In meteorology, a day with a maximum temperature of ≥ 35℃ is generally referred to as a high-temperature day. In the field of occupational health, high-temperature work refers to work where the average Wet Bulb Globe Temperature (WBGT) index at the workplace is ≥ 25℃ during production and labor processes. The Wet Bulb Globe Temperature (WBGT) is a comprehensive measurement index for evaluating the heat load on the human body, which integrates the effects of high air temperature, thermal radiation, and air humidity on the human body, with the unit also being Celsius (℃).
Types of High-Temperature Work
Dry-heat work: Characterized by high air temperature, strong thermal radiation, and low relative humidity, such as work in furnaces, kilns, and hot metal processing.
Humid-heat work: Characterized by high air temperature and high humidity, but low thermal radiation, such as work in textile mills, printing and dyeing factories, and underground mines.
Open-air work in summer: Work conducted in high-temperature natural weather conditions, such as construction, courier services, food delivery, and environmental sanitation
How to Prevent Heatstroke During High-Temperature Work
Pay close attention to weather forecasts
For work with adjustable schedules, appropriately adjust the working hours to avoid working or engaging in outdoor activities during peak high-temperature periods as much as possible. For groups like food delivery riders who find it difficult to adjust their working hours, take personal protective measures when going out—such as wearing sun-protective clothing and sun hats to prevent direct sunlight on the skin. Additionally, carry heatstroke prevention medications like Huoxiang Zhengqi Shui (a traditional Chinese medicine for relieving summer heat-related discomfort) for emergency use.
Replenish water and electrolytes in a timely manner
Drink more light salt water and cool beverages containing electrolytes, and reduce intake of sugary or carbonated drinks.
Pay attention to diet and daily routine
Usually, focus on a light and easy-to-digest diet, and eat more fresh vegetables and fruits with high water content. At the same time, try to maintain adequate sleep every day and avoid staying up late for a long time—this helps the body relax and prevents health risks such as heatstroke. After working continuously for a period of time, take appropriate rest based on your physical condition to relieve fatigue; this not only improves work efficiency but also helps ensure safe production.
Monitor your own health status
Workers with diseases such as cardiovascular, pulmonary, or cerebrovascular diseases, tuberculosis, central nervous system diseases, as well as those unfit for high-temperature work, should avoid engaging in open-air high-temperature work to prevent accidents.
How to Identify Heatstroke?
Heatstroke typically progresses gradually from mild to severe. When working or engaging in activities in a high-temperature environment, if you experience dizziness, headache, fatigue, thirst, or flushing of the face, you should be alert—these may be premonitory symptoms of heatstroke.
If you experience short, intermittent muscle spasms (commonly known as “cramps”), this may be heat cramps caused by sodium loss. Heat cramps usually occur in people who are new to working in high-temperature environments, engage in excessive physical activity, sweat heavily, and only replenish water (without replacing electrolytes).
If you have symptoms such as profuse sweating, cold and clammy skin, pale complexion, or a significantly accelerated heart rate, this may be heat exhaustion caused by excessive loss of body fluids and sodium.
If heat exhaustion is not treated promptly, it may develop into heatstroke (heat stroke), the most severe form of heat-related illness. Typical symptoms of heat stroke include sudden high fever, dry and hot skin, and varying degrees of disturbed consciousness; in severe cases, it may even cause multi-organ dysfunction.
First Aid for Heatstroke
If you experience premonitory symptoms of heatstroke (such as headache or dizziness) while working or engaging in outdoor activities in hot weather, move to a cool place to rest and replenish water as soon as possible. If symptoms are severe and you cannot move independently, seek help from others immediately.
In case of muscle spasms, in addition to the above measures, appropriately replenish beverages containing salt or electrolytes (e.g., beverages with sodium, potassium, or magnesium). If discomfort persists or worsens, seek medical attention promptly. If symptoms such as burning skin, confusion, slurred speech, or even coma occur, seek medical help immediately.
Prolonged work in a strong heat environment can harm workers’ health, reduce productivity, and even cause work accidents. Therefore, both national and international occupational health standards have clear regulations on the evaluation of high-temperature environments, with the WBGT index serving as the evaluation indicator.
Typical High-Temperature Work Environments
High-temperature and strong thermal radiation environments: Coking, iron-smelting, and steel-making workshops in the metallurgical industry; foundry workshops in the machinery manufacturing industry; furnace and kiln workshops in the ceramic, glass, and building materials industries.
High-temperature and high-humidity environments: Textile and printing and dyeing factories, deep coal mines.
Open-air work in summer: Construction sites, large-scale sports competitions, etc.
Views of the World Health Organization (WHO)
When working in a hot environment, the risk of heat-induced illnesses (including heat exhaustion, heat stroke, and heat syncope) increases when the worker’s internal body temperature exceeds 38℃.
What is the WBGT Value?
The WBGT (Wet Bulb Globe Temperature) index, also known as the wet bulb globe temperature, is a basic parameter for comprehensively evaluating the heat load on the human body in the work environment, with the unit of ℃. The WBGT index is composed of three temperature components: the natural wet bulb temperature (Tnw), the globe temperature (Tg), and the dry bulb air temperature (Ta) (measured additionally in open-air conditions). It comprehensively considers four factors: air temperature, wind speed, air humidity, and thermal radiation.
This method can be conveniently applied in industrial environments to evaluate the heat intensity of the environment. It is used to assess the heat intensity that the human body endures throughout the work cycle, but is not suitable for evaluating heat intensity in short periods or near the thermal comfort zone.
Calculation Formula for WBGT Index
Indoor or outdoor without solar radiation: WBGT = 0.7 Tnw + 0.3 Tg
Outdoor with solar radiation: WBGT = 0.7 Tnw + 0.2 Tg + 0.1 Ta
The JT2011 and JT2013 are high-precision heat index testing instruments independently developed by “Jiantong Technology“. They can simultaneously measure air temperature, wet bulb temperature, and radiant temperature. These testers adopt advanced digital temperature sensors as temperature collection terminals and are equipped with standard 50mm and 150mm radiant globe thermometers independently developed by the company. They comply with ISO standards and relevant national standards and can pass verification by the National Institute of Metrology.
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