COVID-19 is evolving into one of the worst pandemics in recent history. The lockdown measures implemented worldwide to slow the spread of the COVID-19 pandemic have caused an unprecedented reduction in global economic activity. Strict lockdown measures came into force in Greece from March 23th 2020. This study aims to assess the changes in air pollution levels during the restriction measures in Athens, the city with the most COVID-19 cases in the whole country. Measurements in a central location during the lockdown (24/03/2020 -07/04/2020) were compared with levels during the pre-lockdown (19/02/2020 -11/03/2020) period. Urban air pollution markedly decreased but with substantial differences among pollutants. The most significant impact during the lockdown period was observed for the concentrations of carbon monoxide (CO) and nitrogen oxides (NOx) with reduction percentages of -47% and - 35%, respectively, compared to the pre-lockdown period. These air pollutants are mainly related to traffic emissions. A lower reduction was recorded for coarse particulate matters (PM10) (-24%), probably due to the existence of other local sources of emission along with secondary formation. Nevertheless, this result must be further examined in order to be interpreted. Additionally, meteorological parameters such as wind speed found to play a key role on the results as most air pollutants were negatively correlated with higher air velocities. The scope of this study is to provide short term air quality results to the existing literature, in order to enhance decision making on life quality improvement in respect to the urban environment.

This study's scope is to collect and analyze all the needed information related to the residential building stocks in Mediterranean countries, especially those that participated in the framework of the HAPPEN project (Greece, Croatia, Cyprus, Italy, Slovenia, Spain, and France). A specific procedure was followed in order to conduct a coordinated evaluation of the residential building stock. The most important variables for a statistical examination of the building stock are outlined, as well as an approach for establishing reference buildings. National data for the seven participating nations were collected and evaluated using the prescribed methodology. The research findings identify six distinct reference buildings in each nation. More specifically, the most representative buildings were distinguished through a cross-country comparison of the obtained data, after classifying the buildings into different classes to which the same approach for deep renovation/refurbishment can be applied.

The coronavirus disease 2019 (COVID-19), which is mainly transmitted through droplets without overlooking other sources of transmission, rendered attention on the air quality in indoor areas and more specifically in healthcare settings. The improvement of indoor air quality (IAQ) is ensured by frequent changes of the air that must be carried out in healthcare areas and with assistance from special devices that undertake the filtration of the air and its purification through special filters and lamps. In this research, the performance of air purifiers is assessed in terms of the limitation of PM2.5, PM10, VOCs and CO2 in a postgraduate clinic of the Dentistry School of the National and Kapodistrian University of Athens in parallel with mechanical ventilation. Our findings indicate that the use of mechanical ventilation plays a key role on the results, retaining good IAQ levels within the clinic and that air purifiers show a positive impact on IAQ by mainly reducing the levels of PM2.5 and secondly of TVOC.

Background: Air pollution is a well-described environmental factor with evidence suggesting a firm association with cardiovascular diseases. The purpose of this study was to determine the association of exposure to gaseous air pollutants on atherosclerosis burden. Methods: 1955 inhabitants of the Corinthia region, aged 40 years or older, underwent clinical and biochemical assessment as well as carotid ultrasonography to evaluate carotid intima-media thickness (cIMT) and plaque burden. Analyzers recording time series concentration of CO, NO2, and SO2 were located at 4 different open sites (Regions 1, 2, 3 and 4) based on their proximity to industries, highways or shipyards. Results: A higher concentration of CO, NO2, and SO2 was observed in Region 4 compared to the other regions. Mean cIMT (Region 1: 0.93 +/- 0.24 mm; Region 2: 0.96 +/- 0.40 mm; Region 3: 0.94 +/- 0.39 mm; Region 4: 1.14 +/- 0.55 mm, p < 0.001), maximum cIMT (p < 0.001) as well as carotid plaque burden (Region 1: 13.3%; Region 2: 18.8%; Region 3: 22.4%; Region 4: 38.6%, p < 0.001) were significantly higher in individuals of Region 4. Inhabitants of Region 4 had also higher levels of C reactive protein (Region 1: 4.56 +/- 4.85 mg/l; Region 2: 3.49 +/- 4.46 mg/l; Region 3: 4.03 +/- 3.32 mg/l, Region 4: 5.16 +/- 8.26 mg/l, p < 0.001). Propensity score analysis revealed higher inter-area differences in mean cIMT of individuals with coronary artery disease (CAD) (high vs low air pollution area: 1.56 +/- 0.80 mm; vs. 1.18 +/- 0.54 mm, p < 0.001) while there was no difference in cIMT of the matched population without CAD (p = 0.52). Conclusions: An increased carotid atherosclerotic and inflammatory burden is observed in inhabitants of areas with the highest concentration of air pollutants.

The assessment of indoor environmental quality in historic buildings converted to museums is a significant tool in deep energy renovation processes, as it provides insights for the microclimatic conditions in the interiors of the building where vast numbers of visitors walk every year and where artifacts that are vulnerable to pollution are exhibited. In this work, aiming to contribute to the development of an energy retrofitting protocol applied in the Mediterranean region (HAPPEN MedZeb protocol) for museums hosted in historic buildings by providing useful data, an experimental campaign to evaluate the indoor environmental quality of a museum housed in a historic building located in Athens took place from February 2019 to April 2021 and was divided into two periods. The findings revealed high concentrations of volatile organic compounds as well as poor thermal comfort levels since the sensors recorded low acceptable percentages of T values within the limits from 7 to 33% for the entire experimental period. Based on the findings, recommendations for retrofitting interventions are made.

Urbanization and climate change are two major issues that humanity faces in the 21st century. Megacities are large urban agglomerations with more than 10 million inhabitants that emerged in the 20th century. The world’s top 100 economies include many North and South American megacities, such as New York, Los Angeles, Mexico City, Sao Paulo and Buenos Aires; European cities such as London and Paris; and Asian cities such as Tokyo, Osaka, Seoul, Beijing and Mumbai. This paper addresses a dearth of megacity energy metabolism models in the literature. Cross-sectional data for 36 global megacities were collected from many literature and Internet sources. Variables included megacity name, country and region; population; area; population density; (per capita) GDP; income inequality measures; (per capita) energy consumption; household electricity prices; (per capita) carbon and ecological footprint; degree days; average urban heat island intensity; and temperature and precipitation. A descriptive comparison of the characteristics of megacities was followed by ordinary least squares with heteroskedasticity-robust standard errors that were used to estimate four alternative multiple regression models. The per-capita carbon footprint of megacities was positively associated with the megacity GDP per capita, and the megacity ecological footprint; and negatively associated with country income inequality, a low-income country dummy, the country household electricity price, and the megacity annual precipitation. Targeted policies are needed, but more policy autonomy should be left to megacities. Collecting longitudinal data for megacities is very challenging but should be a next step to overcome misspecification and bias issues that plague cross-sectional approaches.