It is dismaying to see how doggedly government departments defend their patch when faced with criticism or facts which they perceive as unwelcome. They are also so uncannily quick to react with evasive answers or to commission expensive reports in the hope that the problem will go away in the meantime.
Alfred Vella has now added to the controversy by pooh-poohing the whole matter (Black Dust ‘Not A Health Concern’, September 12) with his sweeping reassurance that dust particles (over 50 microns in diameter) are not dangerous to health “because they cannot be inhaled”. This is quite unbelievable. Such particles can easily be inhaled; the only difference is that they are unlikely to penetrate sufficiently deep into our lungs and endanger our health to the same extent as fine particles (of around 10 microns or less).
More important is this: Basing conclusions on size of visible dust particles alone does not in any way mitigate or exclude health hazards of other associated pollutants which are invisible. In fact it is standard practice to regard the amount of soot or black smoke in the environment as a reliable indicator of the degree of pollution with fine particles and other hazardous combustion emissions. Since the source of the black dust is almost certainly an internal combustion engine, then it must be assumed that invisible clouds of fine particles, including toxic micro-particles of less than 10 microns, are also being emitted from the source that is sending black dust into the air.
This would especially be the case if the emitter of the black dust is an engine that runs on heavy fuel oil because fine particulates so produced are difficult to remove effectively by means of filtering or precipitators.
Fine particles tend to remain suspended for long periods in the ambient air we breathe and, being invisible, nobody worries about them. But it is precisely these fine particles (10 microns or smaller) that should be the major source of concern – rather than visible dust. They are dangerous because they penetrate furthermost into the lung and become trapped to cause respiratory disorders, especially asthma or lung cancer years later. Finer particles may even directly cross into the bloodstream through the lung or respiratory passages and predispose to heart attacks and other illnesses.
Unfortunately, the burning question (pun unintended) has mostly centred on the source of the black dust. This has diverted attention away from the implication that dangerous fine particles are also being emitted from the same source.
In any case, it is unacceptable to conclude that this dust “poses no threat to health” and is “more of a nuisance than anything else” in the absence of scientific or epidemiological data. Malta’s population is anyway too small to permit a meaningful epidemiological study which might have given an answer; neither has there been any toxicological testing of this black dust or analysis of the nature (size of particles) of the dust at source. Large scale studies over long periods of years, such as the landmark study by the American Cancer Society, have consistently shown that particulate pollution poses a serious threat to health, even at low concentrations.
After the most searching scrutiny of the data and reanalysis by more advanced statistical methods, WHO and other leading health bodies accepted the results as irrefutable evidence that particulates are associated with early death due to a number of causes including cancer. WHO also indicated that the findings applied to all countries and situations. The statement that the black dust does not present a health hazard is therefore a reckless assessment which is merely speculative; it also only looks at the tip of the iceberg. More importantly, it fails to address the serious implication that the presence of this dust is a sure sign of simultaneous emission of fine particles at source, to which the population is exposed.