Two-pack isocyanate paint in a vehicle refinishing workshop
A vehicle refinishing workshop employs 12 staff, including four painters. Two enclosed spray booths were installed in 2015. The main paint system is a two-pack acrylic containing an isocyanate hardener; smaller areas are also sprayed with a zinc-rich primer. Between 20 and 30 vehicles pass through in a week, each taking 40-90 minutes of spraying. The booth extraction was last examined and tested three years ago, and there is no record of airflow testing. The workshop's COSHH assessment is a single paragraph written in 2016: it states that the booth has LEV, that staff wear masks and that the risk is low. In practice, painters wear disposable FFP3 dust masks, mix paint at an open bench, and clean spray guns in an open bucket of thinners. An experienced painter has reported wheeze and chest tightness that improves at weekends, and has had two days off work. He is 34 and has sprayed two-pack paints for nine years.
1. Critique the existing COSHH assessment against the requirement for it to be suitable and sufficient, identifying the specific failings.
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A suitable and sufficient assessment must identify the hazard, the routes of exposure, who is exposed and how, evaluate the adequacy of existing controls, and set out what further action is needed. A single paragraph cannot do this, and the following gaps are decisive.
- No task-level exposure analysis. Mixing, spraying, gun cleaning, booth cleaning and filter changing are separate tasks with different exposure profiles. The assessment treats 'painting' as one thing, so it cannot drive controls for the worst task - mixing hardener at an open bench, which produces vapour right at the breathing zone.
- Routes of exposure incomplete. It addresses inhalation only. Isocyanates also cause skin sensitisation and dermatitis through splashes during mixing, gun cleaning and suit removal.
- Existing controls assumed rather than verified. 'The booth has LEV' is not evidence that the booth works. The extraction is overdue for thorough examination and test (COSHH requires this at intervals not exceeding 14 months), and there is no airflow record, so containment may be failing.
- RPE is inappropriate. Disposable FFP3 respirators are particulate filters and do not stop isocyanate vapour. An A2P3 combination filter or air-fed visor is needed, fit-tested, with face-fit records. Stating that staff 'wear masks' gives false assurance.
- No comparison with the workplace exposure limit. The WEL for isocyanates is 0.02 mg/m3 as an 8-hour TWA (as NCO), with a 15-minute reference period of 0.07 mg/m3; the assessment never establishes whether exposure is anywhere near it.
- No health surveillance, although isocyanate work is exactly the activity that requires it.
- No review trigger. It predates the current paint system and has not been revised despite symptoms.
Conclusion: the document records a decision that was never made. It is not suitable and sufficient, and the symptomatic painter is the predictable consequence.
2. Apply the hierarchy of control to reduce isocyanate exposure in this workshop, justifying the order in which you would act.
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The hierarchy works from removing the hazard towards protecting the individual, and the justification is reliability: the further down the list, the more the control depends on human behaviour and the more it fails silently.
Eliminate / substitute. Review whether two-pack isocyanate is needed for every job. Clear-coat and colour work on older or low-value vehicles may accept a non-isocyanate system; pre-mixed or low-monomer products may be available; small repairs can be brush or aerosol-applied in an extracted enclosure rather than sprayed. This removes sensitisation risk entirely for those jobs, so it comes first even if it only covers part of the throughput.
Engineering controls. Repair and commission the booths and reinstate the thorough examination and test cycle with airflow records. Provide local extraction at the mixing bench and an enclosed gun washer instead of an open bucket. Put a dedicated, extracted area for filter changes.
Procedural controls. Segregate mixing from spraying; restrict spraying to trained, fit-tested painters; wet-clean rather than sweep; ban eating and smoking in the booths; specify suit removal sequence to prevent skin contamination; decontaminate before breaks.
PPE. Air-fed visor or A2P3 with fit testing, coveralls and nitrile gloves - as the last line, supporting the above, not substituting for it.
Health surveillance. Pre-placement respiratory questionnaire and baseline spirometry, then an annual questionnaire with spirometry and skin checks; refer any abnormality. Records must be kept for 40 years because sensitisation can develop years after exposure.
Reasoning: PPE and RPE are the controls most easily defeated by a hot day or a rushed job, and respiratory sensitisers can cause lifelong asthma after a single high exposure, so engineering and substitution carry the weight.
3. Explain what you would do now about the symptomatic painter, including legal duties and reporting obligations.
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Immediate action comes before paperwork. Remove him from all isocyanate work at once and do not allow return until a doctor has advised. Continued exposure in a sensitised person can worsen asthma, sometimes severely, and the duty to protect health is immediate and unconditional - it does not wait for a diagnosis.
Health referral. Refer him to occupational health or, failing that, advise him to see his GP, and tell the GP what he is exposed to. Give him the relevant safety data sheet. Record the referral and the advice given in his health record. The employer must not read the clinical findings; the occupational health professional reports only on fitness and restrictions.
Reporting. Occupational asthma is a reportable disease under RIDDOR where it is diagnosed by a doctor and the person works in a prescribed activity. If a diagnosis is confirmed, report it. Do not report on suspicion alone; record the decision and the date either way.
Investigate the workplace, not the man. His symptoms point to control failure. Commission air monitoring for isocyanates across mixing, spraying and gun cleaning, bring the booth test forward, check RPE type and fit, and observe the actual tasks. The results should drive the revised assessment.
Wider duties. Inform and consult the other painters and their representatives about the hazard and the changes; the other three painters need the same health surveillance, because early changes are often asymptomatic. Review the assessment, retrain, and verify that the new controls are used by supervision rather than assumption.
Reasoning: the individual case is a sentinel event. Handling it well means protecting one person and using the signal to fix the system for the other three.