Polyester and Styrene in Orhangazi Boat Building

Boat building in Orhangazi and a process-based hazard map

Orhangazi is a district at the western end of Lake İznik, on the Bursa–Yalova highway and close to the Gulf of Gemlik. There is no organised industrial zone in the district on the list of active OIZs of BTSO (Bursa Chamber of Commerce and Industry); industrial facilities are spread throughout the district. The Orhangazi district report of BEBKA (Bursa Eskişehir Bilecik Development Agency) notes boat and yacht building, alongside the automotive supply industry and iron and steel, as an activity that sets the district apart from Bursa's other districts. In most of these workshops, hulls, decks and interior parts are made from glass-reinforced polyester (GRP). Boat building safety therefore resembles the risk profile of a chemical business more than that of a metal workshop.

In GRP manufacturing, the work passes through several stages, from mould preparation to fitting out the hull. Each stage has a different main hazard:

Stage	Main hazard	Key measure
Mould preparation and gelcoat	Styrene vapour, release agent and solvent	Local exhaust ventilation, closed containers, respirator suitable for organic vapours
Hand lay-up or spray lamination	Heavy styrene vapour, resin splashes, fire	General and local ventilation, gloves and eye protection, control of ignition sources
Curing	Heat build-up in mixing containers and waste	Curing waste resin by spreading it out, metal waste bin with lid
Demoulding	Lifting a heavy hull, crushing	Lifting plan, sling selection, no one under the load
Cutting, grinding, sanding	Glass fibre and resin dust, noise, vibration	Hand tools with extraction, dust mask, hearing protection
Fitting out and lamination inside the hull	Confined space, accumulated vapour, limited escape	Mechanical ventilation, gas monitoring, permit to work, attendant

All the risks in the table should appear as separate rows in the risk assessment. For demoulding and moving, the roles of the crane team are described in our article on the duties of crane signallers and slingers.

Styrene vapour: why, and how is it reduced?

Most polyester resins contain styrene, which keeps the resin fluid and reacts during curing. As long as the surface of the resin is left exposed during lamination, styrene evaporates. The vapour is heavier than air; it accumulates at the bottom of the hull, in the bilge area and in mould hollows. Short-term high exposure causes eye and respiratory irritation, headache, dizziness and poor concentration. In 2018 the International Agency for Research on Cancer (IARC) classified styrene as "probably carcinogenic to humans" (Group 2A). Styrene exposure should therefore be treated not as a familiar smell but as a chemical exposure that needs to be reduced.

The Regulation on Health and Safety Measures in Work with Chemical Agents requires the employer first to eliminate the hazardous substance or replace it with a less hazardous one and, if this is not possible, to minimise exposure. In a boat workshop, this translates into the following order:

Change the process. Vacuum infusion or closed mould methods instead of open-mould hand lay-up reduce the time the resin is in contact with air.
Change the resin. Low-styrene resins or resins with reduced styrene emission can be evaluated together with the supplier.
Extract at source. The extraction inlet is placed close to the low level where vapour accumulates; inside the hull, an arrangement is set up that blows in clean air and draws contaminated air from the bottom.
Keep containers closed. Resin buckets, acetone containers and resin-soaked rags are kept covered.
Use personal protection. A half or full face mask with filters suitable for organic vapours comes only after the measures above. For filter types and service life, see our article on gas mask filters.

For the occupational exposure limit value for styrene and the properties of other components, use section 8 of the resin's safety data sheet and the current Annex 1 table of the regulation. We plan measurement of styrene levels in the workplace with authorised laboratories and enter the results into the risk assessment.

Glass fibre and cured resin dust

Trimming the edges of a demoulded hull, drilling holes and sanding produce heavy dust. This dust is a mixture of glass fibre particles and cured resin dust. Itching and irritation of the skin, a stinging sensation in the eyes and irritation of the respiratory tract are the most common complaints.

Hand tools with extraction and local exhaust close to the cutting point prevent dust spreading at source.
No cleaning with compressed air; dust is removed with an industrial vacuum cleaner.
Clothing: Long-sleeved work clothing closed at the wrists and neck is worn; dusty clothing is not taken into the canteen or home.
Respiratory and eye protection: A dust mask suited to the dust level and goggles are used; you can select them using our article on FFP1, FFP2 and FFP3 dust masks.

Skin complaints may also come from the resin and hardener themselves. Changing gloves regularly and using a suitable cleanser instead of solvent for hand cleaning reduce the risk of occupational dermatitis.

Fire in boat building: resin, peroxide and acetone

From a fire perspective, boat building combines three separate sources: flammable resin and styrene, organic peroxide hardener and the acetone used for cleaning tools.

Peroxide and accelerator are never mixed directly. Direct contact between cobalt accelerator and peroxide hardener can cause a violent reaction. The two are stored in separate places with separate measuring containers and are added to the resin only separately.
Peroxide is stored cool and apart. It is kept away from heat sources, sunlight and flammable materials, within the temperature range specified by the manufacturer.
Waste resin heats up. Resin left in a mixing container generates heat as it cures; heat building up in a full bucket can go as far as ignition. Waste resin is cured by spreading it in a thin layer, and resin-soaked rags are collected in a metal bin with a lid.
Acetone and styrene vapour seek an ignition source. Grinding sparks, welding, portable heaters and cigarettes are kept away from the lamination area. For bonding containers during transfer, see our article on static electricity and earthing.

Confined space work inside the mould and hull

A worker laminating inside a growing hull, in the bilge or in compartments is in a space with limited entry and exit and naturally inadequate ventilation. These spaces should be treated as confined spaces and made subject to a written permit to work:

Oxygen and flammable vapour levels are measured before entry and throughout the work.
Mechanical ventilation is switched on and not turned off during the work.
An attendant outside is in continuous communication with the worker inside.
Only lighting and tools that comply with the explosion protection document are used inside.
How a rescue will be carried out is planned and practised before the work.

You can find the definition and permit system in our article on working in confined spaces, and how to carry out measurements in gas testing before confined space entry.

Health surveillance: what does the physician look at?

Since styrene, peroxide, glass fibre and noise are present together, health surveillance in a boat workshop is planned according to the risk. In pre-employment and periodic examinations, the physician usually assesses the following:

Eye, skin and respiratory complaints; history of asthma and allergy
Complaints that may be related to solvent exposure, such as headache, dizziness and difficulty concentrating
Hearing in workers doing grinding and sanding
If considered necessary, lung function testing, hearing tests and biological monitoring of styrene exposure

The legislation does not fix which test is carried out at what frequency; the workplace physician decides according to exposure measurements and the risk assessment. We plan tests with authorised laboratories and healthcare facilities. The periodic examination interval depends on your hazard class; you can check your class and obligations with the OHS obligation calculator tool. Details of the service we provide to businesses in Orhangazi are on our Orhangazi OSGB page, and the general risks of the sector on our chemicals and plastics page.

Frequently Asked Questions

If workers have got used to the smell of styrene, does that mean the danger has decreased?

No. The sense of smell becomes dulled with continuous exposure; not noticing the smell does not show that the level in the air has fallen. The exposure level can only be determined by an authorised laboratory's measurement.

Does lamination inside the hull count as confined space work?

Every hull interior and compartment with limited entry and exit, inadequate natural ventilation and the potential for vapour build-up should be assessed as a confined space. This work is carried out with measurement, ventilation, an attendant and a written permit to work.

How should we store peroxide hardener?

In line with the manufacturer's safety data sheet, store it in its original container in a cool place, away from sunlight and heat sources, separate from flammable materials and cobalt accelerator. Keep separate measuring containers for the two substances.

What is the hazard class of our boat workshop?

The hazard class is determined from the Annex 1 list, renewed in 2025, according to the NACE code of the main activity carried out at the workplace. Check your code in your SGK registration and compare it with the list; if there is more than one main activity, the higher class applies.