Chemicals expert Prof Alfred Vella admitted today that no direct comparison had been made between particles he had examined as part of his study on the black dust problem, and particles collected directly from Marsa power station.
Prof Vella was replying to repeated questioning by Nationalist MP Franco Debono who asked if there had been such a comparison/confrontation between the particles collected from Fgura and elsewhere, and others which could be picked up from Marsa.
Prof Vella said that during the period of his study there had been no catastrophic dust falls. The particles which had been studied came from dust which fell ordinarily every day. The samples were collected all over Malta and part of Gozo as part of a study on the impact of fireworks.
The particles he had studied were too small for chemical study, but the Marsa power station was identified as the likely source of the 'black dust' because of the shape, colour size and distribution of the dust south east of the power station in view of the prevailing North-Westerly wind.
Furthermore, direct comparisons between the particles had already been done in the past.
Speaking at a meeting of a parliamentary committee, Prof Vella said he would recommend that a direct comparison be made if there was another case of a large amount of black dust appearing. However it was important that the samples were professionally collected and not contaminated.
Earlier, Labour MP Joe Mizzi asked if further studies needed to be made on the samples, such as the organic content and the fuel used.
Jesmond Mugliett (PN) asked if the methodology used in the latest study was different from past studies. Had the samples been adquate?
Prof Vella said the study did not collect samples after 'catastrophic dust falls' but the big black particles were noted within samples collected for fireworks studies which, he said as an aside, showed massive degradation of the environment caused by fireworks.
The size and nature of the black dust showed this was not the sort of dust that came from traffic emissions. These were bigger particles, and the distribution of their fall pointed the source directly to the Marsa power station.
When it was pointed out to Prof Vella that Enemalta had contested his findings, pointing to the composition of the particles, Prof Vella said that this was like a case where he was saying that he had seen a man walking by, but Enemalta was disputing that because he had not produced the DNA.
The only credible source of the black dust was the power station as confirmed by the enormous concentration on church steeples and other buildings south east of the chimneys. His study had analysed dust which fell every day and which included black dust, and one could, therefore, safely conclude that a catastrophic fall - of the sort which left a layer of dust overnight - would come from the same source.