Case Studies - Raising Awareness of Asthma Risks in Motor Vehicle Repair

Two-pack paints are used extensively in primers and lacquers
for repainting vehicles in the motor vehicle repair (MVR) trade. The properties of these paints make them ideal for vehicles but the presence of isocyanates in the paints presents risks to operators, especially during spray application. Spray mist and vapours containing isocyanates may cause or worsen existing asthma.

Larger companies use spray-painting booths designed for the purpose. These are equipped with ventilation systems to reduce worker exposure to the paint spray. Smaller premises tend to use ventilated rooms designated as “spray spaces”. Despite these control measures and the use of respiratory protective equipment, MVR paint sprayers are eighty times more likely to become asthmatic compared with the UK working population as a whole. Once people are affected their symptoms can be triggered by very low repeat exposures.

Over fifty MVR sprayers are diagnosed with occupational asthma every year and most have to leave the industry.

HSE asked HSL to investigate the use of two-pack isocyanate paints in MVR so that exposure routes could be better understood and more effective means of controlling exposure could be developed. The exposure of spray painters was measured during field studies and superimposed on video recordings of the tasks, thus identifying the activities causing the highest exposure to isocyanates. Working models of spray booths and spray spaces were constructed using information gathered in these surveys. These models demonstrate, in a very visual way, how air moves within the ventilated areas and the efficiency of removal of contaminated air.

An experimental spray space and robotic spraying system were then constructed at HSL to investigate a wide range of variables for comparison with field observations and measurements. This is providing a better understanding of the behaviour of paint spray aerosols during and after application and is helping in suggesting improvements to the design and operation of spray spaces and the working practices of sprayers.

The ventilation models and video images, together with the experimental results, are being used in a programme of Safety and Health Awareness Days organised by HSE for the MVR industry. At these events, sprayers and employers are given targeted information by a range of experts about the hazards and risks associated with spraying isocyanates and how to control exposure to prevent ill-health. A video presentation of an interview with a person affected by isocyanate asthma leaves attendees in no doubt about the impact the disease has on sufferers’ lives.

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