Adding virtual measuring stations to a network for urban air pollution mapping.

Maps of pollutants concentration are usually generated by means of interpolation and extrapolation methods. The quality of the results depends mainly of the number of permanent or temporary measuring stations. This paper deals with a method for the virtual densification of the network of stations. The method creates "virtual measuring stations". It aims at improving the quality of interpolation by increasing the number of data on pollutant concentration. The virtual stations are determined by the means of a classification method applied to each pixel of the area under concern. Discriminating elements are pollutants emission classes, land cover types, urban morphological indicators created to this purpose and distance to major roads. A first implementation was made for particulate matter (PM) for the city of Strasbourg (France) using thin-plates spline interpolation method in Arcview 9 GIS. The relative Root Mean Square Error decreases from 49% for five input stations down to 15% for the virtual stations.

Specific plant DNA adducts as molecular biomarkers of genotoxic atmospheric environments.

The general purpose of this study was to determine whether the formation of DNA addition products ('adducts') in plants could be a valuable biomarker of genotoxic air pollution. Plants from several species were exposed to ambient atmosphere at urban and suburban sites representative of different environmental conditions. The levels of NO2 and of the quantitatively major genotoxic air pollutants benzene, toluene, and xylene were monitored in parallel with plant exposure. DNA adducts were measured in bean (Phaseolus vulgaris), rye-grass (Lolium perenne), and tobacco (Nicotiana tabacum) seedlings by means of the [32P]-postlabeling method. Whereas, no correlation was found between the levels of the major genotoxic air pollutants and the total amounts of DNA adducts, individual analyses revealed site-specific and plant species-specific adduct responses, both at the qualitative and quantitative level. Among these, the amount of a specific rye-grass DNA adduct (rgs1) correlated with benzene/toluene/xylene levels above a threshold. For further characterization, rye-grass seedlings were treated in controlled conditions with benzene, toluene, xylene or their derivatives. On the other hand, in vitro DNA adduct formation assays were developed involving benzene, toluene, xylene, or their derivatives, and plant microsomes or purified peroxidase. Although in some cases, these approaches produced specific adduct responses, they failed to generate the rgs1 DNA adduct, which appeared to be characteristic for on-site test-plant exposure. Our studies have thus identified an interesting candidate for further analysis of environmental biomarkers of genotoxicity.

[Air pollution and myocardial infarction. Strasbourg France, 1984-89]. / Pollution atmosphérique et infarctus du myocarde. Strasbourg, 1984-1989.

BACKGROUND: Many studies have shown positive associations between urban air pollution, mortality and hospitalizations for cardiovascular diseases. This study tried to estimate short term effects of ambient air pollution on myocardial infarction on the basis of data collected in a morbidity registry. METHODS: The daily number of myocardial infarctions between 1984 and 1989 was supplied by the Monica registry (Bas-Rhin). The pollution variables were daily mean and maximum of hourly measures of carbon monoxyde (CO), sulfur dioxide (SO(2)), particles (PM13), nitrogen monoxyde (NO) and nitrogen dioxide (NO(2)), mean and maximum of hourly measures of ozone (O(3)) between 10 a.m. and 6 p.m. Other data were influenza epidemics, daily temperature and humidity. The analysis was a Poisson regression controlling for trend, season, meteorological factors and pollutant, using non parametric smoothing. Influence of day of week and influenza were controlled through dummy variables. RESULTS: For the hourly maximum of NO with a 5 day lag the association was statistically significant (square root relation): for an increase from percentile 25 (63 microg/m(3)) to percentile 75 (189 microg/m(3)), the RR was 1.087 (95% CI: 1.014-1.166). The association was significant during winter with a RR of 1.129 (95% CI: 1.028-1.241) for a percentile 25 (101 microg/m(3)) to percentile 75 (265 microg/m(3)) increase. A positive linear association was found with daily maximum of NO(2) during winter with a 5 day lag: the RR, for an increase from percentile 25 (59 microg/m(3)) to percentile 75 (107 microg/m(3)) was 1.095 (95% CI: 1.015-1.181). For the daily mean and maximum of O(3), a positive association was found but it was not robust. For other pollutants, no association was found. CONCLUSIONS: The association between NO(2) and coronary events, hospitalizations and mortality, has been shown in several studies but not in all. This secondary pollutant could be a proxy for small particles.