Hazardous substances

4. Hazardous substances
4.1. Scope
4.1.1. This chapter contains additional and specific requirements and information
for hazardous substances (including dusts, fumes and gases) to help employers, workers
and competent authorities apply the general principles set out in Chapters 2 and 3. Many
of the measures described here apply to biological substances, but no attempt was made
to cover the special control measures required for infectious materials, which will be the
subject of another planned ILO publication.
4.1.2. In the application of the provisions in this chapter, due consideration
should be given to the fluctuations in different ambient factors that may exacerbate the
adverse effects on the health of workers, the general public and the environment.
4.1.3. Where the workers are exposed to hazardous chemicals (dusts, fumes,
gases), the provisions of the ILO code of practice Safety in the use of chemicals at work
(Geneva, 1993) should apply.
4.1.4. Exposure to hazardous substances should be kept as low as reasonable and
practicable, and within the established exposure limits.
4.2. Assessment
4.2.1. As the first stage of the assessment, the employer should inspect the
workplace and obtain information on:
(a) hazardous substances that are present or likely to occur, along with other hazardous
ambient factors (see paragraph 3.1.3 above);
(b) activities that take place;
(c) any hazardous substances or processes that may easily be eliminated.
4.2.2. Consideration should be given to obtaining information on:
(a) the intrinsic hazards of the raw materials, products and byproducts according to the
physical states (e.g. solid, liquid, gas) in which they occur or are produced;
(b) the ambient conditions (e.g. barometric pressure, temperature, etc.) under which the
hazardous substances are used or produced;
(c) the impact of either the change in phase of the hazardous substances (e.g. solid to
liquid phase) or fluctuations in the ambient conditions on the health of workers
exposed, the public and the environment.
4.2.3. In the case of chemicals, the employer should obtain information from
suppliers in accordance with the provisions of Chapter 5 of the ILO code of practice
Safety in the use of chemicals at work (Geneva, 1993). Where this is not practicable,

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