Remotely Sensed Data Fusion for Spatiotemporal Geostatistical Analysis of Forest Fire Hazard.

Forest fires are a natural phenomenon which might have severe implications on natural and anthropogenic ecosystems. Future projections predict that, under a climate change environment, the fire season would be lengthier with higher levels of droughts, leading to higher fire severity. The main aim of this paper is to perform a spatiotemporal analysis and explore the variability of fire hazard in a small Greek island, Skiathos (a prototype case of fragile environment) where the land uses mixture is very high. First, a comparative assessment of two robust modeling techniques was examined, namely, the Analytical Hierarchy Process (AHP) knowledge-based and the fuzzy logic AHP to estimate the fire hazard in a timeframe of 20 years (1996-2016). The former technique was proven more representative after the comparative assessment with the real fire perimeters recorded on the island (1984-2016). Next, we explored the spatiotemporal dynamics of fire hazard, highlighting the risk changes in space and time through the individual and collective contribution of the most significant factors (topography, vegetation features, anthropogenic influence). The fire hazard changes were not dramatic, however, some changes have been observed in the southwestern and northern part of the island. The geostatistical analysis revealed a significant clustering process of high-risk values in the southwestern and northern part of the study area, whereas some clusters of low-risk values have been located in the northern territory. The degree of spatial autocorrelation tends to be greater for 1996 rather than for 2016, indicating the potential higher transmission of fires at the most susceptible regions in the past. The knowledge of long-term fire hazard dynamics, based on multiple types of remotely sensed data, may provide the fire and land managers with valuable fire prevention and land use planning tools.

PM2.5 source apportionment for the port city of Thessaloniki, Greece.

This paper aims to identify the chemical fingerprints of potential PM2.5 sources and estimate their contribution to Thessaloniki port-city's air quality. For this scope, Positive Matrix Factorization model was applied on a comprehensive PM2.5 dataset collected over a one-year period, at two sampling sites: the port and the city center. The model indicated six and five (groups of) sources contributing to particle concentration at the two sites, respectively. Traffic and biomass burning (winter months) comprise the major local PM sources for Thessaloniki (their combined contribution can exceed 70%), revealing two of the major control-demanding problems of the city. Shipping and in-port emissions have a non-negligible impact (average contribution to PM2.5: 9-13%) on both primary and secondary particles. Road dust factor presents different profile and contribution at the two sites (19.7% at the port; 7.4% at the city center). The secondary-particle factor represents not only the aerosol transportation over relatively long distances, but also a part of traffic-related pollution (14% at the port; 34% at the city center). The study aims to contribute to the principal role of quantitative information on emission sources (source apportionment) in port-cities for the implementation of the air quality directives and guidelines for public health.

PM1 and PM2.5 ionic composition and VOCs measurements in two typical apartments in Athens, Greece: investigation of smoking contribution to indoor air concentrations.

During the last decades, the air quality of the city of Athens has been quite aggravated. Scientific interest has been focused on health effects caused by both outdoor and indoor air pollution. The purpose of this study was the presentation of results from air quality measurements in two similar typical Athenian apartments in the same suburban area. In addition, smoking contribution is investigated, as it is the main factor which differentiates the two apartments. The results showed that it is the outdoor environment that mainly contributes to the air quality of the non-smokers' house. In the second apartment, PM2.5, PM1, and benzene concentrations were found significantly higher due to smoking activity. In contrast, no clear difference in particulate matter ionic composition between the two areas was observed, although in the smoker's house, ion concentrations were found elevated. This observation amplifies the assumption that in the smoker's apartment, significant outdoor sources' contribution cannot be excluded.

Mortality and pollution in several Greek cities.

This study examined the atmospheric pollution created by industry and traffic areas nearby the city of Kavala and the mortality of citizens in the region. The mortality data spanned over a period of 30 years. The statistical data on mortality was collected from 1968 to 1998. The causes of mortality analyzed in this study were cancer, cardiovascular deaths and pulmonary deaths. The results of this study were compared with other Greek cities. Air measurements were made over a period of 6 months and included levels of gaseous emissions as well as concentrations of Volatile Organic Compounds (VOCs), near the city of Kavala, where reservoirs of petroleum and exploitation of crude oil were present. Samples of air were collected from ambient surroundings near the industrial area and fuel oil facilities. The results obtained from the study indicated the presence of aromatic and aliphatic hydrocarbons and other gaseous pollutants such as, methane, o-, m-, p-xylene and ethylbenzene, etc. In some cases the levels exceeded the concentration limits specified by the air quality standards. Offensive odors were also detected (H2S). The study revealed that adverse environmental impact of air pollutants is a major concern in the industrial centers more than in the rural areas. This poses a threat to the public health and may induce disease and premature deaths. These air pollutants play an important role in air quality.