Wind direction multiplies pollutants in Mahon

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We have studied how the direction of the wind affects the measurements of the pollutants, and show that the winds from the north increase the concentrations of oxides of sulphur and nitrogen by 4 to 8 times. When the wind comes from the direction of the Central Electricity Power Station, these pollutants go as far as the town of Mahon. A change to the criterion of the production of electricity to that which prioritises the health of the public is urgently required.

Currently, the cheapest fuels are used principally, despite the fact that they are also the most harmful to health. A priority would be to change the fuel on the days when the wind is from the north and this is the least that can be asked in order to reduce the episodes of the highest concentration of these oxides.

Measurements of air quality taken at points near to the port of Mahon have been compared on various occasions with different directions and velocity of wind at any given time. The conclusion is that winds coming from the direction of the Central Power Station, and to a lesser extent due to any presence of large boats docked in the Port, increase the concentrations of SO2, NO2 and NO on the town.

When the wind is from the north, the average concentration of SO2 and NO2 is raised four times above the annual average and that of NO up to eight times. The concentrations rise with wind speeds up to some 40 km/h, from which they fall. The wind does not correlate with concentrations of ozone or particulates of PM10. We do not have information on the particulates pm2.5, which are smaller and dangerous, and which originate from fuels.

The Central Power Station of Mahon Port mostly uses old engines that run on fuel oil, dating from before modern ones that operate with diesel, simply because fuel oil is much cheaper despite being more polluting. This criterion needs to be changed.

Maximum concentrations of SO2, NO2 and NO have been observed during episodes of the north wind. Although the concentrations do not exceed the thresholds allowed by current legislation, based on the indices of air quality from the Ministry of Ecological Transition and the Demographic Challenge (BOE no 242 DE 10/09/2020) in 2019 there was only a total of 23 time slots in which the air quality in Mahon was in the regular category.

During the most polluting episodes of the year, the pollution level of SO2 in 24 hours far exceeded that recommended by the WHO. A similar resolution of the Ministry of Ecological Transition states that in cases where the quality of air is classified as regular the probability is that it does not generally affect the public but it can represent a moderate risk for certain groups that are more vulnerable. Furthermore, although the majority of cases do not exceed the legal thresholds established for a certain atmospheric pollutant, it is necessary to take into account the synergistic effect that exposure can have from multiple pollutants, a little studied effect these days. A change in fuel during the episodes of north wind is the least that can be demanded.

Work has been carried out with data from 2019. The start of functioning in the Central Power Station in 2020 with cooling of the towers with purified water allowed a reduction in the emissions of nitrogen oxides from the diesel engines, but not the fuel oil of sulphur oxides. Another reason to prioritise using diesel engines rather than fuel-oil ones. We also miss the warning systems for advising the public of danger times. We have repeatedly asked for information panels showing the pollution levels to be made available to the public.

The aim in a few years ought to be to increase significantly renewable energies and efficient consumption, so as to reduce the working of the Central Power Station in Mahon Port, that should also use gas instead of fuel. However, until this happens, there are actions that can be taken to reduce the health risks for those who live round the port of Mahon. The priority of public health should be the guide for these actions.