2-pack isocyanate paints

Working with isocyanate Paints

Paints containing isocyanate are used extensively in motor vehicle repair (MVR) as almost all MVR bodyshops use 2-pack or ‘2K’ isocyanate-containing paints.

Isocyanates are used in some water-based paints, most base coats and almost all lacquers. 'Water-based' does not mean 'isocyanate-free', just that it is emulsion based and has reduced levels of solvents.

Using isocyanates is one of the main causes of occupational asthma reported in the UK and, for years, vehicle paint sprayers have been the group most at risk. MVR paint sprayers have a significantly higher risk of getting asthma compared with the UK working population. Every year a significant amount of paint sprayers are diagnosed with isocyanate asthma and most have to leave the industry, putting livelihoods at risk.

Other workers in bodyshops are also sometimes affected. For example maintenance personnel, managers and others who work in close proximity to spray booths or rooms.

This spray mist containing isocyanate may also worsen existing asthma. Once people are affected, even very low exposure levels can trigger an attack. Skin contact with isocyanates may cause dermatitis and may also trigger respiratory sensitisation.

Information, instruction and training

Information, instruction and training is required when working with any substance hazardous to health, such as isocyanates. Due to the high hazard nature of isocyanate containing materials, these products are restricted under (UK) REACH and the information, instruction and training needs to be robust and suitable to the hazard presented.

Training needs to be adequate and appropriate to the use of the substance (which includes any specific circumstances as to where it is used such as in Great Britain) and in line with the restriction.

The training requirements for hazardous substances can be found in the REACH list of restrictions.

Employers have a legal duty to ensure that all paint sprayers have successfully completed the required training before using isocyanate paints. Industry bodies for example Safe Use and Handling of Diisocyanates Trainings (on safeusediisocyanates.eu) have worked together to produce training for all isocyanate use scenarios. It is the responsibility of the employer to ensure all information, instruction and training is appropriate for the activities being undertaken and meets applicable regulations.

If you keep a record of a paint sprayer successfully completing appropriate training, you are demonstrating compliance with the law. Information, instruction and training is not a one-off exercise and should be reviewed and updated whenever significant changes are made to the type of work carried out or to the work methods used. Training should also be repeated at least every 5 years.

Keeping yourself protected from isocyanate risks

Here are some key tips for vehicle paint sprayers and owners of motor vehicle repair bodyshops on protecting themselves.

Vehicle paint sprayers

Never spray paint containing isocyanates outdoors except when undertaking SMART paint spraying outside the booth or room - the risk of developing occupational asthma occurs because paint spraying produces a lot of invisible airborne mist that you can breathe in. All spraying should be undertaken in a suitable local exhaust ventilation (LEV) system such as a spray booth or spray room.
Always wear air-fed breathing apparatus when spraying and know how to safely leave or enter your booth or room during the clearance time.
Do not lift your visor too soon – find out more on safe use and types of RPE.
Your booth or room takes time to clear of mist, so know the measuring paint spray booth clearance time and make sure everyone else does too
Your employers should check the controls are working by measuring workers’ exposure to isocyanate. The only way to do this (and accepted by the MVR industry) is by providing a urine sample for analysis
Biological monitoring can help dutyholders demonstrate that they are fulfilling their legal duty to monitor exposure in the workplace. Find out more on the biological monitoring and paint spraying page.
You need regular health surveillance such as lung function testing and skin checks. This is to identify early symptoms and signs of occupational asthma and dermatitis (skin rashes).

Examples that show other risks of working with isocyanate paints.

Bodyshop owners or managers

Spraying 2-pack isocyanate paints creates fine, invisible, airborne mist that can cause occupational asthma.
It spreads through the air like smoke.
Your spray booth or room takes time to clear of fine paint mist.
Measure the clearance time using a smoke or fog generator, clearly mark it on the entrance door(s) and make sure everyone who uses the booth or room knows what to do. For information on smoke generators and advice on how to conduct a clearance time measurement visit measuring paint spray booth clearance time.
Make sure the booth or room runs at slight negative pressure so that if there are any leaks, air is drawn into the booth or room rather than paint mist leaking out into the workshop.
Make a list of simple daily and weekly checks to be done in the booth or room, appoint someone to do them, record the findings and act if things are wrong.
Check exposure is properly controlled by arranging for the analysis of urine samples of vehicle paint sprayers. Find out more on the biological monitoring and paint spraying page.
Arrange regular health surveillance for those potentially exposed to isocyanate paints such as sprayers. For more information on health surveillance for occupational asthma see HSE guidance publication Health surveillance for occupational asthma (G402).
Use the COSHH paint spraying and allied tasks and other published advice to help you reduce exposures to isocyanates.

The research report on ‘An automated system for indicating spray clearance times of MVR spray booths and rooms - RR742’ describes the design and assembly of a device consisting of a timer switch, programmed with the clearance time, which is triggered by a sensor that detects when the spray gun is turned on and off.

2 types of sensor are evaluated and recommendations made for different operational setups. The system is relatively inexpensive and can be retrofitted to existing spray booths or rooms.

Further information on protecting yourself from the risks of isocyanate paints

We have more information on protecting yourself from the risks of isocyanate paints:

Examples of risks from working with isocyanate paints

Here are some real-life examples that show the risks of working inappropriately with isocyanate paints.

When workers in a large bodyshop complained of paint smells and tight chests, HSE measured their isocyanate exposure by biological monitoring. It was found that everyone in the bodyshop was exposed to isocyanate. The most highly exposed person being the receptionist. The downdraft spray booth filters were clogged and the over-pressure sensor had failed. The booths were becoming pressurised, especially during baking, and were leaking badly. They had never been thoroughly examined or tested.
An MVR paint sprayer worked for 10 years painting commercial vehicle bodies. They worked in a spray space and wore air-fed breathing apparatus. However, after spraying they would routinely flip up their visor to check on paint coverage and quality, allowing no time for the fine (invisible) overspray mist to clear. The first indications that something was wrong was when they started to suffer a tight chest overnight. Neither the sprayer or their GP made the connection between the paint sprayer’s asthma and exposure to isocyanates at work. They soldiered on until they could no longer work in the industry as they were unable to walk more than 20 yards before they needed to stop and rest.
A motor mechanic wore an ori-nasal filtering half-mask respirator when they started using 2-pack isocyanate paints in a spray space. Within a few months they found they were wheezing in the evenings after work and had a cough. They thought they were getting flu. After 2 years they had an acute asthma attack and was hospitalised. They are now registered disabled. They get asthma attacks triggered by non-specific air contaminants such as the smell of gloss paint or diesel fume or even just cold air.
A small bodyshop spraying isocyanate paints constructed its own spray room without help or advice from a specialist, such as a ventilation engineer. Not only did the sprayroom leak into the adjacent vehicle preparation areas, it also contaminated the air in the factory unit next door. HSE prohibited the process and the business ceased to trade.