Ultrafine particles in cities

Prashant Kumar, L. Morawska, W. Birmili, P. Paasonen, M. Hu, M. Kulmala, R.M. Harrison, L. Norford, R. Britter

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343 Citations (Scopus)
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Ultrafine particles (UFPs; diameter less than 100 nm) are ubiquitous in urban air, and an acknowledged risk to human health. Globally, the major source for urban outdoor UFP concentrations is motor traffic. Ongoing trends towards urbanisation and expansion of road traffic are anticipated to further increase population exposure to UFPs. Numerous experimental studies have characterised UFPs in individual cities, but an integrated evaluation of emissions and population exposure is still lacking. Our analysis suggests that the average exposure to outdoor UFPs in Asian cities is about four-times larger than that in European cities but impacts on human health are largely unknown. This article reviews some fundamental drivers of UFP emissions and dispersion, and highlights unresolved challenges, as well as recommendations to ensure sustainable urban development whilst minimising any possible adverse health impacts.
Original languageEnglish
Pages (from-to)1-10
Number of pages10
JournalEnvironment International
Early online date4 Feb 2014
Publication statusPublished - 1 May 2014


  • City environment
  • Particle exposure
  • Health impacts
  • Particle number concentration
  • Ultrafine particles


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