Guidance on working with 2-pack isocyanate paints


Paints containing isocyanate are used extensively in MVR as almost all motor vehicle repair 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.

Spraying 2-pack isocyanate paints is the main cause of occupational asthma in the UK and, for years, vehicle paint sprayers have been the group most at risk. MVR paint sprayers have about a 90 times higher risk of getting asthma compared with the UK working population. Every year around 50 sprayers are diagnosed with isocyanate asthma and most have to leave the industry. Other workers in bodyshops are also sometimes affected eg maintenance personnel, managers and others who work in close proximity to spray booths/rooms. This spray mist containing isocyanate may also worsen existing asthma. Once people are affected even very low exposure levels can trigger an attack. Significant skin contact with isocyanate hardeners may cause dermatitis.

Over a number of years HSE have worked with industry representatives to explode the myths and explain why even the best air-fed visor can fail to protect people. Over 2000 people involved with vehicle paint spraying have attended free workshops up and down the country to find out how they could carry on using isocyanate paints safely. The ground-breaking training material used at these Safety and Health Awareness Days has now been made freely available on the MVR webpages.

Below are some key tips for vehicle paint sprayers and owners of motor vehicle repair bodyshops.

Vehicle paint sprayers

Bodyshop owners / managers

Further information

Case studies

  • 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. He worked in a spray space and wore air-fed breathing apparatus. However, after spraying he would routinely flip up his visor to check on paint coverage, quality etc allowing no time for the fine (invisible) overspray mist to clear. The first indications that something was wrong was when he started to suffer a tight chest overnight. Neither the sprayer nor his GP made the connection between his asthma and exposure to isocyanates at work. He soldiered on until he could no longer work. Effectively he was unemployable because he was unable to walk more than 20 yards before he needed to stop and rest.
  • A motor mechanic wore an ori-nasal filtering half-mask respirator when he started using 2-pack isocyanate paints in a spray space. Within a few months he found he was wheezing in the evenings after work and had a cough. He thought he was getting flu. After two years he had an acute asthma attack and was hospitalised. He is now registered disabled and is a respiratory cripple. He gets 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. The business ceased to trade.
Updated 2022-11-09