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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. © 2020 by the authors. Licensee MDPI, Basel, Switzerland.

Substantial knowledge is available on the association of the indoor school environment and its effect among schoolchildren. In the same context, the SINPHONIE (School indoor pollution and health: Observatory network in Europe) conducted a study to collect data and determine the distribution of several indoor air pollutants (IAPs), physical and thermal parameters and their association with eye, skin, upper-, lower respiratory and systemic disorder symptoms during the previous three months. Finally, data from 115 schools in 54 European cities from 23 countries was collected and included 5175 schoolchildren using a harmonized and standardized protocol. The association between exposures and the health outcomes were examined using logistic regression models on individual indoor air pollutants (IAPs); a VOC (volatile organic compound) score defined as the sum of the number of pollutants to which the children were highly exposed (concentration > median of the distribution) in classroom was also introduced to evaluate the multiexposure – outcome association, while adjusting for several confounding factors. Schoolchildren exposed to above or equal median concentration of PM2.5, benzene, limonene, ozone and radon were at significantly higher odds of suffering from upper, lower airways, eye and systemic disorders. Increased odds were also observed for any symptom (sick school syndrome) among schoolchildren exposed to concentrations of limonene and ozone above median values. Furthermore, the risks for upper and lower airways and systemic disorders significantly increased with the VOCs score. Results also showed that increased ventilation rate was significantly associated with decreased odds of suffering from eye, skin disorders whereas similar association was observed between temperature and upper airways symptoms. The present study provides evidence that exposure to IAPs in schools is associated with allergic and respiratory symptoms in children. Further investigations are needed to confirm our findings. © 2020 Elsevier B.V.

Τhe extreme weather conditions in Middle East Area led to the construction of tightly sealed, air conditioned buildings, characterized by indoor air quality deterioration. This study presents the results of chemical characterization of outdoor and indoor PM2.5 and PM10 in Doha city, over a two-month period including normal days and dust events, aiming at identifying the factors affecting the indoor air of an office building. The WHO guideline values were exceeded in 100% of the outdoor measurements. 49% of the days of the sampling campaign were characterized as non-dusty (PM10 < 200 µg m–3), 49% as minor-dusty (200 < PM10 < 1000 µg m–3) while in one case (2%) there was a major-dusty day (PM10 > 1000 µg m–3). The contribution of both dust and anthropogenic emissions sources is depicted in particles’ mass and chemical composition. The elevated –especially outdoor- levels of carbonate carbon indicate the presence of crustal matter originating from the surrounding crustal material. OC/EC values reveal possible combined contribution from secondary organic aerosol, trafficrelated sources and re-suspended dust. The influence of anthropogenic emissions is implied by the predominance of nitrate and sulfate ions, which constitute a substantial percentage of the particle mass. The crustal origin of particles is also depicted in metals. However, the higher enrichment factor values which may imply anthropogenic activities of both the outdoor and indoor environment were determined sequentially for Cd, Pb, As, Cu and Zn, suggesting the role of infiltration. Concluding, the indoor to outdoor relationship is significantly influenced by particles infiltration and penetration into the building mainly through the ventilation system and to a lesser extent, through windows or cracks in the building envelope. Although the low indoor to outdoor ratio underlies the predominance of outdoor levels compared to the indoor ones, there is positive correlation between indoor and outdoor PM, during the days that the building was open to the public and employees. © Taiwan Association for Aerosol Research.

The aim of the present study was to identify the main sources contributing to the air pollution of three indoor environments of different use: a museum, a printery industry and an office. For that purpose, particulate matter (TSP, PM10, PM2.5), inorganic pollutants (NOx, SO2, O3) and organic compounds (BTX, formaldehyde) were monitored. Factors such as the kind of the activities occurred indoors, the emissions from the existing equipment, the number of occupants, the ventilation pattern and the outdoor background substantially varied among the three sites. The average values of PM2.5 (151 μg m-3), benzene (69.4 μg m-3), toluene (147 μg m-3), SO2 (47 μg m-3) and NO2 (96.6 μg m-3) were the highest values recorded during the experimental campaigns while all of them measured in the printery industry. Formaldehyde presented the highest concentration value in the museum (50.5 μg m-3). O3 was measured to have the highest concentration in the non smokers' office (238 μg m-3) while the lowest was found in the presser section of the printer industry (11.0 μg m-3). The location of the sites seems to play a significant role, too. Benzene/toluene ratio indicated traffic as a major source. Furthermore, ozone presented low levels in the printery and the museum (urban area) and relatively higher levels in offices (suburban area), indicating its outdoor origin. © 2011 Elsevier Ltd.

The purpose of the present work was to study experimentally the indoor air quality status regarding PM10, PM2.5, TVOCs, CO2, NOx, SO2 and O3 in selected differently used areas. A flat on the third floor of a multi-storey building, located at a suburban area north-east of the centre of Athens and close to a heavily trafficked road and two offices of the Environmental Physics Department building at the University campus, in a suburban area were selected for the purpose of the measurements. The experimental campaigns covered several days in each area in order to include different indoor conditions and outdoor concentration levels. Total VOCs and CO2 were measured on a continuous basis at selected locations only in the indoor environment with two sets of portable samplers. Indoor and outdoor NOx, SO2 and O3 were measured with analysers. PM10 and PM2.5 24 hour averaged measurements were taken with the aid of two sets of indoor particle samplers. Experimental results obtained from Offices 1 and 2 indicate that the indoor air quality in both offices is satisfactory with respect to NOx, SO2 and O3. PM10 concentrations are well above the specified limits on days of smoking or closure of windows in both offices. The indoor air quality in Office 1 seems satisfactory with respect to CO2 and total VOCs concentrations measured, even on days when smoking was taking place and windows were kept closed while all occupants were present. In Office 2, both CO2 and total VOCs concentrations are elevated, even on days when the windows were open or smoking was not taking place, but do not exceed the specified limits, indicating poor air renewal. Experimental data obtained from the residence indicate firstly that NOx, SO2 and O3 concentrations in the indoor environment depend directly on the outdoor levels as they presented the same diurnal variation, while the indoor values were lower than the outdoor ones. Surprisingly enough, the total VOCs concentrations in the living room presented high values when windows were kept open indicating strong presence of outdoor sources. Furthermore, activities such as cooking, cleaning, smoking and use of indoor air fresheners further increased the total VOCs levels. Regarding CO2 concentrations, they were almost constant indicating acceptable but not satisfactory renewal of the indoor air. Finally, PM10 concentration measurements were most of the time below the specified limits, with some exceptions mainly related to window opening and cooking. © 2008 Global NEST Printed in Greece. All rights reserved.

Twenty-three hours samples of airborne aerosols PM2.5 were collected during summer (August-September) and winter (October-November) 2003 in a suburban area of Athens (Aghia Paraskevi), Greece. The objective of this study is the determination of heavy metals (Hg, Cd, Ni, Pb, As) concentration in PM2.5. In particular, the mean daily concentrations of the five detected metals are compared to the limit values established by the E.U (Directive 96/62/E.U.) and correlated with the mean daily concentrations of PM2.5 as well as with meteorological parameters. Finally, the present work examines the daily levels of fine particles in comparison with the proposed limit values from the U.S. Environmental Pollution Agency (65 μg/m3) and investigates their interaction with other inorganic air pollutants. The concentrations of PM2.5 as well as the concentrations of the five heavy metals proved to be lower than the limit values. Additionally fine particles proved to be strongly influenced by the photochemical processes that take place during the hot days of the year. As far as the heavy metals are concerned, only Cd and Pb seem to be slightly correlated. © 2006 Springer Science+Business Media, B.V.

Twenty-three hour measurements of PM2.5 particulate matter have been carried out during the period between the 1st April and the 13th November 2003 in a suburban area of Athens. The monitoring site was located in the National Research Center "DEMOKRITOS", on the foot of Hemittos Mountain and about 12 km away from the center of Athens. The site covers an area of 600 acres in a forest of pine trees close enough to the newly constructed Hemittos Mountain peripheral highway. PM2.5 samples were collected on 47 mm filters, with the use of low volume gravimetric samplers while a meteorological station recorded meteorological data 6 m above the ground, nearby the sampling instrumentation. The daily average PM2.5 concentration reached 21.1 μg m-3 and all measurements were below U.S. Environmental Pollution Agency daily limit (65 μg m-3). A regression analysis was used to investigate the relationship among PM 2.5 concentrations and meteorological parameters. Additionally, PM2.5 mass concentrations were correlated with other inorganic gaseous pollutants (O3, NO, NO2, SO2) while weekly and seasonal PM2.5 variations were also investigated. © 2005 Elsevier B.V. All rights reserved.

The performance and the uncertainty of receptor models (RMs) were assessed in intercomparison exercises employing real-world and synthetic input datasets. To that end, the results obtained by different practitioners using ten different RMs were compared with a reference. In order to explain the differences in the performances and uncertainties of the different approaches, the apportioned mass, the number of sources, the chemical profiles, the contribution-to-species and the time trends of the sources were all evaluated using the methodology described in Bells et al. (2015). In this study, 87% of the 344 source contribution estimates (SCEs) reported by participants in 47 different source apportionment model results met the 50% standard uncertainty quality objective established for the performance test. In addition, 68% of the SCE uncertainties reported in the results were coherent with the analytical uncertainties in the input data. The most used models, EPA-PMF v.3, PMF2 and EPA-CMB 8.2, presented quite satisfactory performances in the estimation of SCEs while unconstrained models, that do not account for the uncertainty in the input data (e.g. APCS and FA-MLRA), showed below average performance. Sources with well-defined chemical profiles and seasonal time trends, that make appreciable contributions (>10%), were those better quantified by the models while those with contributions to the PM mass close to 1% represented a challenge. The results of the assessment indicate that RMs are capable of estimating the contribution of the major pollution source categories over a given time window with a level of accuracy that is in line with the needs of air quality management. (C) 2015 The Authors. Published by Elsevier Ltd.