Heat stroke and preventive measures

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Every summer, the hazards caused by high temperatures become the most significant factor threatening the health of those who work in hot conditions, and heat stroke is attracting increasing attention. I. What is work in high-temperature conditions? Work in high-temperature conditions refers to work carried out under abnormal weather conditions characterized by high temperatures, intense heat radiation, or high humidity (relative humidity ≥ 80% RH), where the wet-bulb globe temperature index (WBGT index) exceeds the specified limits. Hot weather refers to conditions in which the daily maximum temperature exceeds 35°C, as reported to the public by the meteorological stations under the meteorological authorities at the prefecture level or above. The temperature is subject to the readings issued by the meteorological stations under the meteorological authorities at the prefecture level or above. Working in high-temperature conditions refers to the situation where an employer assigns workers to carry out tasks in an environment with high natural temperatures during such periods. II. What are the main effects of working in high-temperature environments on the human body? The working capacity of workers in high-temperature environments declines significantly as the temperature rises. Research indicates that when the environmental temperature reaches 28 degrees, a person’s reaction speed, cognitive ability, sensory sensitivity, and motor coordination all decline significantly. In addition to causing heat exhaustion in workers, working in high temperatures can also have the following effects on human health: ① Disruption of water and salt metabolism: In a hot and humid environment, excessive sweating leads to disruptions in water and salt metabolism, increasing the risk of heat cramps ； ②Circulatory system: When engaging in physical labor in high-temperature environments, the heart must pump large amounts of blood to the highly dilated blood vessels in the skin in order to dissipate heat effectively ； It is also necessary to supply sufficient blood to the working muscles to ensure their function, as well as to maintain an appropriate blood pressure. On the other hand, effective blood volume decreases due to the loss of large amounts of water through sweating and the shift of body fluids to the muscles. This supply-demand imbalance puts the circulatory system under high stress. The heart’s ability to pump blood to the periphery depends on cardiac output, which in turn depends on the maximum heart rate and vascular blood volume. If heat workers reach their maximum heart rate during work, and the body’s heat storage continues to increase, cardiac output can no longer increase to maintain blood pressure and muscle perfusion, which may lead to heat exhaustion. ③Digestive system: During work in high temperatures, the secretion of digestive juices decreases, and the activity of digestive enzymes as well as the acidity of gastric juice (free acid and total acid) decline. The contraction and peristalsis of the gastrointestinal tract are reduced, slowing down the rates of absorption and emptying. Salivary secretion is significantly reduced, and amylase activity is decreased. Added to this is the reduced blood flow in the digestive tract, with excessive water intake diluting stomach acid. These factors can all cause loss of appetite and indigestion, as well as an increase in gastrointestinal disorders. Moreover, the longer the length of service, the higher the prevalence rate. ④Nervous system: Depression of the central nervous system, reduced muscle activity, decreased accuracy of movements ； ⑤Urinary system: Excessive sweating, decreased renal blood flow and glomerular filtration rate, blood concentration leading to increased renal load, which results in renal insufficiency and other conditions. III. What is heatstroke? Heatstroke is an acute heat-induced disease that occurs in high-temperature environments, caused by disruptions in heat balance or water and salt metabolism, and characterized primarily by disorders of the central nervous system and/or cardiovascular system. The main causes of heatstroke include: excessively high ambient temperatures and high humidity ； Excessive workload and long duration ； Excessive fatigue, lack of sleep ； Lack of heat acclimatization, physical weakness, etc. Based on the occupational history of workers exposed to high temperatures, as well as clinical symptoms such as elevated body temperature, muscle cramps, and syncope, and by ruling out the influence of other diseases, occupational heat stroke can be diagnosed. In cases of mild heat stroke, workers experience ① dizziness, chest tightness, palpitations, flushed face, and hot skin ； ②Early symptoms of respiratory and circulatory failure, such as excessive sweating, pale complexion, low blood pressure, and weak pulse ； ③Clinical symptoms such as a rectal temperature rising above 38.5°C. Severe heat stroke can be diagnosed whenever one of the main clinical symptoms of heatstroke, heat cramps, or heat exhaustion is present. Heat stroke: It occurs in hot environments when the mechanisms for heat dissipation are impaired, leading to an imbalance in body temperature regulation. The clinical features include sudden onset, with a body temperature that can rise above 40°C. Initially, there is excessive sweating, followed by an absence of sweat, along with symptoms of the central nervous system such as dry heat, disturbance in consciousness, drowsiness, and coma. The mortality rate is very high. Heat cramps: Caused by excessive sweating, which leads to a loss of excessive amounts of sodium and potassium in the body. The clinical manifestations are mainly muscle spasms, accompanied by contracting pain. Spasms occur most frequently in muscles that are used frequently, such as the muscles of the limbs and abdominal muscles, with the gastrocnemius being the most affected. The spasms are symmetric, occurring intermittently with periods of remission; the patient is conscious and has a normal body temperature. Heat exhaustion: In high-temperature and high-humidity environments, an increase in skin blood flow occurs without constriction of the vascular vessels in the internal organs or an increase in blood volume; insufficient compensation leads to a temporary reduction in blood supply to the brain, resulting in fainting. The onset is usually rapid, with initial symptoms including dizziness, headache, palpitations, sweating, nausea, vomiting, cold and damp skin, pale complexion, a temporary drop in blood pressure, and fainting. Body temperature is slightly high or normal. A short rest will help restore consciousness. 4. Treatment of heat stroke: For mild heat stroke, the patient should be quickly moved away from the hot environment to a well-ventilated area to rest; salty, cooling beverages should be given, and intravenous infusion of glucose saline may be necessary if required. Severe heatstroke: Heat stroke: Lower body temperature, maintain the function of the circulatory and respiratory systems, and correct disorders in water and electrolyte balance. Heat cramps: Oral administration of salt-containing cooling beverages; intravenous infusion of glucose saline if necessary. Heat exhaustion: Move to a well-ventilated and cool place, give oral saline drinks, and provide symptomatic treatment. V. Measures for heat prevention and cooling in high-temperature work environments 1. Technical measures: Reasonably design the production process, and improve production equipment and operating methods. Arrange the heat sources reasonably, trying to place them outside the workshop as much as possible ； In natural ventilation based primarily on hot air pressure, it is located beneath the skylight ； In natural ventilation driven primarily by cross-ventilation, it is placed on the downwind side of the prevailing wind in summer ； Insulation measures are taken for the heat source ； The workplace is easy to cool down, etc. Use water or materials with a low thermal conductivity for insulation. Use natural ventilation and mechanical ventilation to improve air circulation and reduce temperature; install air conditioning systems in places where conditions permit. 2. Health measures: ① Provide workers engaged in high-temperature tasks with salty beverages and nutritional supplements; each person should consume 3–5 liters of such beverages per day, with the salt content in the beverages being between 0.15% and 0.2%. ②Strengthen individual protection by equipping workers performing tasks in high-temperature environments with heat-resistant clothing, protective goggles, face shields, gloves, shoe covers, leg guards, and other protective gear. For workers engaged in high-temperature tasks with high radiation levels, flame-resistant white work uniforms with a low thermal conductivity should be provided. For short periods of work in high-temperature environments, an ice vest can be worn (such as by firefighters). ③Strengthen medical preventive measures by conducting physical examinations for workers engaged in high-temperature tasks before they start working and before the hot season begins, in order to identify any occupational contraindications. ④Organizational measures: strengthen leadership, improve management, and strictly adhere to **high-temperature work standards**. During the hot season, it is necessary to adjust work schedules appropriately and implement shift rotation to ensure that workers performing tasks in high temperatures have sufficient sleep and rest during the summer.