HYGIENE STANDARDS AND OCCUPATIONAL EXPOSURE LIMITS 卫生标准或职业接触限值

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1 HYGIENE STANDARDS AND OCCUPATIONAL EXPOSURE LIMITS 卫生标准或职业接触限值

2 Hygiene Standards or Occupational Exposure Limits (OELs) (1) 卫生标准或职业接触限值（OEL）
They are not an index of toxicity 不是毒性指数。 They do not represent a fine demarcation between good and bad practice. 不是良好规范和不良规范的分界。 They are based on the current best available information and are liable to change. 是根据当前最佳可用信息确定的，可能会有变更。 If there is not a hygiene standard set for a chemical substance, it does not mean that substance is safe. 如某化学物质没有卫生标准设定值，不表示该物质是安全的。 Good occupational hygiene practice is to keep airborne contaminants to as low a level as possible, not to just below the relevant hygiene standard(s). 良好的职业卫生规范是确保大气污染物尽量少，不应该只是低于相关的卫生标准。

3 Hygiene Standards or Occupational Exposure Limits (OELs) (2) 卫生标准或职业接触限值（OEL）
They apply to occupational exposure of adults. They are not applicable to environmental exposure where more susceptible groups exist e.g. pregnant women, children, infirm. OEL适用于成人的职业接触。 OEL不适用于存在易感人群的环境接触，如：孕妇、儿童、和体弱者。 For chemicals they generally relate to airborne concentrations i.e. they only take into account the inhalation route of entry. 对于与空气浓度相关的化学品，只考虑其吸入的侵入方式。 They generally refer to single substances, although some guidance may be given on mixed exposures. 仅指单个物质，虽然存在混合物的指南。

4 Setting of Hygiene Standards and Exposure Limits 卫生标准和接触限值规定
There are three main types of hygiene standards:- 目前有三种主要类型的卫生标准： Chemical agents such as gases, vapours, fumes, mists, dusts and aerosols. 化学因素：如气体、蒸汽、烟雾、迷雾、粉尘和气溶胶。 Physical agents such as noise, vibration, heat, cold and radiation (ionising and non‑ionising) 物理因素：如噪声、振动、热、冷和辐射（电离和非电离） Biological exposure indices. 生物接触指标。

5 Setting of Hygiene Standards and Exposure Limits 卫生标准和接触限值规定
When setting hygiene standards for hazardous agents, the effects the agents might have on the body have to be considered namely:- 设定有害因素的卫生标准时，应考虑各因素对人体的影响： Contact 接触 Local toxic effects at the site of contact (skin, eye, respiratory tract etc.) 接触部位的毒性（皮肤、眼、呼吸道等。） Absorption 吸收 Transport, Metabolism, Storage 运输、新陈代谢、存储 Systemic toxic effects, remote from the site of contact (any organ system e.g. blood, bone, nervous system, kidney etc.) 远离接触部位的全身毒副作用（任何器官系统，如血液，骨骼，神经系统，肾脏等） Excretion 排泄 Acute toxicity i.e. the adverse effects occur within a short time of exposure to a single dose, or to multiple doses over 24 hours or less e.g. irritation, asphyxiation, narcosis 急性中毒，即短时间接触单次量时发生的副作用，或24小时或更长时间接触多次量时发生的副作用，如刺激、窒息、昏迷； Chronic toxicity. 慢性毒性。

6 Setting of Hygiene Standards and Exposure Limits 卫生标准和接触限值规定
The data for setting hygiene standards includes the use of: 设置卫生标准的数据包括对如下信息的使用： Animal studies 动物研究 Human research and experience 人体试验和体验 Epidemiology (the statistical study of disease patterns in groups of individuals) 流行病学（对个人组病证进行统计研究） Analogy. 以此类推

7 Hygiene Standards for Chemical Agents 化学因数的卫生标准
Only a few countries have organisations with the appropriate resources for setting limits. Most countries base limits on the following: 仅有少数几个国家拥有设置限值所需的资源。大多数国家采用如下限值为基础。 Limit 限值 Country / Union国家/联盟 TLV – Threshold Limit Value阈限值 USA美国 MAK - Maximale Arbeitsplatz-Konzentration 最高容许浓度 Germany 德国 MAC Russia俄罗斯 WEL – Workplace Exposure Limit 工作场所接触限值 United Kingdom英国 IOELVs (Indicative Occupational Exposure Limit Value) （指示性职业接触限值） Europe欧洲 OES – Occupational Exposure Standards 职业接触标准 Australia澳大利亚 WES – Workplace Exposure Standards工作场所接触标准 New Zealand新西兰

8 Quantifying Airborne Concentrations of Chemical Agents 量化化学因素的大气污染物浓度
Airborne contaminants can be quantified in several ways; 可采用几种方式来量化大气污染物 By volume - atmospheric concentration in parts per million (ppm) 按体积——大气浓度/百万分之一（ppm） By weight - milligrams of substance per cubic metre of air (mg.m-3). 按重量——每立方米空气中物质重量（毫克）（ mg.m- 3 ）。

9 Milligrams per cubic metre (mg m-3) 毫克每立方米 (mg m-3)
mg = mg/m3 = mg m-3 m3

10 Quantifying Airborne Concentrations of Chemical Agents 量化化学因素的大气污染物浓度
There is a correlation between ppm and mg.m-3: ppm 和 mg.m-3的关系 Conc by weight (mg.m-3) = Conc by volume (ppm) x Molecular weight (g) 24.06 浓度/重量 (mg.m-3) = 浓度/体积 (ppm) x 分子重量 (g) 温度：20°C ，大气压 ： 760 mm Hg （1个大气压）

11 Quantifying Airborne Concentrations of Chemical Agents 量化化学因素的大气污染物浓度
Can you rearrange this equation to convert ppm to mg.m-3 ? 能用该公式将ppm转换成mg.m-3 吗？ Conc by weight (mg.m-3) = Conc by volume (ppm) x Molecular weight (g) 24.06 浓度/重量 (mg.m-3) = 浓度/体积 (ppm) x 分子重量 (g) Conc by volume (ppm) = ? 浓度/体积(ppm) = ?

12 Quantifying Airborne Concentrations of Chemical Agents 量化化学因素的大气污染物浓度
Can you rearrange this equation to convert ppm to mg.m-3 ? 能用该公式将ppm转换成mg.m-3 吗？ Conc by weight (mg.m-3) = Conc by volume (ppm) x Molecular weight (g) 24.06 浓度/重量 (mg.m-3) = 浓度/体积 (ppm) x 分子重量 (g) Conc by volume (ppm) = Conc by weight (mg.m-3) x Molecular weight (g) 浓度/体积 (ppm) = 浓度/重量 (mg.m-3) x 分子重量 (g)

13 Categories of Exposure Limits 接触限值的类别
Long Term Exposure Limits are expressed as a Time Weighted Average (TWA) normally over an eight hour period. This allows for exposures to vary through the working day so long as the average exposure does not exceed the limit. 长期接触限值采用时间加权平均值（TWA）来表示，一般都在8小时以上。只要平均接触不超过限值，可通过工作日进行接触变更。 Short Term Exposure Limit (STEL) normally over a 15 minute period are used when exposure for short periods of time occurs. 短期接触限值（STEL），一般超过15分钟，用于短期接触的情况。 Ceiling Limits are sometimes used and are concentrations that should not be exceeded during any part of the working exposure. 有时会使用上限，上限是指在任何工作时间内，都不能超过的限值。 "Skin" Notation - Substances can have a contributing exposure effect by the cutaneous route (including mucous membranes and eyes). 皮肤标记符号——确定皮肤（包括粘膜和眼睛）因接触物质所致影响。

14 Effects of Mixed Exposures 混合接触物的影响
Synergistic substances: known cases of synergism are considerably less common than the other types of behaviour in mixed exposures. 协同物质：已知协同作用的情况比混合接触中的其它行为类型要少。 Additive substances: where there is reason to believe that the effects of the constituents are additive, and where the WELS are based on the same health effects, the mixed exposure should be assessed using a formula. 添加剂：如确信影响成分的要素是添加剂，且WELS是以相同健康效 果为基础。应采用公式来评估混合接触。 Independent substances: where no synergistic or additive effects are known or considered likely, the constituents can be regarded as acting independently and the measures needed to achieve adequate control assessed for each separately. 独立物质：如未发现协同或相加作用或出现类似情况，则可视为各成 分独立作用，应采取措施，对各成分单独进行适当的控制评估。

15 Calculation of exposure with regard to the specified reference periods 指定参考周期内接触限值的计算
The 8-hour reference period 8小时参考周期 Exposures treated as equivalent to a single uniform exposure for 8 hours (the 8-hour time-weighted average (TWA) exposure). 接触系指8小时单次均匀接触（8小时时间加权（TWA）平均接触值） 。 Represented mathematically by: 可采用如下公式表达： C1 x T1 + C2 x T2 + ……. Cn x Tn 8 Where:其中 ： C1 is the occupational exposure C1是职业接触 。 T1 is the associated exposure time in hours in any 24-hour period. T1是任何24小时时间段内的相关接触时间（单位：小时）。

16 Calculation of exposure with regard to the specified reference periods 指定参考周期内接触限值的计算
The 8-hour reference period - Example 1 8小时的参考期 - 示例1 The operator works for 7h 20min on a process in which he is exposed to a substance hazardous to health. The average exposure during that period is measured as 0.12 mg m-3. 操作人员在接触对健康有害物质的工序中工作7小时20分钟。在该时间段内的平均接触限值是0.12 mg m-3 。 The 8-hour TWA therefore is: 8小时TWA： 7h 20min (7.33 h) at 0.12 mg m-3 7小时20分钟（7.33小时）为0.12 mg m-3 40min (0.67h) at 0 mg m-3 40分钟（0.67小时）是0 mg m-3 That is:即 (0.12 x 7.33) + (0 x 0.67) = 0.11 mg m-3 8

17 Calculation of exposure with regard to the specified reference periods 指定参考周期内接触限值的计算
The 8-hour reference period - Example 2 8小时的参考期 - 示例2 The operator works for 6h 00min on a process in which he is exposed to a substance hazardous to health. The average exposure during that period is measured as 0.5 mg m-3. The operator then works for a further 1 hour in which he is exposed to 1.5 mg m-3. 操作人员在接触对健康有害物质的工序中工作6小时。在该时间段内的平均接触限值是0.5 mg m-3 。 操作人员再继续工作1小时，接触限值为1.5 mg m-3 。 What is the 8-hour TWA ? 8小时TWA是什么？

18 Calculation of exposure with regard to the specified reference periods 指定参考周期内接触限值的计算
The 8-hour reference period - Example 2 8小时的参考期 - 示例2 The operator works for 6h 00min on a process in which he is exposed to a substance hazardous to health. The average exposure during that period is measured as 0.5 mg.m-3. The operator then works for a further 1 hour in which he is exposed to 1.5 mg.m-3. 操作人员在接触对健康有害物质的工序中工作6小时。在该时间段内的平均接触限值是0.5 mg m-3 。 操作人员再工作1小时，接触限值为1.5 mg m-3 。 What is the 8-hour TWA therefore is: 8小时TWA是什么？ 6h 00min (6.00 h) at 0.5 mg m-3 6小时00分（6.00小时） 0.5mg m-3 1h 00min (1.00 h) at 1.5 mg m-3 1小时00分（1.00小时）1.5 mg m-3 1h 00min (1.00 h) at 0.0 mg m-3 1小时00分（1.00小时） 0.0 mg m-3 That is: 即 (0.5 x 6.00) + (1.5 x 1.00) + (0 x 1.00) = 0.69 mg m-3 8

19 The short-term reference period 较短的参考期
Exposure should be recorded as the average over the specified short-term reference period (usually 15 minutes) and should normally be determined by sampling over that period. 接触限值为指定较短参考期的平均值（通常为15分钟），通常采用在该时间段内采样的方式来进行确定。 If the exposure period is less than 15 minutes, the sampling result should be averaged over 15 minutes. For example, if a 5 minute sample produces a level of 150 ppm and is immediately followed by a period of zero exposure then the 15-minute average exposure will be 50 ppm. 如果接触时间不到15分钟，采样结果应视为15分钟的平均值。例如， 如果接触仅5分钟，采样结果显示是150 ppm，则15分钟的平均接触 值是50 ppm。 That is:即： 5 x 150 = 50 ppm 15

20 Biological Monitoring Guidance Values 生物监测的指导意义
Complimentary technique to air monitoring. 是大气监测的补充 Biological monitoring is the measurement and assessment of hazardous substances or their metabolites in tissues, excreta or expired air in exposed workers. 生物监测是对有害物质、接触员工组织中有害物质代谢物、排泄​​物或其呼气进行测量 和评估。 Measurements reflect absorption of a substance by all routes. 测量反映物质在所有途径的吸收。 Particularly useful where exposure is by routes other than inhalation 对于有害物质通过进入途径，而不是通过呼气方式的情况，生物监测特别有用。 In most cases limits for Biological Monitoring are not statutory. 在大多数情况下，生物监测限制都不是法律强制规定的。 Biological monitoring undertaken needs to be conducted on a voluntary basis (i.e. with the fully informed consent of all concerned). 生物监测自愿实施（即，应获得所有有关方面的充分知情同意）。