A study of indoor environmental quality inside the old (naturally ventilated) and new (air-conditioned) train cabins and platforms of four main stations of the Athens subway system (Attiko Metro), took place in different two-day measurements from June to August 2012. Portable instrumentation provided continuous measurements of particulate matter (PM₁₀, PM_2.5 and PM₁), carbon dioxide (CO₂) along with temperature (T) and absolute humidity (AH). PM concentrations were significantly higher on the underground platforms of the network from 3 to 10 times, as compared to outdoor measurements. In particular, mean PM₁, PM_2.5 and PM₁₀ concentrations at the deeper and most crowded station of Syntagma reached 18.7, 88.1 and 320.8 μg m⁻³ respectively. On the contrary, the ground level, open station of the Airport, showed values comparable to the outdoor (2, 6.4 and 34.4 μg m⁻³, respectively). All PM fractions were lower than the platforms inside the old and new train cabins while the air conditioned trains experienced lower particulate pollution levels. More specifically, mean PM₁, PM_2.5 and PM₁₀ concentrations were 5.5, 16.8 and 58.3 μg m⁻³, respectively in new cabins while in the old they reached 10.3, 47.5 and 238.8 μg m⁻³. The PM_2.5/PM₁₀ and PM₁/PM_2.5 ratios did not exceed 0.33 on both platforms and trains verifying the dominance of crustal coarse particles originating from the train and ground materials. As expected CO₂ levels were higher inside the trains as compared to the platforms and in some cases surpassed the 1000 ppm limit during the hottest days of the experimental campaign. Temperature and humidity remained relatively stable on the platforms, whereas measurements inside the cabins fluctuated, depending on the type of train and track locations. Correlations between measured PM along the routes to and from the Airport indicated covariance of concentrations along train cabins of the same direction.

This paper presents experimental results from a typical school building in Athens, equipped partly with a green roof system (GRS). Environmental monitoring took place in six classrooms located both under the concrete roof and the GRS sectors as well as in the immediate external environment during the warm and cold periods of a school year. Daily measurements of pollutants CO₂, TVOCs (Total Volatile Organic Compound), PM₁, PM_2.5, and PM₁₀ were performed in selected classes. Moreover, indoor ambient temperature (T) and relative humidity (RH) measurements were implemented in order to estimate the absolute humidity (AH) and assess the indoor environmental conditions. The results highlight that during summer, the GRS reduces temperature in a classroom on the top floor by about 2.8 °C, in comparison with the respective classroom under the concrete roof and that AH remained relatively stable for both classrooms. Amid winter, a reverse behavior occurs only for temperature. Moreover, air exchange rates (AER) were calculated by using the CO₂ decay method for all of the classrooms. The results demonstrated insufficient ventilation for all experimental sights. Finally, concentrations of PM₁, PM_2.5 and PM₁₀, were found to be relatively decreased, with average values of 0.79, 3.39, and 27.80 μg m⁻³. Levels of CO₂ and TVOCs were elevated during class hours ranging from 469 to 779 ppm and from 6.63 ppm to 13.33 ppm, respectively, but generally within the respective limits of exposure. The examination of the indoor/outdoor (I/O) ratio of air pollutants, demonstrated that the outdoor meteorology affects only PM₁ and PM_2.5, as PM₁₀ and TVOCs are strongly affected by internal sources and the activities of pupils.

Fine particulate matter (PM) has significant impacts on public health. Among its various chemical components, Polycyclic Aromatic Hydrocarbons (PAHs) are of particular importance since they contribute to a large extent or even enhance its toxic potency. Despite the verified importance of the fine PM pollution for the Greater Athens Area (GAA), information on its composition with respect to the hydrocarbons is extremely scarce. This study aims to uncover the occurrence of the PM_2.5 and PM₁-bound PAHs across the GAA investigating the impact of the sources and meteorology on the configuration of their profile and potential health risk. The fieldwork took place at three different locations during two different mesoscale wind regimes. Using the Diagnostic PAHs’ Ratio method, the sources were identified while for the quantification of the emissions from the traffic and central heating sectors, the FEI-GREGAA emission inventory was taken into consideration. The potential health risk was estimated calculating the toxic/mutagenic equivalency factors. The peaks for both the PM mass and the PAHs were attributed to the intensity of the emissions. On the other hand, the carcinogenic/mutagenic risk was mainly influenced by the varying characteristics of traffic and especially for the background atmosphere, from the arriving air masses from longer scale distances.

Research on air quality issues in recently refurbished educational buildings is relatively limited. However, it is an important topic as students are often exposed to high concentrations of air pollutants, especially in urban environments. This study presents the results of a 25-day experimental campaign that took place in a primary school located in a densely built-up area, which retains a green roof system (GRS). All measurements refer to mass concentrations and chemical analysis of PM₁₀ (particulate matter less than 10 micrometers), and they were implemented simultaneously on the GRS and within the classroom (C3) below during different periods of the year. The results demonstrated relatively low levels of PM₁₀ in both experimental points, with the highest mean value of 72.02 μg m⁻³ observed outdoors during the cold period. Elemental carbon (EC) was also found be higher in the ambient environment (with a mean value of 2.78 μg m⁻³), while organic carbon (OC) was relatively balanced between the two monitoring sites. Moreover, sulfate was found to be the most abundant water soluble anion (2.57 μg m⁻³), mainly originating from ambient primary SO₂ and penetrating into the classroom from windows. Additionally, the crustal origin of particles was shown in trace metals, where Al and Fe prevailed (9.55% and 8.68%, respectively, of the total PM₁₀). Nevertheless, infiltration of outdoor particles within the classroom was found to affect indoor sources of metals. Finally, source apportionment using a positive matrix factorization (PMF) receptor model demonstrated six main factors of emissions, the most important of which were vehicles and biomass burning (30.30% contribution), along with resuspension of PM₁₀ within the classroom from human activities (29.89% contribution). Seasonal variations seem to play a key role in the results.

The pollutants emitted during meal preparation in restaurants deteriorate the air quality. Thus, it is an environmental issue that needs to be addressed, especially in areas where these activities are densely located. The purpose of this study is to examine the impact on air quality from commercial cooking activities by performing a qualitative and quantitative analysis of the related parameters. The area of interest is located in the southeastern Mediterranean (Greater Athens area in Greece). Due to the lack of the necessary activity information, a survey was conducted. Emissions from the fuel burnt during the cooking procedures were calculated and it was found that, overall, 940.1 tonnes are attributed to commercial cooking activities annually (generated by classical pollutants, heavy metals, particulates and polycyclic aromatic hydrocarbon emissions). Comparing the contribution of different sources to the pollutants emitted, it was found that commercial cooking is responsible for about 0.6%, 0.8% and 1.0% of the total CO, NOx and PM10 values. Cooking organic aerosol (COA) and volatile organic compound (VOC) emissions from grilled meat were also calculated, accounting for 724.9 tonnes and 37.1 tonnes, respectively. Monthly, daily and hourly profiles of the cooking activities were developed and emissions were spatially disaggregated, indicating the city center as the area with higher values. Numerical simulations were performed with the WRF/CAMx modeling system and the results revealed a contribution of about 6% to the total PM10 concentrations in the urban center, where the majority of restaurants are located.