BASIC PRINCIPLES IN OCCUPATIONAL HYGIENE Day 4 4

BASIC PRINCIPLES IN OCCUPATIONAL HYGIENE 职业卫生基本原则 Day 4 第 4天

15 - THERMAL ENVIROMENT 15 -热环境

THERMAL ENVIROMENT 热环境 • In order to function effectively we need to maintain our bodies at a constant temperature within 36. 5 - 37. 5 o. C. • 为了能让身体正常运行，我们需要确保体温恒定在 36. 5 - 37. 5℃。 • Temperature regulation centres in our brain are sensitive to small changes of blood temperature and also get feed back from sensory nerves at the skin. • 我们的大脑是一个温度调节中心，对体温的微小变化都很敏感，还能获得皮肤感觉神经的反馈。 • Our brains then use this information to adjust our bodies responses to heat. • 我们的大脑会根据反馈的信息调节身体，适应热环境。

HEAT 高温 Physiological responses to heat 对高温的生理反应 – Blood vessels in skin expand 皮肤血管扩张 – Pulse rate increases 脉搏加快 – Increases blood to the surface of the body 体表血液增加 – Sweating also increases heat loss due to latent heat of evaporation. – 出汗也会散热，因为汗液会蒸发。 – In very hot conditions, sweating offers greatest potential for regulating body temperature. – 如酷热环境，出汗是调节体温的最有效方式。 Possible adverse effects of exposure to excessive heat include; 接触高温可能的副作用包括： – Fatigue 疲劳 – Behavioural modification 行为变化 – Reduced concentration 集中度不高 – Heat cramps due to salt loss 因体内盐分减少，可能出现中暑性痉挛。 – Fainting heat exhaustion 中暑昏厥 – Heat stroke 中暑

COLD 低温 Physiological responses to cold 对高温的生理反应 – Blood vessels in skin contract – 皮肤中血管紧缩 – Heat flow to the body surface is reduced – 皮肤表面热流减少 – Heat production is increased by physical activity and shivering. – 因活动和发抖会增加产热 – No physiological acclimatisation to cold – 生理水土不服 Possible adverse effects to excessive cold include; 接触低温可能的副作用包括： – lassitude/listlessness, – 精神不振/萎靡 – chilblains, – 冻疮 – frost bite – 冻伤 – hypothermia. – 低体温

Psychological Responses to the Thermal Environment 对热环境的心理反应 • People will often modify the way they work depending on thermal environment. • 人们会根据热环境条件改变其作方式 • Modify their local work environment • 调节其作环境 – moving to a more comfortable area, – 转移到更加舒适的区域 – changing clothes, – 换衣服 – increasing or decreasing ventilation – 增加或减少通气量 • Performance and efficiency can also be affected by adverse thermal conditions. • 热环境不当可能会影响绩效和效率。

Heat Transfer from the Body 体内传热 Six parameters that may be taken into account: 应考虑如下六个参数： S=M‑W+C+R+K‑E Where: 其中： S M W C R K E = = = = Storage, which in the long term must equal 0 Metabolism External work done Convection Radiation Conduction Evaporation 存储，如长期存储，则该数值为零代谢完成的对外作对流辐射传导蒸发

Factors Influencing Heat Balance 影响热平衡的因素 1 Work rate (i. e. activity or metabolic rate) 作率（即活动或代谢率） 2 Clothing 服装 3 Air temperature 空气温度 4 Radiant temperature 辐射温度 5 Air Velocity 空气流速 6 Humidity (moisture) conditions 湿度（水分）条件 Person 人 Environment 环境

Metabolic Rate 代谢率 Activity 活动 Metabolic Rate (W/m 2 body surface) 代谢率（ W/m 2体表） Sleeping 睡觉 43 Resting 休息 47 Sitting 坐 60 Standing 站 70 Slow Walk (2. 5 kph) 慢走(2. 5 kph) 107 Walking (5 kph) 正常走(5 kph) 154 Running ( 16 kph) 跑步（16 kph) 600 Sprinting (25 kph) 短跑 (25 kph) 2370

Personal Insulation 防烫伤隔热 Clothing 服装 Clo Value 克罗值 Naked 裸体 0 Shorts 穿短袖 0. 1 Light summer clothes 穿夏装 0. 5 Typical indoor clothes 穿家居服 1. 0 Heavy suit 穿厚外套 1. 5 Polar clothing 穿极地服装 3 -4 Practical maximum 穿很多衣服（实际最大量） 5

THERMAL ENVIROMENT 热环境 • • Dry Bulb Temperature 干球温度 Mean Radiant Temperature 平均辐射热 Air Velocity 空气流速 Personal monitoring. 个人监测

Heat Stress Indices 热应力指数 Various workers have devised indices to combine some of them into a single figure to which a standard could be applied. Some of these include: 各类人都已制定了指数，即，可以将其与标准应用环境相互融合的指数。其中包括： – Wet Bulb Globe Temperature: A simple index calculated after measuring the dry bulb, natural wet bulb and globe temperatures. – 暑热压力指数：测量干球、自然湿球和黑球温度后计算的简单指数。 – – HSI (Heat Stress Index): Calculated using a range of environmental measurements as well as work rate. HSI（热应力指数）：使用各类环境测量数值和作速率计算的指数。 P 4 SR (Predicted Four Hour Sweat Rate): Calculated from charts and used to assess physiological limits. P 4 SR（预测4小时出汗率）：根据图表计算的指数，用于评估生理极限。

Thermal Comfort 热舒适 • Very subjective and people will feel differently about what is the ‘ideal’ thermal environment. • 热舒适因人而异，非常主观，不同的人对理想的热环境有不同的感觉。 • Much less extreme conditions than thermal stress. • 极端条件比热应力少很多。 • Indices have also been generated in an attempt to measure thermal comfort. • 在尝试测量热舒适时产生的指数。