The black dust plaguing some localities in the south was less of a health hazard than car fumes, according to respiratory doctor Martin Balzan.
The gritty dust particles - covering cars, roofs and backyards in Fgura, Paola, Tarxien, Zabbar and Zejtun - are too big to enter the respiratory airways and less harmful than the invisible exhaust fumes inhaled into people's lungs.
In 2001, hospitalisation rates from asthma in Fgura were three times the average in other localities. But a study carried out by Dr Balzan found this was not correlated to the power station emissions but to vehicles passing through the main road.
This did not mean the dust was of no concern, said Dr Balzan, who lives in the area.
"Notwithstanding the fact that it does not have an effect on asthma, it is not desirable to have such chemicals in the ecosystem," he said, adding that certain metals were carcinogenic and could have long-term health effects if they entered the water table or the food chain.
Earlier this week, Enemalta insisted the black dust was not spouting from the Marsa power station, and tests by the Malta Environment and Planning Authority to determine where it was coming from are still underway.
But locals are finding it hard to accept Enemalta's statement and even Dr Balzan suspects the problem was caused by a malfunction of the power station filters.
Fgura deputy mayor Anthony de Giovanni said the turbines lacked some of the necessary filters.
Fgura resident Rudolf Degiorgio said the dust was probably being emitted when the power station flushed its chimneys during night-time. "Every morning my light grey car is completely covered in dust, while the roof garden, which we would have swept the night before, is also full of black dust," he said.
The father-of-two voiced concern about the health effects of the dust, adding that he started suffering from hay fever since he moved to Fgura in 1998, while his nine-year-old son suffered from allergies.
A spokesman for Enemalta was asked whether the filters were working properly and whether any tests had been carried out to ensure there were no faults but no replies were forthcoming at the time of going to press.
The corporation said earlier this week that emissions had remained consistent over the past six months and were well within the stipulated limits.
Meanwhile, the Malta Environment and Planning Authority will be evaluating dust collected from roofs with samples taken from the power station's chimneys. Asked whether the dust had pushed emissions beyond EU-accepted levels, an authority spokesman said this was not the case. "It is more of an inconvenience than a health risk," he said.
Labour Party environment spokesman Leo Brincat yesterday held a press conference urging the government to identify the source of the dust and to shoulder its responsibility.
He said automated measuring systems should be immediately installed at the Delimara and Marsa power stations to calculate the levels of particles in its emissions.
Records of these emissions should be published regularly online.