Two workers from an electroplating factory had symptoms that suggested occupational asthma. The diagnosis was confirmed by lung function tests in the workplace. But the cause was unknown.
Then a worker produced a safety data sheet describing a lacquer containing isocyanates. This lacquer was used to coat the silver-plated goods and then cured in an oven.
HSE confirmed that isocyanates were being used, and the employer was exceeding the workplace exposure limits. Testing with cheap smoke tubes showed contaminated air from the ovens was reaching the workers.
The employer installed fume extraction. This dramatically reduced the levels of isocyanates in the working environment.
One of the workers took early retirement on medical grounds, with compensation for occupational asthma due to isocyanates. The second worker had to change employment and applied for compensation.