Factories (Permissible Exposure Levels of Toxic Substances) Order 1996

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No. S 343

Factories Act

(Chapter 104)

Factories (Permissible Exposure Levels of Toxic Substances) Order 1996

In exercise of the powers conferred by section 59(11) of the Factories Act, the Minister for Labour hereby makes the following Order:

Citation and commencement

1. This Order may be cited as the Factories (Permissible Exposure Levels of Toxic Substances) Order 1996 and shall come into operation on 1st January 1997.

Definitions

2. In this Order —

“permissible exposure level” means the maximum time weighted average concentration of a toxic substance to which persons may be exposed;

“PEL(Long Term)” means the permissible exposure level over an 8-hour working day and a 40-hour work week;

“PEL(Short Term)” means the permissible exposure level over a 15-minute period during any working day;

“time weighted average concentration” means the concentration determined by adding together the products of each concentration and the corresponding time over which that concentration was measured, and dividing the sum by the total time over which the measurements were taken; as an illustration, if the concentration of benzene is measured at 4 ppm^a for 3 hours and 7.2 ppm^a for 5 hours, the time weighted average concentration will be 6 ppm^a, calculated as follows:

“toxic substance” means any substance in the form of gas, vapour, dust, fume, fibre or mist which may cause irritation, injury, illness, disease or any harmful effect to a person through ingestion, inhalation or contact with any body surface, and includes any substance specified in the Schedule.

Application

3. The permissible exposure levels of toxic substances prescribed in the Schedule shall apply to every factory where, in connection with any process or work carried on therein, there is produced or given off any toxic substance.

Determination of permissible exposure level in certain circumstances

4.—(1) Where PEL (Short Term) of a toxic substance is not prescribed in the Schedule, PEL (Short Term) of the substance shall be deemed to be exceeded if the time weighted average concentration of the substance measured over a 15-minute period during any working day exceeds 5 times PEL (Long Term) of that substance as prescribed in the Schedule.

(2) Where there is exposure to more than one toxic substance at the same time and the substances have similar harmful effects, the permissible exposure level shall be deemed to have been exceeded if the sum of the ratios between the time weighted average concentration and the permissible exposure level of each substance exceeds 1.

Illustration

Xylene and toluene are toxic substances with similar harmful effects. If there is exposure to these 2 substances at the same time at concentrations of 80 ppm^a (in the case of xylene) and 40 ppm^a (in the case of toluene), the sum of the ratios will be 1.6, calculated as follows:

Since the sum of the ratios exceeds 1, the permissible exposure level will have been exceeded.

(3) Where there is exposure to more than one toxic substance at the same time and the substances do not have similar harmful effects, the permissible exposure level shall be deemed to have been exceeded if the time weighted average concentration of any one of the substances exceeds the permissible exposure level of that substance.

Made this 25th day of July 1996.

MOSES LEE KIM POO

Permanent Secretary,
Ministry of Labour,
Singapore.

[ML A25/73; AG/SL/9/94/1]

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