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Working Environment Measurement Standards
Ministry of Labour Notification No. 46 of April 22, 1976

Latest Amendments:
Ministry of Health, Labour and Welfare Notification No. 191 of April 27, 2001
作業環境測定基準：原文

  1. Article 2.The concentration of dust of sand and stones, rocks, ores (minerals), metallic materials or carbon in the air of such indoor workplaces prescribed in item 1, Article 21, the Enforcement Order of Industrial Safety and Health Law (Cabinet Order No. 318, 1972, hereinafter referred to as the Cabinet Order) shall be measured in accordance with the provisions specified in the following :
      1. Vertical and horizontal lines are drawn at equal intervals of not more than 6m on the floor of a unit work area (refers to such a necessary section that is designated for working environment based on the condition of distribution of harmful substances and range of movement of workers within the area of a workshop concerned, hereinafter the same shall apply) and a sampling point is provided at each intersection of those lines at a position 50 to 150 cm above the floor (except such a point where measurement is very difficult due to equipment etc.). However, when it is obvious that the concentration of dust of sand and stones, rocks, ores (minerals), metallic materials or carbon is substantially uniform, vertical and horizontal lines can be drawn at equal intervals of more than 6 m on the floor of a unit work area and a sampling point provided at each intersection of those lines.
      2. Sampling points shall be provided at not less than 5 proper points though when they become less than 5 points then the above rule is applied regardless of the provisions of the preceding item. However, when the unit work area is very narrow and it is obvious that the concentration of dust of sand and stones, rocks, ores (minerals), metallic materials or carbon is substantially uniform, the number of sampling points may be less than 5.
      1. The measurement prescribed in the preceding items shall be made at such time when work is regularly performed.
      2. At such a unit work area where work is performed at a place in close vicinity to the source of emission of dust of sand and stones, rocks, ores (minerals), metallic materials or carbon in addition to the measurement prescribed in preceding three items, measurement shall be made at such a time when the concentration of dust of sand and stones, rocks, ores (minerals), metallic materials or carbon in the air seems to become the highest of those hours during which the work is performed at such a position where the work is performed.
    3. The collection of sample air at one sampling point shall be made continuously for not less than 10 minutes. This rule, however, does not apply to such a case wherein measurement is made by the relative concentration indication method.
    4. The concentration of dust of sand and stones, rocks, ores (minerals), metallic materials or carbon in the air shall be measured by one of the following methods.
      1. Filtration sampling method using a particle size separator and gravimetric analysis.
      2. Relative concentration indication method (this is limited to such a case wherein the method listed in a. is simultaneously performed at more than one measuring point in the unit work area concerned).
  2. A particle size separator prescribed in a) of item 4 shall be such a separator that has the characteristics shown in the following diagram, or for those separators which do not have the characteristics shown in the following diagram, such a separator that is capable of obtaining a value equal to a measured value which is obtained by a particle size separator proved to have said characteristics.
    Pentetration Rate
    • Remarks : In this diagram, P, D, and DO shall be defined as follows
    • P : Penetration Rate
    • D : Aerodynamic Particle Diameter of Dusts(μm) DO : 7.07 μm
    Aerodynamic Particle Diameter of Dusts
  3. Notwithstanding the provision of item 4 of paragraph 1, the measurement of the concentration of dust may be done by the relative concentration indication method only under the approval of the Chief of the Labour Standards Inspection Office who exercises jurisdiction over the area where the work area concerned is located (hereinafter referred to as the "Chief of the competent Labour Standards Inspection Office"). The approval may be given in case of the evaluation of working environment measurement which is prescribed in paragraph 1, Article 26-2, Ordinance on Prevention of Hazards due to Dust (Ministry of Labour Ordinance No. 18, 1979) has been done more than 2 years, and those results are all classified into Control Class 1. In this case measurement shall be made in accordance with the following instructions:
    1. The equipment to be used for the measurement shall be calibrated at least once every year periodically by one designated by the Director General of the Labour Standard Bureau, Ministry of Health Labour and Welfare.
    2. The conversion factor into mass concentration (K-factor) shall use a value which is produced by the equipment calibrated by the provisions of the preceding item or a value which is decided by the Director General of the Labour Standard Bureau, Ministry of Health Labour and Welfare.
  4. An employer who wishes to apply for the approval stipulated in the preceding paragraph shall fill in the Request for Special Approval on Working Environment Measurement (Form No. 1) and the Notification of Result of Working Environment Measurement (Form No. 2) attached to the following documents:
    1. A sketch of the workplace
    2. Drawing (s) showing the emission source of substances to be measured in the unit work area, the arrangement of major facilities and the sampling points
  5. The Chief of the competent Labour Standards Inspection Office shall, upon deciding whether or not to approve the petition specified in paragraph 3, notify the decision to the said employer in writing as soon as possible.
  6. An employer who has been approved in compliance with paragraph 3 shall, as soon as the evaluation of working environment measurement which is done after the above approval is not to be classified into Control Class 1, report it in writing to the Chief of the competent Labour Standards Office.
  7. The Chief of the competent Labour Standards Office shall revoke the approval, as soon as the said official recognized that the unit work area to have been approved by the provision of the paragraph 3 is not classified into Control Class 1 or difficult to keep the condition of Control Class 1, when the said official has received the report stipulated by the preceding paragraph or inspected the workplace.
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