Pollution from cars, heating and industry is among the main causes of the degradation of cultural heritage.
This is what an ENEA report highlighted, which demonstrated the harmful effects of the main air pollutants (nitrogen oxides and PM10) on three UNESCO heritage sites: the Royal Palace of Caserta, the Cathedral of St. Domnius in Split (Croatia) and the Würzburg Residence (Germany). “The Royal Palace of Caserta suffered the greatest damage, where we calculated for each year a surface corrosion rate higher than the target value set for 2050 (6,4 microns per year), which must not be exceeded if we want to preserve the health of the historic royal residence, a destination for 700 visitors every year”, explains Teresa La Torretta, researcher at the ENEA Air Pollution Laboratory and co-author of the report together with her colleague Pasquale Spezzano.
The air pollution measuring station near the Royal Palace of Caserta showed high and constant values of nitrogen dioxide and fine particulate matter (PM10), remaining just above 20 micrograms per cubic meter.
“The Royal Palace is located in the heart of the city and is therefore particularly exposed to air pollution caused by industry, heating and road transport, although there is no shortage of natural sources far from the city such as marine aerosol and Saharan sand which cause an increase in PM10 particulate matter especially in southern Europe”, adds La Torretta.
From a comparison of the state of health of the three UNESCO sites examined, those of Würzburg and Split reveal values of degradation speed of the external surfaces below the 'safety threshold'. An important factor in determining the differences between the three sites is represented by the local weather-climatic conditions (temperature, rainfall, relative humidity) which play a role in enhancing the aggressiveness of the pollutants and, consequently, in increasing the corrosion of the stone surfaces. In the study period considered (2015-2019) the three sample cities recorded a general decrease in emissions in all major sectors, with an exception regarding nitrogen oxides (NOx) from maritime transport in Split (+16% in 2019 compared to 2015). In fact, in the same period a slight reduction in the pollutants of interest in the air (nitrogen dioxide and PM10) was found.
However, it should be noted, for example, that nitrogen oxide emissions in Caserta (2779,26 tonnes in 2019, main emitters are industry and road transport) are approximately three times higher than in Würzburg (868,82 tonnes, main emitter is road transport) and almost double than in Split (1532,18 tonnes, main emitter is industry).
“Among the main measures that can be adopted, it would certainly be appropriate to implement policies to reduce city traffic by focusing on public transport, car-sharing and low-emission vehicles”, underlines the ENEA researcher.
The degradation of cultural heritage materials due to air pollution is significantly lower than 20-30 years ago when acidifying rainfall and air pollutants such as sulphur dioxide contributed to increased corrosion in urban areas.
“Today these pollutants have drastically decreased, even if in recent years the reduction has stabilized. However, the concentrations of nitrogen dioxide (NO2) and PM10 particulate matter have not decreased to the same extent, contributing to the degradation of monuments and to an increase in restoration and maintenance costs”, concludes La Torretta.
The study carried out by ENEA is part of the initiative “International Cooperative Programme on Effects of Air Pollution on Materials, including Historic and Cultural Monuments (ICP Materials)” of the UNECE Convention on Long-Range Transboundary Air Pollution (Air Convention). The UNECE Air Convention, adopted in 1979, provides a unique and binding regional instrument through which 51 Parties from pan-European Europe and North America cooperate to achieve reductions in emissions of the main pollutants.
In addition to causing the degradation of monuments, air pollution harms human health, as warned by the European Environment Agency report, which defines it as the greatest environmental risk to health in Europe, causing cardiovascular and respiratory diseases that reduce life expectancy and, in the worst cases, preventable deaths. Despite constant improvements, exceedances of air quality standards are common throughout the EU, with concentrations well above the latest recommendations of the World Health Organization.
On the subject of air pollution, ENEA provides the “MINNI” system, which produces 3-day hourly maps of pollutant concentrations, in particular fine dust, with a spatial resolution that in Italy reaches 4 km2, the size of a small municipality.
Article published on November 8, 2023 - 13:58
