The Maltese islands are exposed to a lot of wind, coming from practically all directions and for most times of the year.
Malta’s central position in the Mediterranean makes us prone to all kinds of dusts- Alan Pulis
A thorough statistical analysis by Galdies (2011) describing the climatology of Malta estimates the mean annual wind speed during the period 1961-1990 (a standard 30-year period that is usually taken as benchmark for the purpose of climate studies) at 8.8 knots or circa 16.3km/hr, the data revealing considerable variation in monthly averages.
January until April is the windiest time of year, with July and August typically being the calmest months. The most common wind direction is the north-west, followed by the west and south-westerly winds.
Perfectly calm days are very infrequent on our islands and it transpires that all kinds of air pollution across Europe and North Africa will always concern us.
Wind is not just moving air; wind is also a vector that carries with it a lot of material – and not just dust – from elsewhere. We live in a dusty place and, without wanting to sound as if the dust pollution impact from our oil-fired power stations can ever be downplayed, the source of dust to which we are exposed go far beyond Maltese shores.
The European Environment Agency has recently published Technical Report No. 10/2012 tackling the issue of particulate matter from natural sources and how this kind of dust affects the implementation of Directive 2008/50/EC on Ambient Air Quality and Cleaner Air for Europe (the CAFE Directive).
The directive, the outcome of a relatively recent major overhaul in the air quality regime under EU law, remarkably provides that member states may subtract the contribution of natural sources before comparing the relevant ambient air concentrations for the various pollutants, including particulate matter, from the legally binding limit values.
In other words, the legislative framework enables a mechanism that allows for quantifying the extent of anthropogenic pollution by eliminating the background “noise” that will always interfere in the collection of air pollution data due to pollution from natural sources.
Mount Etna eruptions in 2001 followed by others in October 2002 and early 2003 have resulted in spectacular ash plume emissions that have been clearly identified by satellite imagery as extending over a vast distance across the Mediterranean, practically engulfing our islands.
Back then, when residents from various localities were prompt to complain with Enemalta about ominous black dust on the streets, roofs and backyards, our energy corporation must have had a hard time trying to convince them they had nothing to do with it. Such a singular event, however, in all its complexity, bears so much when the implications of Directive 2008/50/EC are taken into account.
EEA Technical Report No. 10/2012 identifies four main categories of dust that may be subtracted for the purpose of implementing the provisions under Directive 2008/50/EC: wind-blown desert dust, sea spray aerosols, particulate matter from volcanoes and seismic activities and the particulate volume emitted from wildfires.
In chemical analysis lies the key. It is well-known, for example, that dust from heavy fuel oil combustion such as that occurring in power stations, is rich in heavy metals, particularly nickel and vanadium.
On the other hand, dust from Africa, which reaches our islands from the Sahara, is basically made up of silicates and carbonates that may not be so easily distinguished from the white dust released from, say, local quarrying sites.
Sea spray is mostly sodium chloride whereas elucidating the nature of particulates from volcanic eruptions can be a far more complex matter: volcanic dust tends to react in the air with the sulphur dioxide that is conjointly released, producing heavierdenser secondary particles that ultimately take the form of the black dust matter that was reported to Enemalta when the 2001 Mount Etna events took place.
Wildfires, a phenomenon that has become a frequent occurrence across Europe, especially during the hot summer months, are identified as a source of the more noxious PM2.5, possibly the most harmful of particulate matter types.
In this regard, an interesting issue arises: to what extent should pollution from wildfires be considered natural and therefore subtracted as under the remit of the directive when arson is often the case?
The salient conclusion from EEA Technical Report No. 10/2012 reads rather bleak: the analysts could not detect a common Europe-wide strategy on how to deal with emissions from natural sources and how this impacts, more precisely, in terms of air quality data submissions by member states under the directive.
Malta’s central position in the Mediterranean makes us prone to all kinds of dusts from both the European and African continental mainlands. We are probably the best suited European nation – a laboratory in its own right – that could serve as launch pad for an overarching EU strategy on dealing with natural dusts.
sapulis@gmail.com
Alan Pulis specialises in environmental management.