Methods to control styrene exposure in the reinforced plastics industry: Dissertation

Research output: ThesisDissertationCollection of Articles


Currently, about 75% of Finnish reinforced polyester lamination workers are exposed to styrene concentrations exceeding the current occupational exposure limit of 20 ppm. Several measures have been proposed to control styrene exposure, but only a few of them are capable of keeping the styrene concentration below 20 ppm. The present study was carried out to evaluate current ventilation systems in reinforced plastic plants and to develop new, effective ventilation systems for controlling styrene exposure. The roles of styrene-suppressed resin and styrene emission during different phases of the moulding process were also studied. Styrene exposure and the performance of current ventilation systems were measured in 17 reinforced plastics plants. Better styrene control was sought experimentally by investigating the effects of unidirectional airflow on a worker's exposure, by testing local exhaust and local air supply ventilation methods in controlling laminator's exposure and by examining the possibilities to improve local ventilation using an automatically moving ventilation unit. The characteristics of styrene emission during hand lay-up and the effect of a rolled area on styrene evaporation were also determined. Dilution ventilation systems are common in Finnish reinforced plastics plants. In many cases, the ventilation system was incorrectly dimensioned and workers were exposed to high styrene concentrations. High dilution airflow rates, over 850 m3 kg-1, may be needed before a concentration level below 20 ppm is achieved with the resin consumption rates common today. In order to meet the present exposure limit, local ventilation techniques should be used in combination with other control measures. Well-designed zonal ventilation methods (e.g., a horizontal airflow tunnel) produced a favourable airflow pattern for controlling styrene vapours in the lamination area. However, work practices must be synchronized with the airflow pattern before low styrene exposure levels are reached. A worker standing in a unidirectional airflow facing downstream may also receive significant exposure due to contaminant transporting eddies formed downstream of the body. It is possible to control this type of exposure with a local air supply unit located over the worker. Styrene control during hand lay-up moulding is also possible with the use of several local exhaust hoods. It was estimated that adequate styrene control can be achieved when the control velocity at the edge of the mould is 0.15-0.2 m s-1 and the exhaust airflow rate per laminate area is between 0.1 and 0.2 m3 s-1 m-2, depending on the shape of the mould. An automatically moving local ventilation unit, equipped with local exhaust and a local air supply, was able to keep the styrene concentration near or below 20 ppm when medium-size products were laminated with the hand lay-up method. A styrene concentration of below 20 ppm was also obtained when a new type of spray booth, equipped with automatically moving curtains, was used and when the control velocity was at least 0.3 m s-1 during the spray-up of gelcoat resin. The use of vapour-suppressed resin reduced the total styrene emission by 30-60%, but the reduction was much lower during active lamination. After rolling, the emission from the vapour-suppressed resin was found to be very low, and, therefore, the emission rate was dependent on the size of the surface area rolled simultaneously. The use of these resins is beneficial, especially when large products are laminated.
Original languageEnglish
QualificationDoctor Degree
Awarding Institution
  • University of Eastern Finland
  • Kalliokoski, Pentti, Supervisor, External person
  • Niemelä, Raimo, Supervisor, External person
  • Lehtimäki, M., Supervisor, External person
Award date29 Aug 1998
Place of PublicationEspoo
Print ISBNs951-38-5250-4
Electronic ISBNs951-38-5251-2
Publication statusPublished - 1998
MoE publication typeG5 Doctoral dissertation (article)


  • occupational safety
  • occupational health
  • plastics industry
  • indoor air
  • styrene
  • air quality
  • ventilation (air conditioning)
  • local ventilation


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