Workplace personal exposure to respirable PM fraction: a study in sixteen indoor environments

AbstractThe present paper focuses on respirable particulate matter (RPM) measurements conducted at the breathing zone of adult volunteers in sixteen different working environments: two offices, a house, a chemical laboratory, a non–smoking shop, a pharmacy store, a car garage, a hairdresser's store, a photocopy store, a taxi, a gym, a mall, a restaurant, a bar, a kiosk and a school. The sixteen different cases were categorized according to the location, the type of the activities taking place indoors, the number of occupants, the proximity to heavy traffic roads, the ventilation pattern etc. According to the results, the maximum particle concentration (in average 285μg m−3) was recorded at the hairdresser store while the minimum concentration was measured in the cases of the housewife and the employee in the non–smoking shop (in average 30μg m−3). The results indicated smoking as a factor which strongly influences the exposure levels of both smokers and passive smokers. Furthermore, it was found that the building ventilation pattern comprises an important factor influencing the exposure levels especially in cases of buildings with great number of visitors (resuspension) and smoking

Studying geometric structures in meso-scale flows

Geometric shapes of coherent structures such as ramp or cliff like signals, step changes and waves, are commonly observed in meteorological temporal series and dominate the turbulent energy and mass exchange between the atmospheric surface layer and the layers above, and also relate with low-dimensional chaotic systems. In this work a simple linear technique to extract geometrical shapes has been applied at a dataset which was obtained at a location experiencing a number of different mesoscale modes. It was found that the temperature field appears much better organized than the wind field, and that cliff-ramp structures are dominant in the temperature time series. The occurrence of structural shapes was related with the dominant flow patterns and the status of the flow field. Temperature positive cliff-ramps and ramp-cliffs appear mainly during night time and under weak flow field, while temperature step and sine structures do not show a clear preference for the period of day, flow or temperature pattern. Uniformly stable, weak flow conditions dominate across all the wind speed structures. A detailed analysis of the flow field during two case studies revealed that structural shapes might be part of larger flow structures, such as a sea-breeze front or down-slope winds. During stagnant conditions structural shapes that were associated with deceleration of the flow were observed, whilst during ventilation conditions shapes related with the acceleration of the flow

Observations of Local Meteorological Variability under Large-Scale Circulation Patterns over Athens, Greece

Linking synoptic circulation patterns to specific environmental problems is of significance in the Eastern Mediterranean region, which is characterized by increased seasonal climatic variability and a wealth of distinct weather patterns. This study aims to discuss the links between synoptic scale circulation, intra-day variability and sub-hourly temperature changes over Athens. Diurnal cycles of surface atmospheric variability were examined by applying Principal Component Analysis and Integral Quantities Analysis to a four months data set with surface meteorological elements. Sub-hourly temperature changes were identified by applying a simple linear technique. Principal Components, Integral Quantities and temperature change rates (geometric structures) were related with synoptic circulation categories. It was found that the presence of a Closed Low over the area results in intense along-mountain flows, whilst, after the passage of a trough, when a strong northwesterly flow is established over the area, surface recirculation flows develop. On 64% of the days, geometric structures were observed in the hourly temperature time-series, and they were found to occur across all synoptic situations. Cliff—ramps was the most common geometric structure, and step changes were found to be related with recirculation flows

A comparative study of the main mechanisms controlling indoor air pollution in residential flats

The relative contribution of the main mechanisms that control indoor air quality in residential flats was examined. Indoor and outdoor concentration measurements of different type pollutants (black carbon, SO2, O3, NO, NO2,) were monitored in three naturally ventilated residential flats in Athens, Greece. At each apartment, experiments were conducted during the cold as well as during the warm period of the year. The controlling parameters of transport and deposition mechanisms were calculated from the experimental data. Deposition rates of the same pollutant differ according to the site (different construction characteristics) and to the measuring period for the same site (variations in relative humidity and differences in furnishing). Differences in the black carbon deposition rates were attributed to different black carbon size distributions. The highest deposition rates were observed for O3 in the residential flats with the older construction and the highest humidity levels. The calculated parameters as well as the measured outdoor concentrations were used as input data of a one-compartment indoor air quality model, and the indoor concentrations, the production, and loss rates of the different pollutants were calculated. The model calculated concentrations are in good agreement with the measured values. Model simulations revealed that the mechanism that mainly affected the change rate of indoor black carbon concentrations was the transport from the outdoor environment, while the removal due to deposition was insignificant. During model simulations, it was also established that that the change rate of SO2 concentrations was governed by the interaction between the transport and the deposition mechanisms while NOX concentrations were mainly controlled through photochemical reactions and the transport from outdoors

On the variability of the surface environment response to synoptic forcing over complex terrain: a multivariate data analysis approach

Synoptic climatology relates the atmospheric circulation with the surface environment. The aim of this study is to examine the variability of the surface meteorological patterns, which are developing under different synoptic scale categories over a suburban area with complex topography. Multivariate Data Analysis techniques were performed to a data set with surface meteorological elements. Three principal components related to the thermodynamic status of the surface environment and the two components of the wind speed were found. The variability of the surface flows was related with atmospheric circulation categories by applying Correspondence Analysis. Similar surface thermodynamic fields develop under cyclonic categories, which are contrasted with the anti-cyclonic category. A strong, steady wind flow characterized by high shear values develops under the cyclonic Closed Low and the anticyclonic H–L categories, in contrast to the variable weak flow under the anticyclonic Open Anticyclone category