Semi-continuous PM2.5 inorganic composition measurements during the Pittsburgh Air Quality Study

Ann E. Wittig, Satoshi Takahama, Andrei Y. Khlystov, Spyros N. Pandis, Susanne Hering, Brent Kirby, Cliff Davidson

Research output: Contribution to journalArticlepeer-review

59 Scopus citations


A method for semi-continuous (10min time resolution) PM2.5 nitrate and sulfate measurements, based on the humidified impaction with flash volatilization design of Stolzenburg and Hering (Environ. Sci. Technol. 34 (2000) 907), was evaluated during the Pittsburgh Air Quality Study (PAQS) from July 2001 to August 2002. The semi-continuous measurements were corrected for several operating parameters. The overall corrections were less than 10% on average, but could be quite large for individual 10min measurements. These corrections resulted in an improvement in the agreement of the measurements with the filter-based measurements, with a major axis regression relationship of y=0.83x+0.20μgm-3 and R2 of 0.84 for nitrate and y=0.71x+0.42μgm-3 and R2 of 0.83 for sulfate. The corrected semi-continuous measurements were calibrated over the entire year using collocated denuder/filter-pack-based measurements. These calibrated semi-continuous measurements are used in conjunction with temporally resolved gas-phase measurements of total (gas- and aerosol-phase) nitrate and meteorological measurements to investigate short-term phenomena at the Pittsburgh Supersite. The gas-to-particle partitioning of nitrate varied daily and seasonally, with a majority of the nitrate in the particle phase at night and during the winter months.

Original languageEnglish (US)
Pages (from-to)3201-3213
Number of pages13
JournalAtmospheric Environment
Issue number20
StatePublished - Jun 2004
Externally publishedYes


  • Atmospheric aerosols
  • Continuous monitors
  • PM nitrate
  • PM sulfate

ASJC Scopus subject areas

  • General Environmental Science
  • Atmospheric Science


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