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Title:
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Ultrafine particles in four European urban environments: Results from a new continuous long-term monitoring network
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Author(s):
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Hofman, J.; Staelens, J.; Cordell, R.; Stroobants, C; Zikova, N.; Hama, S.M.L.; Wyche, K.P.; Kos, G.P.A.; Zee, S.C. van der; Smallbone, K.L.; Weijers, E.P.; Monks, P.; Roekens, E.
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Published by:
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Publication date:
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ECN
Environment & Energy Engineering
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9-5-2016
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ECN report number:
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Document type:
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ECN-W--16-017
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Article (scientific)
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Number of pages:
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16
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Published in: Atmospheric Environment (Elsevier), , 2016, Vol.136, p.68-81.
Abstract:
To gain a better understanding on the spatiotemporal variation of ultrafine particles (UFPs) in urban
environments, this study reports on the first results of a long-term UFP monitoring network, set up in
Amsterdam (NL), Antwerp (BE), Leicester (UK) and London (UK). Total number concentrations and size
distributions were assessed during 1e2 years at four fixed urban background sites, supplemented with
mobile trailer measurements for co-location monitoring and additional short-term monitoring sites.
Intra- and interurban spatiotemporal UFP variation, associations with commonly-monitored pollutants
(PM, NOx and BC) and impacts of wind fields were evaluated. Although comparable size distributions
were observed between the four cities, source-related differences were demonstrated within specific
particle size classes. Total and size-resolved particle number concentrations showed clear traffic-related
temporal variation, confirming road traffic as the major UFP contributor in urban environments. New
particle formation events were observed in all cities. Correlations with typical traffic-related pollutants
(BC and NOx) were obtained for all monitoring stations, except for Amsterdam, which might be attributable
to UFP emissions from Schiphol airport. The temporal variation in particle number concentration
correlated fairly weakly between the four cities (rs ¼ 0.280.50, COD ¼ 0.280.37), yet improved
significantly inside individual cities (rs ¼ 0.590.77). Nevertheless, considerable differences were still
obtained in terms of particle numbers (20e38% for total particle numbers and up to 49% for size-resolved
particle numbers), confirming the importance of local source contributions and the need for careful
consideration when allocating UFP monitoring stations in heterogeneous urban environments.
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