protection, the probability of dying from a heat stroke depends on its severity and the age of the patient, with the mortality rate varying widely from 10 per cent to 70 per cent. The overall case fatality rate worldwide is about 12 per cent. What groups are vulnerable to heat stroke? The elderly, those who are overweight or obese, and those suffering from chronic diseases are especially vulnerable as their bodies have a reduced ability to regulate their core temperature. Those who rely on others to care for them, or help them hydrate, including babies, young children and those with disabilities, are also at risk. Another group susceptible to heat stroke is those who perform physical work outdoors or in hot places such as construction workers, firefighters and kitchen workers. People taking part in sports or other outdoor activities are also vulnerable. According to the US Centre for Disease Control and Prevention, heat illnesses are the number one causes of death among high school athletes in the United States. In Hong Kong, many hikers in the hot, humid summer months fall victim to heat illness. Are hot and humid days more dangerous? A 33 degree Celsius afternoon in subtropical Hong Kong can feel much hotter than in places with more temperate or oceanic climates. This is due to the city’s high humidity levels. “Humidity affects the evaporation of sweat, which is our bodies’ main [way of dissipating heat],” said Dr Lobo Louie Hung-tak, associate professor of physical education at Baptist University. “Because sweat is unable to evaporate fast enough, it envelops your skin and forms a blanket over it. This can quickly cause your body to overheat.” The heat sensation brought about by factors such as humidity and wind is known as heat stress. According to the Observatory’s Hong Kong Heat Index, which measures heat stress, a 33 degrees temperature with 85 per cent humidity will make a person’s body feel like the weather is 50 degrees. “The combination of physical stress and heat stress can elevate the risk of heat stroke,” said Dr Kenneth Wu Wing-cheung, chairman of the sports medicine committee at the College of Emergency Physicians. Would the weather be too hot to go for a hike during the Hong Kong summer? It is all about risk management, according to Dr Louie, who says that most injuries are a result of negligence and underestimating risks. He cited three levels of risk management in outdoor sports that people should be aware of. The first is the individual – the person himself or herself, age, fitness level and skill. The second level is about equipment. This includes whether or not the person has adequate water supply, the right backpack and appropriate footwear. The third is environmental factors, which include the weather and terrain of the route or trail. “All it takes is a simple risk assessment. Many young people like to take risks and do more challenging routes than they can handle just to take some nice pictures. Inexperienced hikers might decide to do Sharp Peak in the summer without understanding their own skill,” he said. Hiking injuries tend to occur more in large groups of hikers as there are bound to be some who cannot keep up with the pace of the group. “People must assess their own ability and understand their own body,” Dr Louie said. “Heat stroke could cause you to lose consciousness. In the outdoors, the risk is even greater as you could fall down a cliff and get trapped. Mountain rescues are very time-consuming.” What can I do to prevent heat stroke? The Centre for Health Protection urges people to take precautions during very hot weather. Such weather conditions is classified by the Observatory as when temperatures go above 33 degrees. The centre advises the public to: ● Wear loose and light-coloured clothing to reduce heat absorption and facilitate sweat evaporation and heat dissipation ● Avoid vigorous exercise and prolonged activities such as hiking or trekking as heat, sweating and exhaustion will place additional demands on your physical condition ● Perform outdoor activities in the morning or late afternoon ● open all windows, use a fan or use air-conditioning to maintain good ventilation for indoor activities ● Reschedule work to cooler times during the day. For those who are planning to head outdoors, they should try to avoid direct exposure to the sun, wear a hat and UV blocking sunglasses, and apply sunscreen with sun protection factor (SPF) of 15 or above, reapplying it liberally after sweating or swimming. People should also carry and drink plenty of water and rest at regular intervals to allow the body to cool down and recuperate. Surely an ice-cold beer after a hike would cool me down, right? Those engaged in strenuous outdoor activities should also stay clear of caffeinated drinks such as coffee or tea, as well as alcohol. This is because drinking such beverages causes a person to urinate more, thus speeding up dehydration. Though many enjoy having a beer or two after a long hike or workout, this could be unsafe, Dr Wu said. “Blood circulation won’t be that good, blood pressure could drop and lead to insufficient blood to the brain. This could lead to a syncope attack, which leads to collapse,” he said. “We strongly advise hikers not to have alcohol after exercise until they are fully hydrated.”