Indoor and outdoor PM mass and number concentrations at schools in the Athens area.

Simultaneous indoor and outdoor PM10 and PM2.5 concentration measurements were conducted in seven primary schools in the Athens area. Both gravimetric samplers and continuous monitors were used. Filters were subsequently analyzed for anion species. Moreover ultrafine particles number concentration was monitored continuously indoors and outdoors. Mean 8-hr PM10 concentration was measured equal to 229 +/- 182 microg/m3 indoors and 166 +/- 133 microg/m3 outdoors. The respective PM2.5 concentrations were 82 +/- 56 microg/m3 indoors and 56 +/- 26 microg/m3 outdoors. Ultrafine particles 8-h mean number concentration was measured equal to 24,000 +/- 17,900 particles/cm3 indoors and 32,000 +/- 14,200 particles/cm3 outdoors. PM10 outdoor concentrations exhibited a greater spatial variability than the corresponding PM2.5 ones. I/O ratios were close or above 1.00 for PM10 and PM2.5 and smaller than 1.00 for ultrafine particles. Very high I/O ratios were observed when intense activities took place. The initial results of the chemical analysis showed that SO4(-2) accounts for the 6.6 +/- 3.5% of the PM10 and NO3(1) for the 3.1 +/- 1.4%.The corresponding results for PM2.5 are 12.0 +/- 7.7% for SO4(-2) and 3.1 +/- 1.9% for NO3-. PM2.5 SO4(-2) indoor concentrations were highly correlated with outdoor ones and the regression line had the largest slope and a very low intercept, indicative of no indoor sources of fine particulate SO4(-2). The results of the statistical analysis of indoor and outdoor concentration data support the use of SO4(-2) as a proper surrogate for indoor PM of outdoor origin.

Levels of ultrafine particles in different microenvironments--implications to children exposure.

Indoor and outdoor ultrafine particles (UFPs) (0.01 to greater than 1 microm) concentration levels were examined in the area of Athens during cold period of 2003 and 2004. Seven primary schools, located in areas with different characteristics of urbanization and traffic density, as well as a typical suburban residence, were monitored. Moreover, in-vehicle concentration levels, while driving along major avenues and in the heavy-trafficked centre of Athens, were measured (mean route duration: 45 min). UFPs number concentration was monitored by condensation particle counter (model CPC 3007), with a logging time interval of 1 min. The highest mean indoor concentrations were observed in a small carpet-covered library and a teachers' office (8-hour mean equal to 52.6x10(3) particles/cm(3) and 50.2x10(3) particles/cm(3), respectively), at the same school unit. The highest outdoor concentrations (8-hour mean equal to 36.9x10(3) particles/cm(3) and 38.8x10(3) particles/cm(3)) were measured at two schools, both affected by heavy traffic. Finally, the highest in-vehicle concentrations (148.0x10(3)-173.0x10(3) particles/cm(3)) were measured in central commercial areas of Athens during, on average, 55 min drives. Indoor-to-outdoor concentration (I/O) ratios were below 1.00 at all sites. The largest ratio (0.88) was observed in the residence, during a day when there was cleaning activity in the room monitored. Outdoor concentrations diurnal cycles, both outside the schools and the residence, were closely related to traffic. Indoor concentrations inside schools were relatively stable in classrooms. Nevertheless, number concentrations exhibited variability when there were significant changes in room occupancy. Diurnal variation of indoor concentrations at the residence followed the respective outdoor one with a delay of 1 h or less, in the absence of strong indoor sources, indicating the major contribution of outdoor UFPs to the indoor concentration levels. The present work is the first effort to examine UFPs indoor and outdoor concentration levels in the area of Athens. The obtained concentration data give an insight on the concentration levels to which children may be exposed. They may be also very useful in epidemiological studies, in order to estimate children total personal exposure though the calculation of exposures received in different microenvironments. This kind of studies may contribute to the design of effective policies and mitigation measures for the protection of public health.

Particulate matter and black smoke concentration levels in central Athens, Greece.

This study presents the statistical analysis of PM(10) and PM(2.5) concentrations (measured at a central site, in the Athens area), along with black smoke (BS) data, for a 2-year period. The biennial average concentrations of PM(10) and PM(2.5) were 75 and 40 microg m(-3). The respective average concentration of BS, as estimated by the OECD method, was 108 microg m(-3). Severe exceedances of the PM(10) air quality standards were recorded. The seasonal variation of PM(10) and BS was less pronounced than the variation of PM(2.5), which concentration was elevated by 14.2% during the cold period. Concentrations of all three pollutants were significantly lower during weekends; however, PM(2.5) and BS displayed a more uniform weekly distribution pattern. PM(10) particles were found to be almost equally comprised by PM(2.5) and PM(10-2.5) particles (PM(2.5)/PM(10) ratio=0.53+/-0.09 microg/m(3)). The average PM(10)/BS value was found lower than unity revealing the inappropriateness of the used reflectance conversion method, for the estimation of mass-equivalent BS concentrations, in the study area, where diesel-powered vehicles mainly control emissions of light-absorbing substances. Important reductions in concentrations were observed during days when drivers of diesel-powered taxies and transportation buses went on strike (reaching 40% for BS). Calm wind conditions were found to have an incremental effect on particle concentrations and were also associated with the appearance of persistent episodic events. Increased PM levels were also observed during southern-southwestern wind flows while significantly lower-than-average concentrations were measured during precipitation events. Separate regression analyses were performed for PM(10), PM(2.5) with BS and NO(x) as independent variables, in an attempt to estimate the relative contribution of specific source types (diesel-powered vehicles) to measured particle levels. The contribution of the diesel-exhaust component to PM(10) mass was estimated at 49.9%, while the corresponding contributions to PM(2.5) mass concentrations was 53.8%. These results may have important implications with the oncoming decision of national authorities to allow the purchase of diesel-powered private cars to the residents of the Greater Athens Area, which was forbidden up to this day.

Exposure to carbon monoxide in the Athens urban area during commuting.

An extensive survey has been designed to provide detailed information on carbon monoxide (CO) concentration in the main transport modes and along heavy traffic routes in the Athens urban area. Specifically the study identifies the main factors affecting CO exposure during commuting. Several portable, electrochemical CO monitors (Solomat's MPM4100), were used to record the in-vehicle CO concentrations every 15 s. Measurements were performed during rush hour periods. Field monitoring was conducted in summer 1998 and winter 1998-1999. Exposure estimates were compared to WHO guidelines. The findings showed that the mean CO level over trips of 30 min was 21.4 ppm for private car against 10.4, 9.6, 4 and 11.5 ppm for bus, trolley, electric train and pedestrians, respectively. Transport mode, route, monitoring period and season had a significant influence on the measured CO concentrations. The study points out the importance of microenvironmental monitoring, instead of using fixed-site data in assessing commuter's CO exposure.