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| Titel |
New considerations for PM, Black Carbon and particle number concentration for air quality monitoring across different European cities |
| VerfasserIn |
C. Reche, X. Querol, A. Alastuey, M. Viana, J. Pey, T. Moreno, S. Rodríguez, Y. González, R. Fernández-Camacho, J. Rosa, M. Dall'Osto, A. S. H. Prévôt, C. Hueglin, R. M. Harrison, P. Quincey |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 13 ; Nr. 11, no. 13 (2011-07-01), S.6207-6227 |
| Datensatznummer |
250009881
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| Publikation (Nr.) |
 copernicus.org/acp-11-6207-2011.pdf |
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| Zusammenfassung |
In many large cities of Europe standard air quality limit values of
particulate matter (PM) are exceeded. Emissions from road traffic and
biomass burning are frequently reported to be the major causes. As a
consequence of these exceedances a large number of air quality plans, most
of them focusing on traffic emissions reductions, have been implemented in
the last decade. In spite of this implementation, a number of cities did not
record a decrease of PM levels. Thus, is the efficiency of air quality plans
overestimated? Do the road traffic emissions contribute less than expected
to ambient air PM levels in urban areas? Or do we need a more specific
metric to evaluate the impact of the above emissions on the levels of urban
aerosols?
This study shows the results of the interpretation of the 2009 variability of
levels of PM, Black Carbon (BC), aerosol number concentration (N) and a
number of gaseous pollutants in seven selected urban areas covering road
traffic, urban background, urban-industrial, and urban-shipping environments
from southern, central and northern Europe.
The results showed that variations of PM and N levels do not always reflect
the variation of the impact of road traffic emissions on urban aerosols.
However, BC levels vary proportionally with those of traffic related gaseous
pollutants, such as CO, NO2 and NO. Due to this high correlation, one
may suppose that monitoring the levels of these gaseous pollutants would be
enough to extrapolate exposure to traffic-derived BC levels. However, the
BC/CO, BC/NO2 and BC/NO ratios vary widely among the cities studied, as
a function of distance to traffic emissions, vehicle fleet composition and
the influence of other emission sources such as biomass burning. Thus,
levels of BC should be measured at air quality monitoring sites.
During morning traffic rush hours, a narrow variation in the N/BC ratio was
evidenced, but a wide variation of this ratio was determined for the noon
period. Although in central and northern Europe N and BC levels tend to vary
simultaneously, not only during the traffic rush hours but also during the
whole day, in urban background stations in southern Europe maximum N levels
coinciding with minimum BC levels are recorded at midday in all seasons.
These N maxima recorded in southern European urban background environments
are attributed to midday nucleation episodes occurring when gaseous
pollutants are diluted and maximum insolation and O3 levels occur. The
occurrence of SO2 peaks may also contribute to the occurrence of midday
nucleation bursts in specific industrial or shipping-influenced areas,
although at several central European sites similar levels of SO2 are
recorded without yielding nucleation episodes.
Accordingly, it is clearly evidenced that N variability in different
European urban environments is not equally influenced by the same emission
sources and atmospheric processes. We conclude that N variability does not
always reflect the impact of road traffic on air quality, whereas BC is a
more consistent tracer of such an influence. However, N should be measured
since ultrafine particles (<100 nm) may have large impacts on human health.
The combination of PM10 and BC monitoring in urban areas potentially
constitutes a useful approach for air quality monitoring. BC is mostly
governed by vehicle exhaust emissions, while PM10 concentrations at
these sites are also governed by non-exhaust particulate emissions
resuspended by traffic, by midday atmospheric dilution and by other
non-traffic emissions. |
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