By workplace & process
Contact moulding fills the air with styrene vapour; grinding and trimming the cured laminate fills it with dust. Composite work has two distinct exposures, and the test has to confirm capture for both.
The short answer
Composite and fibreglass work produces its hazards in two stages. During contact moulding the polyester resin gives off styrene vapour that fills the air around the bench; once the laminate has cured, grinding and trimming it releases fine GRP dust. The two behave differently and are controlled differently, so a shop that captures one well can still be exposing people to the other - and the test has to cover both.
The detail
Styrene is the main concern during hand lay-up and spray-up. It irritates the nose, throat and lungs, can cause drowsiness, headaches and poor concentration, and is an eye and skin irritant. Its workplace exposure limit is 100 parts per million as an eight-hour average with a 250 parts per million short-term limit, and open moulding is exactly the kind of work that pushes towards those figures without good capture.
The dry stage is different. Grinding, cutting and trimming cured glass-reinforced plastic produces dust that can cause fluid to collect on the lungs and irritate the airways and skin. There is no specific limit for GRP dust, so it falls under the nuisance dust limit of 10 milligrams per cubic metre and should be kept below it. Wet vapour that drifts and dry dust that is thrown at speed need different capture, which is why one general extract seldom controls both.
What it means for you
A thorough examination and test of composite-shop LEV confirms that capture at the lay-up bench or booth is holding the styrene vapour and that finishing extraction is catching the grinding dust at source, each moving air at the rate it was commissioned to. Because the two exposures peak at different points in the job, the examiner checks the capture for each against what it controls, at least every fourteen months with user checks between.
Lower-styrene resins and closed-mould methods cut vapour at source and are the better route where they can be used, but a great deal of work is still open lay-up, where LEV remains the practical control. Proving that both the wet-stage and dry-stage capture still perform - not just the one that is easiest to see - is what keeps a composite shop's exposures in check.
The service behind the guide
We test composite-shop LEV - lay-up bench capture and finishing extraction - against the styrene vapour and GRP dust it has to control, with a clear report.
Questions
Styrene vapour from polyester resin during contact moulding. It irritates the nose, throat and lungs and can cause drowsiness and headaches. Its exposure limit is 100 parts per million as an eight-hour average, 250 parts per million short-term.
Yes. Grinding cured GRP produces dust that can cause fluid on the lungs and respiratory and skin irritation. There is no specific limit for it, so it falls under the nuisance dust limit of 10 milligrams per cubic metre and should be controlled below that.
Wet lay-up gives off vapour that rises and spreads, best caught by capture close to the bench or a booth. Dry finishing throws dust better caught by downdraft or on-tool extraction. A single arrangement rarely handles both well.
Lower-styrene resins and closed-mould methods can cut vapour at source, which is the preferred route. Where open lay-up continues, LEV remains the practical control and still has to be tested.
At least every fourteen months under COSHH, with user checks between. The test confirms both the lay-up capture and the finishing extraction still perform.
Phoenix Duct Clean · by the numbers
We test composite-shop LEV - lay-up bench capture and finishing extraction - against the styrene vapour and GRP dust it has to control, with a clear report.