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1.Enacted and promulgated of total eleven articles of the Standards by the Ministry of the Interior Order of the Tai-Nei-Lao-Tzu No. 58463 on Aug 7, 1974.
2.Amended and promulgated by the Ministry of the Interior Order of the Tai-Nei-Lao-Tzu No. 17206 on Apr 17, 1981.
3.Amended and promulgated by the Ministry of the Interior Order of the Tai-Nei-Lao-Tzu No. 302043 on Apr 15, 1985.
4.Amended and promulgated by the Council of Labor Affairs, Executive Yuan Order of the Lao-An-3-Tzu No. 123510 on Jun 30, 1995.
5.Amended and promulgated by the Council of Labor Affairs, Executive Yuan Order of the Lao-An-3-Tzu No. 0920073294 on Dec 31, 2003.
6.Amended and promulgated of attachment 1 and 2 of the Standards by the Council of Labor Affairs, Executive Yuan Order of the Lao-An-3-Tzu No. 0980146513 on Jan. 5, 2010.
7.Amended and promulgated of Article 11 of the Standards by the Council of Labor Affairs, Executive Yuan Order of the Lao-An-3-Tzu No. 0990145030 on Jan. 26, 2010. Amended attachment 1 and 2 of the Standards was implemented on Feb. 1, 2010.
8.Amended on June 27, 2014.
9.Amended on March 14, 2018.
10.Amended on April 11, 2025.

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Article 1 These Standards are promulgated in accordance with Article 12, Paragraph 2 of the Occupational Safety and Health Act.
Article 2 The employer shall ensure that workers’ exposure to hazards at job sites is below the permissible limits specified in Attachment 1 or Attachment 2. If a hazardous substance not listed with a permissible exposure limit in Attachment 1 is detected, it shall be deemed to exceed the Standard.
Article 3 As used herein, the permissible exposure limit refers to the following:
1. The 8-hour time-weighted average: The 8-hour time-weighted average for substances not designated as “Ceiling” in Attachment 1 refer to levels to which workers may be repeatedly exposed during a standard eight-hour workday without adverse health effects.
2. The short-term exposure limit: For any substance without designation of "Ceiling" in Attachment 1 and any substance listed in Attachment 2, the short-term exposure limit shall be calculated by multiplying the "8-hour time-weighted average" by the corresponding "Excursion Factor" as specified in the following Attachment. This concentration is the level at or below which it is believed that workers may be continuously exposed for any 15-minute period without suffering from unbearable irritation, chronic or irreversible tissue damage, narcotic or fainting effects, increased risk of accidents, or reduction in work efficiency.
3. Ceiling limit: An employee's exposure to any substance designated as “Ceiling” in Attachment 1 shall not exceed the Ceiling limit specified therein at any time during exposure, to prevent the employee from suffering from unbearable irritation or physical impairment.
Article 4 As used herein, the time-weighted average shall be computed as follows:
TWA= (C1T1 + C2T2+------+CnTn)/ (T1+ T2+---+Tn)
Where:
TWA is the time-weighted average for the computed working period of (T1+ T2+---+Tn).
Ci is the concentration during any period of time Ti.
Ti is the duration in hours of the exposure at the concentration Ci.
Article 5 As used herein, “ppm” (parts per million) refers to one cubic centimeter of a gaseous hazardous substance per cubic meter of air, measured at 25oC and 760 torr.
Article 6 As used herein, “mg/m^3” refers to the concentration of particulate or gaseous hazardous substances expressed as milligrams per cubic meter of air at 25 oC and 760 torr.
Article 7 As used herein, “f/cc” refers to the number of fibers per cubic centimeter of air at 25°C and 760 torr.
Article 8 The concentration of hazardous substances in the air at job sites, to which employees are exposed, shall comply with the following requirements:
1. The time-weighted average over the entire working day shall not exceed the permissible exposure limit corresponding to an 8-hour time-weighted average.
2. The time-weighted average of any continuous 15-minute period shall not exceed the short-term exposure limit.
3. At no time shall the concentration exceed the Ceiling limit.
Article 9 In the case of exposure to two or more hazardous substances in the air of a job site, where their combined effects on health are neither synergistic nor independent, such effects shall be deemed additive, and the combined exposure shall be computed as follows:
Em=(C1/L1)+(C2/L2)+-----(Cn/Ln)
Where:
Em is the equivalent exposure for the mixture of hazardous substances in air.
Ci is the concentration of a particular substance i.
Li is the permissible exposure limit given for that particular substance i.
Once the sum (Em) exceeds unity (1), the exposure shall be considered to have been exceeded.
Article 10 These Standards shall not apply to the determination of the following matters:
1. Relative index of toxicity between two different hazardous substances.
2. Ambient air pollution indices outside the workplace.
3. The sole basis for the determination of occupational diseases.
Article 11 These Standards shall take effect on July 3, 2014.
In addition to number 4, 43, 231, and 477 in Attachment 1 of Article 2, as amended and promulgated on March 14, 2018, taking effect on July 1, 2018; and number 15, 211, and 445 in Attachment 1 of Article 2 and Attachment 2, as amended and promulgated on April 11, 2025, taking effect on January 1, 2027, these amendments to these Standards shall come into force on the date of promulgation.