We have been led to believe that the causes of air pollution in Malta come either from the now defunct Marsa power station or from the BWSC power station at Delimara.

That our towns, especially in the Grand Harbour area and in the South of Malta, that our populations, that many persons suffer from respiratory problems is a proven fact.

But like many crucial areas of national importance, everything gets sucked into partisan politics and the reality gets misted over.

We all thought, due to the partisan spin, that air pollution was due solely to the two power stations, the old one in Marsa and the BWSC plant in Delimara.

But there exist data (and this has been available scientifically for years) that show that air pollution in Malta is more due to that coming from the extraordinarily dense traffic pollution in many towns. There exists data that shows certain traffic nodes, such as Msida, and Fgura, that have a high air pollution. This is ascribable more to traffic than to power stations emanations which, in the case of Msida for example, are at some distance.

Successive governments have tried to curb this pollution by decreasing the number of cars with high pollution quotient by trying to get the Maltese to buy only new cars. But that strategy was undermined by a new twist that enabled massive importation of used cars. One principal reason for the change of public buses was precisely to cut down on the polluting buses and replacing them with clean buses.

During the public consultations with regards to the BWSC plant, it was pointed out that yet another source of pollution was sand from the Sahara. All this was backed up by scientific data.

We have now been informed of yet another source of pollution: the local NGO BirdLife has teamed up with NABU (BirdLife Germany) and other international partners to point out the pollution that comes from ships in harbours.

As this paper reported last week an exercise in air pollution measurement was carried out last week in Valletta and Birgu, which showed high concentrations of ultrafine particles in the ambient air during the time ships were transiting through the Grand Harbour.

Measurements revealed concentrations 80 times higher than clean air levels expected of areas not exposed to any pollution sources. Ultrafine particles are known to be a major risk to human health as they trigger severe heart and lung disease.

The NGOs will work towards raising awareness in Malta and the Mediterranean about air pollution from cruise ships, with the aim of establishing a Sulphur Emission Control Area within the Mediterranean.

Such an emission control area at sea would improve air quality by demanding that all ships operating within the Mediterranean use cleaner fuels.

It came as a total surprise to learn that ships use the notorious heavy fuel oil, about which we heard everything during the BWSC debate but little or nothing with regards to the cruise liner industry.

The emissions diminish the function of the lungs and increase the risk of cardiovascular disease. Some of them like black carbon, contribute to climate change. High concentrations of ultrafine particles in cities are responsible for the death of elderly people and people with poor health conditions.

Now cruise shipping movements in Malta have increased by almost 16% over the past six years with 280 cruise ships in 2010 and 324 in 2015 berthing at Valletta Cruise Port. In 2014, cruise ship passengers stood at 471,554 for the year, a rise of 9.3% in comparison to 2013.

Accompanying the BirdLife press release came a photo (see below) of a cruise liner belching black smoke out of its funnels.

Something has already been done: By July 2010 revised and more stringent regulations were enforced with significantly tightened emissions limits.