This shows a procedure called video-visualisation. An operator (wearing an air-fed visor) is shown spraying a vehicle. At the same time the concentration of isocyanates surrounding the sprayers visor is measured and recorded from second to second using specialist equipment from the Health and Safety Laboratory. These measurements are then superimposed on a graph showing isocyanate concentration on the Y axis and time across the X axis.
There is also a small box above the graph that shows the numerical concentration from second to second. The video plays in a screen above the graph and it is possible to show what activities cause the highest and lowest exposures.
The graph of the spraying activity shows a series of peaks and troughs. Although not shown on this clip, some of these peaks are high (nearly 7,500). When averaged over the spray job, the average concentration in the operator's breathing zone is 1067 microgram/cubic metre. In other words, spraying with a conventional gun (or if the HVLP gun is set up incorrectly) can increase airborne concentration of isocyanate 1.5 to 2 times compared to HVLP working properly.