Two measurement campaigns were conducted at Thessaloniki, an urban station, (40.5°N, 22.9°E; 60 m) in the frame of the PANhellenic infrastructure for Atmospheric Composition and climatEchAnge (PANACEA) project. The first one covers the period from July to August 2019 and the second one from January to February An overview of the aerosol optical properties (columnar and height resolved), acquired with the remote sensing infrastructure of the Laboratory of Atmospheric Physics (LAP) of the Aristotle University of Thessaloniki (AUTH), as well as the additional instrumentation that participated during the PANACEA campaigns is presented. The majority of the detected layers (16 out of 40, ranged between 0.8 and 4.5 km) are classified as biomass burning aerosols, attributed to either city sources or long range transport. Concerning the other aerosol types, the Clean Continental cluster has an occurrence ratio of 23%, while dust layers and mixtures with urban particles transported to Thessaloniki are also identified. Our findings are discussed along with the surface information, i.e., the particulate matter (PM2.5 and PM10) concentrations and the black carbon (BC) concentration, separated into fossil fuel (BC_ff) and biomass/wood burning (BC_wb) fractions. This is the first time that collocated in situ and remote sensing instruments are deployed in Thessaloniki in order to assess the presence of aerosols and the predominant aerosol type both in situ and at elevated heights. Overall, our study showed that the BC_wb contribution to the BC values in Thessaloniki is quite low (11%), whilst the majority of the biomass burning layers identified with the lidar system, are also linked with enhanced BC contribution and high Fine Mode Fraction values.

This study investigates the variability of major air pollutants, such as nitrogen oxides (NO_x, including nitric oxide (NO) and nitrogen dioxide (NO₂)), ozone (O₃), and particulate matter with a diameter ≤ 10 µm (PM10), in Thessaloniki over the period 2001–2022, highlighting their evolution in response to vehicle technology adoption and the COVID-19 pandemic. Four monitoring stations representing urban traffic, urban background, urban industrial, and suburban industrial environments were analyzed. PM10 concentrations generally decreased until 2015 but rose thereafter, mainly due to increased petrol car usage, with the highest levels recorded at the urban traffic station during colder months, influenced by domestic heating and local wind patterns. NO and NO₂ concentrations peaked at urban traffic and industrial sites, closely linked to vehicle emissions and industrial activities, respectively, with notable reductions during the 2020 COVID-19 lockdown. O₃ levels showed steady trends with diurnal and seasonal variability inversely related to NO_x concentrations and positively correlated with temperature. Despite some pollutant reductions, air quality issues persist in Thessaloniki. The findings emphasize the need for robust governmental policies promoting cleaner heating alternatives; two policy scenarios are presented in this respect with the corresponding air pollutant concentrations estimates up to 2035.

This study investigates the projections of solar erythemal dose on global scale, from the middle of the 20^th century until the end of the 21^st century. Calculations of spectral UV radiation were performed with the radiative transfer model libRadtran, using as input data from Earth System Model (ESM) simulations available from the 6^th Phase of the Coupled Model Intercomparison Project (CMIP6). For the projections of UV radiation, three different scenarios were taken into consideration, using different Shared Socioeconomic Pathways (SSPs) of the Intergovernmental Panel on Climate Change (IPCC). In order to gain a global overview of the projections, the UV calculations were performed in five latitude bands with a view to calculate biological doses for erythema, DNA and plant damage. Our calculations for the last years of the 21^st century (2090-2100), as compared to the years 1950-1960, reveal lower biological doses for the three action spectra in most regions assuming the pathways SSP3-7.0 and SSP5-8.5.