Acute effects of air pollution on pediatric asthma exacerbation: evidence of association and effect modification.

We investigated the short-term effects of particulate matter with aerodynamic diameter <10 µg/m(3) (PM(10)), sulfur dioxide (SO(2)), nitrogen dioxide (NO(2)) and ozone (O(3)) on pediatric asthma emergency admissions in Athens, Greece over the period 2001-2004. We explored effect modification patterns by season, sex, age and by the presence of desert dust transported mainly from the Sahara area. We used daily time-series data provided by the children's hospitals and the fixed monitoring stations. The associations were investigated using Poisson regression models controlling for seasonality, weather, influenza episodes, day of the week and holiday effects. A 10 µg/m(3) increase in PM(10) was associated with a 2.54% increase (95% confidence interval (CI): 0.06%, 5.08%) in the number of pediatric asthma hospital admissions, while the same increase in SO(2) was associated with a 5.98% (95% CI: 0.88%, 11.33%) increase. O(3) was associated with a statistically significant increase in asthma admissions among older children in the summer. Our findings provide limited evidence of an association between NO(2) exposure and asthma exacerbation. Statistically significant PM(10) effects were higher during winter and during desert dust days, while SO(2) effects occurred mainly during spring. Our study confirms previously reported PM(10) effects on emergency hospital admissions for pediatric asthma and further provides evidence of stronger effects during desert dust days. We additionally report severe effects of SO(2), even at today's low concentration levels.

Temporal evolution of sulfur dioxide and nitrogen oxides in the city of Volos, Greece.

The goal of this work is the analysis of air quality levels in the area of Volos, a city of average size on the eastern seaboard of Central Greece. For this purpose, concentration measurements of sulfur dioxide, nitrogen oxide, and nitrogen dioxide, for a 4-year period (2001-2004) are analyzed. Air pollution data were obtained by a monitoring station, fully automated, which was established by the Hellenic Ministry of the Environment, Physical Planning, and Public Works, in order to measure air pollution levels in Volos, a medium-sized city, which faces the effects of industrialization. The main conclusions from the statistical analysis of the 4-year measurements of hourly SO(2), NO(2), and NO concentrations in the city of Volos, showed that the mean seasonal variation of the examined air pollutant concentration presents a minimum during the warm period of the year and a maximum during the cold period. Although the local geomorphology and meteorology encourage particularly the accumulation of air pollutants, the analysis shows that the SO(2) and NO(2) concentration levels remain lower than corresponding thresholds for human health protection set by the European Union, in this urban measuring site, during the examined period. The application of harmonic analysis revealed the difference between the annual variation of the SO(2) and NO(x) concentrations. Regarding NO(x), the variation is mainly due to the first harmonic term (anthropogenic factor), while the SO(2) variation is interpreted by the two harmonic terms, which represent the anthropogenic and meteorological factors, respectively.

Temporal evolution of the sulphur oxides emissions from the Greek electricity generation sector.

The Greek electricity production sector is based--as far back as the early 60s--on the usage of local lignite and imported heavy-oil. Hence the electricity production process is assumed responsible for a significant contribution to air pollution, including 80% of the national sulphur dioxide emissions. In this context, an extensive and thorough analysis is carried out concerning the SO2 effluents coming from the electricity generation sector during the 1995-2002 period. For this purpose, the available long-term official measurements are taken into consideration and analysed in depth. According to this analysis, the SO2 emissions factor ratio between Southern Greece and Northern Greece lignite fired stations is in the order of 25:1. Additionally, one may definitely state that there is a considerable surcharge of sulphur oxides released by the Greek electricity production system, which although showing a fairly decreasing tendency, is still above the 8.5gr kWh(-1) consumed. Finally, the positive contribution of the natural gas, gradually replacing other fuels, and the operation of a new desulphurisation unit in S. Greece are clearly counterbalanced by the significant and constant annual electricity consumption amplification of the last decade.

Nine-year trend of air pollution by CO in Athens, Greece.

Air quality data obtained by the Athens air pollution monitoring system from the nine-year period started in 1986 were analysed to determine time variations and the effect of various meteorological parameters on air quality by CO. From the ten monitoring stations measuring CO, the station located in a street with high traffic was selected since this site had the longest time record and presented the highest values of CO during the period examined. The time variations show that higher concentrations of CO were measured during the winter months, on working days and between 09.00 and 23.00 hours. The long-term trend shows a definite decline of CO concentrations after 1990 resulting from the substitution of gasoline-powered vehicles with vehicles equipped with three-way catalysts. Finally, it was found that during days with calm or S-SW blowing light winds the CO concentrations presented their higher values.