From E. A. Mallia

I find Albert Bezzina professed “disappointment” with my response, dubbed by him a “Talibanesk” banishment from Nuristan (the land of light) into the outer darkness (TMIS, 14 October); and appreciation of Dr G. Debono’s response (TMIS, 7 October), “written in the spirit of debate”, puzzling if not contradictory.

As far as Bezzina’s main lines of argument are concerned, the responsibilities of the construction industry and the public bus service for the major part of diesel emissions; and of our vehicle taxation system for hindering “a newer and cleaner vehicle fleet” – my response was identical to that of George Debono.

Technical fixes (newer cars, Euro V diesels, use of “undiluted” diesel fuel by everyone) are unlikely to solve our problem, the root cause of which is too many cars on our roads and too much car use. And that response clearly showed that our concerns went somewhat beyond those of Bezzina, much as they did in the case of bicycles and cyclists. In fact, one might be tempted to conclude that Bezzina’s “appreciation” had more than a hint of “medical mafia” about it.

Incidentally, between 2000 and 2006, the proportion of cars in the lowest engine capacity bracket took a nosedive, while all the other brackets, including cars of over 2 litres, showed proportional increases. The increasing popularity of diesel cars, at a time when the diesel/petrol price differential was still substantial, contributed to this. Of course, the total number of vehicles - and most specifically cars - on the road continued to climb.

A final point on diesel pollution: the black smoke contains relatively large carbon particles that can be stopped in the nasal passages. The real damage is done by the invisible small particles that are fine enough to penetrate deep into the lungs. But both fine and coarse particles carry PAHs (poly-aromatic hydrocarbons), known to be generally detrimental to health and recently connected with increased incidence of bronchitis in young children.

However, there was one pollutant left unmentioned by both Bezzina and Debono: low-level ozone, produced by the action of strong sunlight on unburnt fuel from petrol engines – conditions which occur in slow moving traffic during spring and summer. Ozone, an invisible and relatively odourless gas, is a strong irritant of the mucus membranes and an asthma trigger. An excellent demonstration of ozone formation can be seen in the real time measurements carried out by MEPA in St Anne Street in Floriana on car-free day in September 2006. The lesson was very clear: fewer cars and less use.

E. A. Mallia,

ATTARD