Protective measures relating to the handling of styrene

Status:

completed 08/2006

Aims:

Styrene is chiefly employed in the manufacture of polystyrene and certain other plastics. It is also used as a solvent and co-reactant for a wide variety of polyester resins. Styrene presents a health hazard; its vapours have an unpleasant odour even at low concentrations below the occupational exposure limit value. Companies are frequently obliged to reduce the odour emissions. These obligations are met only when diffuse emissions are avoided and the exhaust air is treated in special exhaust air purification plants (e.g. thermal afterburning). Such exhaust air purification plants employ highly complex technology and entail high operating costs. In order to reduce the investment and running costs, exhaust air discharge volumes are generally reduced to a minimum, as the costs rise out of proportion to the rise in volume.

The objective was first to describe methods or procedures for the avoidance and/or minimization of the emissions. For this purpose, consideration had to be given to the boundary conditions arising in practice, since these necessitate different concepts for solutions. One reason for this is that semifinished or finished products vary widely in their dimensions (e.g. long pipes, shrouds, ships' hulls). Another reason are the different manufacturing techniques employed (e.g. rolling or injection processes, manual or automatic methods).

Besides study of the influence of organizational methods upon the reduction of the styrene vapour emissions in the plants, the purpose of the project was to identify suitable systems for collection of the waste air and ventilation techniques for the various manufacturing and processing methods for products containing styrene. At the end of the project, dedicated concepts for protective measures were to have been produced with which the exposure concentrations in the various processing methods can be reduced effectively.

Activities/Methods:

Existing expertise in the BGs was first surveyed and compiled. Practical experience was then obtained from affected companies. The information collected was presented at the G3 seminar on technical protective measures for tasks involving styrene, held in 2005.

Results:

The results as presented in the form of BGIA Report 4/2006 were based upon the expertise of the BGs and of practising professionals within companies. Based upon information thus gained, checklist BGI 613 concerning styrene and preparations containing styrene is to be reviewed.

Owing to the wide differences in corporate structure, the large number of different tasks, and the strict requirements of the German Federal Control of Pollution Act (Bundesimmissionsschutzgesetz), information must be provided to the plants very selectively in order for the OH&S and environmental protection measures to be implemented properly. Concepts for measures dedicated to particular methods and tasks are also required for optimization of the very high investment costs of the technologies for waste air purification.

For the majority of tasks involving styrene, the focus lies firmly upon the reduction of diffuse sources of emissions. Unavoidable emissions must be collected in order for human health to be safeguarded. The collection and ventilation processes required for this purpose must be designed such that large loads can be removed from the working area and transported to a waste gas purification facility with the lowest possible volumetric flows. Different exhaust air purification systems should be employed depending upon the mass flows of styrene vapours in the collected air.

Areas exist, not least in the non-stationary processing of styrene (work on construction sites, laying of flooring, bodywork repair, etc.), in which neither technical nor organizational measures enable the occupational exposure limit value to be observed. Respiratory protective equipment must be worn during these tasks.

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