Reducing risks associated with using coating powders - employers
Powder coating products are important for protecting surfaces from corrosion and producing an attractive finish. Powder coating is an alternative finishing process to spray painting. Powders in their uncured state, present health and safety hazards and can harm health and the environment. This guidance outlines good control practice and is intended for employers. It is also useful for trade union and employee safety representatives.
For most powders, significant exposure can result in health effects such as occupational asthma and skin irritation and skin sensitisation.
The health hazards of using commonly available coating powders arise from:
- direct skin contact with the powders
- breathing in powders in the air
However, some pigments and curing/hardening agents used in some powders are toxic, especially:
- TGIC (triglycidyl isocyanurate) and
- TMA (tri-mellitic anhydride) and
- Lead chromate based pigments
The safety data sheet (SDS) will list the harmful ingredients in the coating powder. The associated health effects covered by the 'Hazard statements' (under the new Globally Harmonised System (GHS)) eg H302 'harmful if swallowed' or 'Risk phrases' under CHIP), R22 'harmful if swallowed'. Another example is if the product is classified as H317 (may cause an allergic skin reaction) or R43 (may cause sensitisation by skin contact), these mean you need to watch out for the early signs of skin irritation (dermatitis). If the listed ingredients include any of the above named chemicals you should also read the webpages on these powders see Specialist powders.
Powder coating products are classified as 'substances hazardous to health' because they are breathable dusts. The UK Workplace Exposure Limits are set at 10 mg/m3 of total inhalable dust and 4 mg/m3 of respirable dust, (8-hour time-weighted averages). Up to 10% of a powder coating product can be 'respirable' which is too fine to see when dispersed in air, but is taken deep into the lungs during normal breathing.
As a downstream user of powder coating products, you are required to identify and apply suitable measures that allow you to control risks. These measures are normally communicated to you by the powder coating supplier via the SDS. You must use the risk management measures described in these SDSs and other information that is provided to you by your supplier or alternatively you can apply equally effective control measures.
High risk activities
The risk of harm occurring is highest when:
- using powders containing the above mentioned substances;
- spraying powder in poorly ventilated powder-coating booths;
- following poor systems of work, such as leaning into the coating booth when spraying;
- carrying out powder transfer, maintenance and cleaning work;
because these activities have been demonstrated to create the highest levels of dust in the air breathed in by workers.
To begin to control exposure to hazardous materials you need to do a risk assessment. This involves identifying the harmful substance (using product labels and the MSDS) and thinking about:
- the route into the body (ie breathed in, skin contact or swallowed);
- how often people work with the substance and for how long;
- the task being done;
- anyone else who could be exposed (eg maintenance workers);
- people who could be exposed accidentally;
- where necessary, providing appropriate health surveillance.
To control exposure to hazardous materials, you need to avoid using the substance/process altogether. However, if that is not possible, use the risk assessment process to make sure measures are in place to control the identified risks.
Control measures include:
- changing the process to reduce risks (eg lower the temperature to reduce the amount of vapour produced);
- controlling exposure at source by enclosing the process or activity to minimise escape or release;
- planning the storage and disposal of materials;
- making sure the workplace is easily cleaned;
- providing washing and changing facilities;
- providing appropriate personal protective equipment (PPE).
You must check and review your control measures regularly to make sure they are effective. This should include making sure:
- plant and equipment are maintained (particularly ventilation equipment);
- systems of work are being followed;
- personal protective equipment is suitable, properly fitted and maintained.
- that information, instruction and training is provided.
See COSHH Essentials sheet G222 covering engineering controls at powder coating processes.
More information is available at the COSHH homepage.
Tips and good practice
You should choose a suitable powder coating that presents the lowest risk to your workers' health and safety, (and to the environment). Talk to your supplier or trade association for advice. Take care when selecting an alternative powder coating as some also contain other hazardous substances such as isocyanates.
The following factors should be considered for working safely with powders:
- Minimise the amount of manual spraying carried out – many coating booths are automatically operated.
- Ensure that your spray booth is working at its optimum so that the air entering the system is at least 0.5 metres per second. Dust found on the floor around openings in the booth will indicate where this is not achieved.
- Ensure that all doors in the booth are kept shut (as appropriate to the work) and that the size of all openings are minimised to ensure maximum efficiency of the LEV.
- If using conveyorised spray booths stand outside the booth to spray and do not lean inside the booth.
- Never spray towards another operator working either in tandem or opposite.
- Eliminate manual transfer of powders from the delivery box to the hopper. Consider partial enclosure and extraction of the feed hopper or other dust loading equipment.
- The amount of powder sprayed should be kept to the level that minimises its usage and achieves the desired finish, by controlling gun settings.
- Provide suitable PPE including respiratory protective equipment (RPE with Assumed Protection Factor (APF) of 20) and make sure it is worn properly during spraying.
- Train your employees in safe powder coating techniques to minimise exposure
- Practise good housekeeping by keeping work areas around the spray booths clean by using an industrial vacuum cleaner (ATEX compliant and dust tight to IP6X, provided with suitable filtration) rather than sweeping up with a broom.
- Follow safe systems of work for cleaning the booth and maintenance activities; in particular, the use of compressed air for cleaning should be kept to a minimum and operators should avoid standing inside the booth to clean it by using long-handled rubber scrapers (not brushes) and compressed air lances. The booth extraction should always be operating whilst cleaning is taking place. RPE should be provided with an APF of 40 for cleaning and maintenance activities.
- Provide easily accessible washing facilities and facilities for changing clothes with storage. Ensure good standards of personal hygiene by keeping overalls clean by regular washing (including arrangements for laundering) and by washing hands before eating and drinking. Never eat or drink in the work area.
See COSHH Essentials sheets R3/R4/R5 covering RPE provision.
The law on the main hazards associated with powder coating
Hazardous substances in coating powders must be controlled in line with the Control of Substances Hazardous to Health (COSHH) Regulations. See HSE's COSHH webpages for more information.