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1 Introduction

The difficult economic effects on urban economy in the last six years in Greece lead the majority of people turn to alternative forms for domestic heating such as the uncontrolled consumption of biomass, i.e. firewood and any other form of artificial substitutes (Kollias et al. 2014). The particles released from burning wood contain organic toxic ingredients such methylphenol (Kjällstrand and Petersson 2001) and polycyclic aromatic hydrocarbons (Barregard et al. 2006). Numerous studies have certified that biomass burning contributes as a release source of fine particles PM2.5 (e.g. Zheng et al. 2005; Verma et al. 2009, Daher et al. 2012; Saffari et al. 2013).

Exposure to emissions from biomass combustion leads to particular adverse health effects such as cardiorespiratory problems, increased blood pressure, increased mortality/decrease of life expectancy, lung disorders and lung cancer, systemic inflammation and oxidative stress (Barregard et al. 2006; Orozco -Levi et al. 2006; McCracken et al. 2007; Mousiopoulos 2013; Saffari et al. 2013).

One of the biggest problems of air pollution in the city of Thessaloniki is the high concentrations of suspended particles. Airborne particles vary in terms of their concentration, and physical, chemical and morphological characteristics (Samara et al. 2011). Emitted primary (anthropogenic processes, soil erosion, sea droplets) and suspended directly in the atmosphere in particulate form, either produced secondarily in the atmosphere (condensation, nucleation, chemical conversion). Suspended particles with equivalent aerodynamic diameter less than 10 μm (PM10, respirable suspended particulates) can act as carriers for various chemical compounds for biological contaminants adsorbed or adhered on them, as well as catalysts of chemical reactions that occur in the atmosphere, which mainly contribute to air pollution. These particles are separated into particles having diameter less than 2.5 μm (fine particles) and greater than 2.5 μm (coarse particles). Airborne particles of diameter less than 2.5 μm are able to enter the respiratory system and then via the lungs into the bloodstream.

High concentrations of suspended particles at ground level occur during smog conditions, in association with high levels of sulfur dioxide, or with photochemical pollutants such as O3, NO2, PAN, etc. The most intense incidents of smog formation occur in urban areas, where light winds and a shallow boundary layer air act combined resulting to concentration of pollutants in a relatively small volume of air. The weather-meteorological conditions enhance the formation of this kind of cloud that usually occurs during the winter period in early morning hours (Kourtidis et al. 2002; Marley and Frederick 2008).

The present study examines the impact of air pollutants in the atmosphere of Thessaloniki during years 2012-13. Mineralogical and organic material analysis was implemented on falling dust collected at building rooftop level from three sampling location areas that are Kalamaria (East Thessaloniki), Aristotle University (center of Thessaloniki) and Seaport (West Thessaloniki).

2 Methodology

2.1 Sampling and Sample Preparation

Falling-dust samples collected at rooftop building level from three selected sampling sites in Kalamaria district (multi-storey building), Aristotle University (building roof of the Faculty of Sciences) and Seaport (multi-storey parking lot station). Sampling was carried out during the period June 2012–May 2013 between 23:00 to 00:00, twice a month every 15 days. From each sample 50–150 g of powder was collected, wiping an area of 1 m2 using sterilized collectible instruments. The samples were dried in an oven at 35 °C for 3 days. After that the < 63 μm fraction was separated by sieving for further investigation. A total number of over 70 samples (3 sampling locations × 2 samples per month × 12 months = 72 samples) were collected between June 2012 and May 2013.

2.2 Analytical Methods

The mineralogical composition of the studied samples was determined by X-ray Powder Diffraction (XRPD) method. The XRPD analysis was performed using a Philips PW1710 diffractometer with Ni-filtered CuKα radiation on randomly oriented samples. The counting statistics of the XRPD study were: step size: 0.01° 2θ, start angle: 3°, end angle: 63° and scan speed: 0.02° 2θ/s. Quantitative estimates of the abundance of the mineral phases derived from the XRPD data, using the intensity of a certain reflections and external standard mixtures of minerals (Kantiranis et al. 2004). The proportion of amorphous material (organic and inorganic origin) was calculated according to the methodology described by Kantiranis et al. (2004).

The calculation of the contained organic material was determined in each according to Jackson (1974) with the effect of an aqueous solution 30 % H2O2 in a representative sample of the <63 μm fraction.

3 Results and Discussion

3.1 Mineralogical Analysis and Organic Material

In Table 1 the mean value, standard variation, minimum and maximum amounts of the minerals and the amorphous content determined in the <63 μm sample fraction are shown. Also, the weight and the organic material of the <63 μm fraction are given. More specifically, the <63 μm fraction of the total amount of falling dust during 2012–13 ranged from 10.3 % (Autumn 2012) to 27.5 % (Spring 2013). It is clear from Fig. 1 that the mean weight of the <63 μm fraction is progressively increasing from Summer 2012 to Spring 2013. Kollias et al. (2014), comparing the periods of December 2011 and December 2012, found an incensement in the amount of <63 μm fraction of falling dust during December 2012 in the same sampling sites and attributed this observation to favorable meteorological conditions with atmospheric stability and low winds.

Fig. 1
figure 1

Annual variation (wt. %) of the weight and the amounts of calcite, quartz, feldspars, amorphous and organic material of the <63 μm fraction of the studied samples

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Table 1 Weight (%) of the <63 μm fraction, semi-quantitative mineralogical composition (wt%) and organic matter (wt%) of the studied samples
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According to the results of the mineralogical analysis (Table 1), the samples of falling dust primarily consist of calcite (35–45 wt%) and quartz (29–35 wt%) as major phases, feldspars and dolomite in lesser percentages, while mica, clay minerals and amphibole were detected in very small quantities. Gypsum was measured at low amounts in Spring 2013. Furthermore, significant amounts of amorphous phases were identified (7–15 wt%).

Quartz (SiO2) is one of the most resistant mineral to the physical and chemical erosion. The possible effects of the crystalline forms of silica (most common quartz) on health are of particular interest (Ikeda et al. 1986), while the International Agency for Research on Cancer (1997) classifies them as carcinogenic to humans (Category I). Also, calcite, dolomite, feldspars and gypsum derived probably from the erosion of building materials (Tossavainen and Forrssberg 1999).

The phyllosilicate minerals (mica and clay minerals) may possibly be derived from the corrosion of construction materials and deposited directly on the ground, but it is probably due to their lamellar structure and low specific weight can be carried out by re-suspending from other regions. The amorphous phases derive from the incomplete combustion of organic material (mainly solid and liquid fuels) and from the corrosion of inorganic aluminosilicate phases of buildings components.

The organic material was measured at concentrations between 3 wt% (Summer 2012 and Spring 2013) and 10 wt% (Winter 2012–13) showing significant differences between seasons. Specifically, in the samples collected during Winter higher participation of organic material was found. During Winter 2012-13, the mean amount of organic matter is more than 3 times higher compared with Summer 2012 and Spring 2013 and more than 1.5 times higher compared with Autumn 2012. Kollias et al. (2014) found higher amounts of organic material comparing December 2012 with December 2011 and September 2012 and conclude that this can be attributed to the extensive and uncontrolled burning of biomass for domestic heating. Petrakakis et al. (2013) found increased concentrations of particulate matter in Thessaloniki during the Winter period after 2010 which attributed to the burning of wood and other types of biomass. According to Moussiopoulos (2013) the burning of biomass and wood led to a rapid increase in the average monthly concentration of fine particles in the Winter period (Nov 2012–January 2013), with this increase being more pronounced in afternoon hours. Moreover, Saffari et al. (2013) found that in the urban background of Thessaloniki’s region concentrations of PM2.5 in the Winter of 2013 were 30 % higher compared to the same period in 2012 and 2–5 times higher concentrations of the biomass combustion indicators such as water-soluble K, anhydrides sugars, organic carbon and PAHs.

4 Conclusions

Mineralogical analysis and organic material of the falling dust samples collected from rooftops in three sampling sites during Summer 2012-Spring 2013 from three sampling sites in the wider conurbation of Thessaloniki found that:

  • The fallen dust mainly consists of inorganic origin components from the corrosion of building materials without excluding material contribution from air suspending fumes.

  • Calcite and quartz are the major inorganic crystalline phase determined with the latter to be potentially dangerous for public health.

  • A significant increase in the organic load of dust samples had been observed for Winter 2012–13 compared to the other seasonal sampling periods and to previous Winter and Autumn monthly periods

  • The pollution impact of the atmosphere of Thessaloniki with pollutants of organic origin during the Winter 2012–13 attributed to the extensive and uncontrolled burning of biomass for domestic heating. This is a consequence of the economic crisis in Greece and the high value of petroleum fuel during this period.