Nigel Grey, Director of Service at the instrumentation company Air Monitors (UK), has issued a warning concerning the appearance of sub-standard filters in the UK's network of particulate monitoring systems. He says "These filters are a poor quality imitation of genuine Thermo Fisher parts, and are damaging the quality and reliability of data from the UK's TEOM and TEOM/FDMS particulate monitoring systems."
Nigel's team of engineers are responsible for the maintenance of part of the UK's monitoring network and he says "we only use genuine Thermo Fisher filters because they are subject to a rigorous quality assurance system which ensures that they are symmetrical, constructed from the correct materials and manufactured to the finest tolerances."
Sub-standard, non-genuine filters are being imported and sold in the UK, and the Air Monitors engineers have found that they are causing poor monitoring performance that is characterised by noisy data, offsets and erroneous concentrations. The filters are probably being offered at very low prices, but Nigel says "the cost savings are minor in comparison with the costs of poor quality or rejected data, especially if the sub-standard filters result in reduced data capture."
The managers of Defra's automatic urban and rural monitoring network have already acted to remove all of these filters from the network. However, Nigel Grey says "If anyone else still has any sub-standard filters in use or in stock, we recommend that you return them to the company that supplied them, and request a refund or that they be replaced with genuine filters."