Time-resolved number concentrations and size distribution of aerosol particles in an urban road tunnel

Imre Salma, Tibor Borsós, Pasi Aalto, Markku Kulmala

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We used flow-switching type differential mobility particle sizer in a diameter range of 6-1000 nm and vehicle counting detectors with a time resolution of 10 min for 15 days in July 2010 in the Castle District Tunnel, Budapest. The total particle number concentrations varied from 5.1 × 10 3 to 465 × 10 3 cm -3 with a median of 143 × 10 3 cm -3. The median was greater by a factor of 12 than that for the urban ambient air. The mean (± SD) contribution of ultrafine particles to the total particle number was 85% ± 1%, which is significantly greater than for the urban ambient air. Diurnal variations in the number concentrations in the tunnel on workdays exhibited different time pattern than the traffic, which was explained by ventilation. Number size distributions of particles were resolved into Aitken and accumulation modes with the overall median diameters of 33 and 86 nm, respectively. The mean Aitken mode/accumulation mode concentration ratio was 3.6.

Original languageEnglish
Pages (from-to)262-272
Number of pages11
JournalBoreal Environment Research
Issue number4
Publication statusPublished - Aug 5 2011


ASJC Scopus subject areas

  • Ecological Modelling
  • Agricultural and Biological Sciences (miscellaneous)
  • Pollution
  • Atmospheric Science

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