Two waste skips containing used glass fibre filters from a paint booth caught fire at a construction equipment hire company. The operator had the building evacuated. Black smoke rose into the air. The company suffered an estimated €300,000 in material damage and €50,000 in operating losses.

The drying of alkyd resin paint (evaporation of the water in the paint followed by oxidation of the paint itself) is exothermic. The filters, located under the grating in the booth, progressively become fouled with paint. After 150 hours of use, the fouled filters are placed in specific waste skips and new ones are fitted. As the lids on the skips are closed, oxidation occurs over several days. On the day of the fire, the weather was very hot. Compounding this was a mass effect due to the fact that the filters in the skips had been rolled up. The temperature inside the skips rose to the autoignition temperature of the paint residues trapped in the filters, igniting the fire. As the supplier had not given any information about this risk, it was not included in the risk analysis.

The operator took the following measures:

• it is working with the paint and filter suppliers on the causes of the fire and the measures to be taken;
• it now stores fouled filters in sealed metal drums to limit the supply of oxygen;
• these drums are now stored in a shaded area outside the facility;
• the waste collector systematically takes the drums away either the same day that the filters are placed in them or no later than the following day;
• it educated its employees on this safety issue.