PL7

The RHAPS (Redox‐Activity And Health‐Effects Of Atmospheric Primary And Secondary Aerosol) project was launched in 2019 with the major objective of identifying specific properties of the fine atmospheric aerosol from combustion sources that are responsible for toxicological effects and can be used as new metrics for health‐related outdoor pollution studies. Here, we will present the overall methodology of RHAPS, we introduce the phenomenology and the first data observed. A comprehensive physico‐chemical aerosol characterization has been achieved by means of high‐time resolution measurements (e.g., number size distributions, refractory chemical components, elemental composition) and low‐time resolution analyses (e.g., oxidative potential, toxicological assays, chemical composition). Preliminary results indicate that, at the real atmospheric conditions observed (i.e., daily PM1 from less than 4 to more than 50 μg m−3), high/low mass concentrations of PM1, as well as black carbon (BC) and water soluble Oxidative Potential (WSOP,) do not necessarily translate into high/low toxicity. Notably, these findings were observed during a variety of atmospheric conditions and aerosol properties and with different toxicological assessments. Findings suggest a higher complexity in the relations observed between atmospheric aerosol and toxicological endpoints that go beyond the currently used PM1 metrics. Finally, we provide an outlook to companion papers where data will be analyzed in more detail, with the focus on source apportionment of PM1 and the role of source emissions on aerosol toxicity, the OP as a predictive variable for PM1 toxicity, and the related role of SOA possessing redox‐active capacity, exposure‐response relationships for PM1, and air quality models to forecast PM1 toxicity.

How to cite: Costabile, F. and the RHAPS team: On the Redox‐Activity and Health‐Effects of Atmospheric Primary and Secondary Aerosol, 17th Plinius Conference on Mediterranean Risks, Frascati, Rome, Italy, 18–21 Oct 2022, Plinius17-63, https://doi.org/10.5194/egusphere-plinius17-63, 2022.

Climate change is expected to raise the threats to human health. The effects of temperatures on excess of mortality, for exposed populations, can be amplified by the simultaneous presence of air pollution.

Using Distributed Lag Nonlinear Models with delayed effects, we assess the combined short-term impact of temperature and air pollution (PM10, O₃) for Milan and Rome, the latter located at the center of the Mediterranean basin. Relative mortality risks (RRs) are estimated for the city population as a whole and the most vulnerable group of people (over the age of 85), for the historical decade 2004-2015 and for the future (2050), assuming climate and air pollution scenarios consistent with the representative concentration pathways RCP2.6 and RCP8.5. The daily mean temperature (T) and the daily apparent mean temperature (AT) exposure variables are used to proxy the effects of climate change; the MDA8 (maximum daily 8-hour average concentration) indicator for O₃ and the daily mean of PM10 characterize, instead, past and future air pollution effects. The minimum mortality temperature (T_mm), which is city specific due to human adaptability to the local climate, is defined and inferred for both cities and age groups, together with exposure-response functions for each exposure variable.

Results on past mortality show lower RRs for Rome along the whole year and a larger influence of temperature rather than air pollutant on short-term mortality. Specifically, attributable deaths are mainly associated with low temperature conditions (T<T_mm) and increase when considering the older age group. As regard of air pollutants, their combined influence sum up to those of temperature with a seasonal connotation: while PM10 affects the risk values mainly in association with low temperatures, O₃ exerts its greatest effect especially in conjunction with high temperatures.

RRs projections to 2050 confirm that Rome is the least affected city with a smaller fraction of total deaths attributable to climate change and air pollution. The effects of global warming is captured by a double-sided effect: a decrease in the cold-related mortality burden and a rise in the attributable mortality due to increasing temperatures. However, the latter effect partially offsets the relief in the health burden achieved from the former one. This substitution effect between cold- and warm-related mortality is more evident in the RCP8.5 scenario and for the 85+ age group.

Concluding, the results suggest that a more rigorous and internationally coordinated climate action, implying more stringency in related policies, can lead to significant co-benefits: in addition to reducing the future health burden, containing the air pollution implications, and achieving climate objectives, health costs and loss of life can be also reduced. Indeed, when the effects of climate change and air pollution are contained with climate policy action (RCP2.6) the number of fatalities could decrease by 8 times in Rome and 1.4 in Milan, compared to historical values.

How to cite: Michetti, M., Gualtieri, M., Anav, A., Adani, M., Benassi, B., Dalmastri, C., D'Elia, I., Piersanti, A., Sannino, G., Zanini, G., and Uccelli, R.: Past and future health burden: the impact of climate change and air pollution on mortality risk for Rome and Milan., 17th Plinius Conference on Mediterranean Risks, Frascati, Rome, Italy, 18–21 Oct 2022, Plinius17-47, https://doi.org/10.5194/egusphere-plinius17-47, 2022.

The Mediterranean Basin, which is considered an hot-spot region in term of air-quality and climate change, frequently experiences surface ozone (O₃) exceedances to European legislated values for human health protection. Indeed, its peculiar meteorological conditions, such as frequent clear sky and high solar radiation in summer, as well as the availability of natural and anthropogenic precursors, enhance the formation of photochemical ozone so increasing the risk of O₃ pollution events in the area.

O₃ is one of the air pollutants of most concern for public health, as it can damage the respiratory and circulatory systems. O₃ can also deteriorate the vegetation, ecosystems, and building materials. Moreover, it is also one of the most important greenhouse gases as a so-called short-lived climate factor. Being a secondary pollutant, the variability of O₃ is strongly dependent on the precursors, the meteorological parameters and the interactions among them through a series of complex and non-linear functions. Such complexity makes the definition of the O₃ control strategies not immediate; this is why the improvement of the extensive networks of continuous O₃ measurements as well as of appropriate methods to analyze O₃ levels and to predict future changes is required.

The abrupt and unplanned anthropogenic emission reductions determined by the COVID-19 lockdown in 2020 produced an extraordinary real-world opportunity to assess the air quality response to changes in emissions. Taking advantage of this circumstance, the present study aims to characterize the influence of both the precursor emissions and the local meteorological conditions during 2020 on the surface ozone concentrations measured in the Basilicata region, (Southern Italy), which is located in the center of the Mediterranean basin.

To these ends, eXtreme Gradient Boosting (XGBoost) machine learning (ML) models were built to provide both the business-as-usual (BAU) and the meteorological normalized O₃ time series. The former allows the estimates of the impact of the lockdown restrictive measures on O₃ by means of the comparison with the observed concentrations, the latter accounts for the meteorological variability and other time features for more reliable assessment of O₃ trend/changes. Moreover, thanks to the non-black box nature of the developed ML models, the partial dependence of the observed O₃ concentrations on each explanatory variables used in the models can be analysed, shedding light on the role of local meteorological processes in the observed O₃ variability.

The results obtained made it possible to evaluate the different contribution of emissions and meteorology on the detected changes in the levels of O₃ and to provide deeper insights of major drivers of surface ozone concentrations in the studied area. This knowledge could help in defining strategies effective in reducing the negative impacts associated with O₃ exposure as well as in optimizing the potential synergies between O₃ reduction policies and climate change policies.

How to cite: Gagliardi, R. V. and Andenna, C.: Evaluation of the effects of the COVID-19 lockdown and the meteorology on surface ozone variability with machine learning techniques. , 17th Plinius Conference on Mediterranean Risks, Frascati, Rome, Italy, 18–21 Oct 2022, Plinius17-16, https://doi.org/10.5194/egusphere-plinius17-16, 2022.

The climate change induced-events are affecting the Mediterranean Sea through ever-increasing frequent and severe heatwaves and droughts, which are primary drivers for wildfires diffusion. This study aims to comprehensively investigate the wildfires' impact on emissions of PM2.5 and Black Carbon during fire seasons in southern Italy.  As a first step, the Lagrangian transport of emissions produced by wildfires and impacting two National Parks of the Calabria region, placed in the middle of the Mediterranean Sea, was estimated for a particularly severe fire season. PM2.5 and Black Carbon observations were taken from the Sila National Park at the Monte Curcio Global Atmosphere Watch (GAW) regional station and the Aspromonte National Park at the Mammola rural-regional background station. These observations were integrated with remote-sensing fire detections and the high-resolution WRF-HYSPLIT back-trajectories, which improved the model accuracy in the orographically complex region of Calabria. Moreover, we evaluated the wildfire impact on human health in terms of passively smoked cigarettes (PSC), related to PM2.5 and Black carbon measurements. Finally, we estimated the PM2.5 and Black Carbon emissions released during the whole analyzed fire season and assessed the uncertainties of remote sensing-based inventories by comparing the temporal and spatial behavior of the last version of the satellite-based Global Fire Emissions Database (GFED4s) with the more accurate ground-based wildfire emissions inventory produced by ISPRA (Institute for Environmental Protection and Research).

How to cite: Castagna, J., Senatore, A., Bencardino, M., Pellis, G., Vitullo, M., and Mendicino, G.: Impact of wildfire emissions of PM2.5 and Black Carbon in southern Italy, 17th Plinius Conference on Mediterranean Risks, Frascati, Rome, Italy, 18–21 Oct 2022, Plinius17-82, https://doi.org/10.5194/egusphere-plinius17-82, 2022.