Local and regional air pollution characteristics in Cyprus: A long-term trace gases observations analysis.

Observations of key gaseous trace pollutants, namely NO, NOy, CO, SO2 and O3, performed at several curb, residential, industrial, background and free-troposphere sites were analyzed to assess the temporal and spatial variability of pollution in Cyprus. Notably, the analysis utilized one of the longest datasets of 17 years of measurements (2003-2019) in the East Mediterranean and the Middle East (EMME). This region is considered a regional hotspot of ozone and aerosol pollution. A trend analysis revealed that at several stations, a statistically significant decrease in primary pollutant concentration is recorded, most likely due to pollution control strategies. In contrast, at four stations, a statistically significant increase in ozone levels, ranging between 0.36 ppbv y-1 and 0.82 ppbv y-1, has been observed, attributed to the above strategies targeting the reduction of nitrogen oxides (NOx) but not that of Volatile Organic Compounds (VOCs). The NO and NOy, and CO levels at the Agia Marina regional background station were two orders of magnitude and four times lower, respectively, than the ones of the urban centers. The latter denotes that local emissions are not negligible and control a large fraction of the observed interannual and diurnal variability. Speciation analysis showed that traffic and other local emissions are the sources of urban NO and NOy. At the same time, 46 % of SO2 and 40 % of CO, on average, originate from long-range regional transport. Lastly, a one-year analysis of tropospheric NO2 vertical columns from the TROPOMI satellite instrument revealed a west-east low-to-high gradient over the island, with all major hotspots, including cities and powerplants, being visible from space. With the help of an unsupervised machine learning approach, it was found that these specific hotspots contribute overall around 10 % to the total NO2 tropospheric columns.

Involvement of oxidative stress and calcium signaling in airborne particulate matter - induced damages in human pulmonary artery endothelial cells.

Recent studies have revealed that particulate matter (PM) exert deleterious effects on vascular function. Pulmonary artery endothelial cells (HPAEC), which are involved in the vasomotricity regulation, can be a direct target of inhaled particles. Modifications in calcium homeostasis and oxidative stress are critical events involved in the physiopathology of vascular diseases. The objectives of this study were to assess the effects of PM2.5 on oxidative stress and calcium signaling in HPAEC. Different endpoints were studied, (i) intrinsic and intracellular production of reactive oxygen species (ROS) by the H2DCF-DA probe, (ii) intrinsic, intracellular and mitochondrial production of superoxide anion (O2-) by electronic paramagnetic resonance spectroscopy and MitoSOX probe, (iii) reactive nitrosative species (RNS) production by Griess reaction, and (vi) calcium signaling by the Fluo-4 probe. In acellular conditions, PM2.5 leads to an intrinsic free radical production (ROS, O2-) and a 4h-exposure to PM2.5 (5-15µg/cm2), induced, in HPAEC, an increase of RNS, of global ROS and of cytoplasmic and mitochondrial O2- levels. The basal intracellular calcium ion level [Ca2+]i was also increased after 4h-exposure to PM2.5 and a pre-treatment with superoxide dismutase and catalase significantly reduced this response. This study provides evidence that the alteration of intracellular calcium homeostasis induced by PM2.5 is closely correlated to an increase of oxidative stress.

Airborne mineral components and trace metals in Paris region: spatial and temporal variability.

A variety of mineral components (Al, Fe) and trace metals (V, Cr, Mn, Ni, Cu, Zn, Cd, Pb) were simultaneously measured in PM2.5 and PM10 fractions at three different locations (traffic, urban, and suburban) in the Greater Paris Area (GPA) on a daily basis throughout a year. Mineral species and trace metal levels measured in both fractions are in agreement with those reported in the literature and below the thresholds defined by the European guidelines for toxic metals (Cd, Ni, Pb). Size distribution between PM2.5 and PM10 fractions revealed that mineral components prevail in the coarse mode, while trace metals are mainly confined in the fine one. Enrichment factor analysis, statistical analysis, and seasonal variability suggest that elements such as Mn, Cr, Zn, Fe, and Cu are attributed to traffic, V and Ni to oil combustion while Cd and Pb to industrial activities with regional origin. Meteorological parameters such as rain, boundary layer height (BLH), and air mass origin were found to significantly influence element concentrations. Periods with high frequency of northern and eastern air masses (from high populated and industrialized areas) are characterized by high metal concentrations. Finally, inner city and traffic emissions were also evaluated in PM2.5 fraction. Significant contributions (>50 %) were measured in the traffic site for Mn, Fe, Cr, Zn, and Cu, confirming that vehicle emissions contribute significantly to their levels, while in the urban site, the lower contributions (18 to 33 %) for all measured metals highlight the influence of regional sources on their levels.

Global air pollution crossroads over the Mediterranean.

The Mediterranean Intensive Oxidant Study, performed in the summer of 2001, uncovered air pollution layers from the surface to an altitude of 15 kilometers. In the boundary layer, air pollution standards are exceeded throughout the region, caused by West and East European pollution from the north. Aerosol particles also reduce solar radiation penetration to the surface, which can suppress precipitation. In the middle troposphere, Asian and to a lesser extent North American pollution is transported from the west. Additional Asian pollution from the east, transported from the monsoon in the upper troposphere, crosses the Mediterranean tropopause, which pollutes the lower stratosphere at middle latitudes.