Heatwaves and particulate matter increases: An Italian case study

Amongst extreme weather events, heatwaves are one of the most worrying phenomena because of their numerous social, health and economic impacts. Besides direct effects emerging from reduced thermal comfort, indirect synergistic effects also result from the concurrent air quality deterioration. So far, many studies have highlighted the association between heatwaves and high concentrations of tropospheric ozone in urban areas, all concerning the ozone budget affected by formation and destruction processes. On the other hand, the association between particulate matter enhancements and heatwaves is less known and investigated. This paper provides the detection and the analysis of this kind of events occurred in Bologna (Italy) in the period January-November 2023. The investigation points out the identification of 7 events, corresponding to the 25% of days investigated (85 out of 334). A multidisciplinary approach, including combined analysis of meteorological, physical and chemical datasets, as well as satellite and ground based remote sensing data, is used in this work to characterize a case study identified in the period from 11th to 20th July 2023. The analysis highlights the role of the African anticyclone as responsible of the blocking pattern causing both the heatwave and the dust advection towards the study site, as evidenced by the analysis of measurements of PM10 concentrations and of the aerosol particle size distribution. Given the significant public health implications of concurrent heatwaves and particulate matter enhancements, improved understanding is critical to inform mitigation strategies, thereby reducing related morbidity and mortality.