HSE Guide: Spray Painting Using Isocyanate-Based Paints

LEVCentral Expert Commentary

SMART (Small and Medium Area Repair Technique) repairs have become increasingly popular within the motor vehicle repair industry because they offer a fast and cost-effective method of repairing localised paint damage. However, the smaller scale of these repairs should not be confused with lower health risks.

INDG473 was produced by HSE to help employers, franchise operators, managers and technicians understand the controls required when carrying out SMART spraying operations. The guidance recognises that many SMART repairs are undertaken outside traditional spray booths and often in mobile or temporary working environments. This creates unique challenges when attempting to control exposure to paint mist, solvents and isocyanates.

A key message throughout the guidance is that SMART repairs must remain genuinely small-scale. Where larger quantities of paint are used or spraying times increase significantly, alternative controls such as a properly designed spray booth or spray room may be required. The distinction between SMART spraying and conventional spraying is therefore determined by exposure control rather than simply by the name of the process.

For LEV professionals and occupational hygienists, the document provides a useful reminder that effective exposure control is not always achieved through fixed engineering controls alone. Work area selection, exclusion zones, respiratory protective equipment, work practices, health surveillance and biological monitoring all contribute to protecting workers from occupational asthma and dermatitis.

Source Document

View Original HSE Guidance

Source: Health and Safety Executive (HSE)
Document Type: COSHH Guidance
Status: Current 2026
Last reviewed by LEVCentral: June 2026

Key Learning Points

SMART repairs involve spraying relatively small areas of a vehicle surface.
Some SMART repair paints and lacquers contain isocyanates which can cause occupational asthma.
Effective respiratory protective equipment is essential during spraying activities.
Other people should be kept away from the spraying area.
Work areas should be carefully selected and controlled to minimise exposure risks.
Exposure control measures must be proportionate to the quantity of material used and the duration of spraying.
Health surveillance and biological monitoring should be considered where isocyanate-containing products are used.
Larger or more extensive spraying activities may require a properly designed spray booth or spray room.
COSHH risk assessments remain essential even where SMART repair techniques are used.

Further Resources

Recommended Learning

Thought Leadership

One of the most common misconceptions surrounding SMART repairs is that because the repair is small, the risk must also be small. INDG473 challenges this assumption. Isocyanate exposure is determined by the nature of the material and the way it is used, not simply by the size of the repair.

For duty holders, the guidance reinforces an important principle: exposure control should always be based on risk assessment and evidence, not convenience. Whether work takes place in a fixed bodyshop or at a customer’s premises, the objective remains the same—prevent exposure, protect health and demonstrate that control measures are effective.