Concentrations and estimated soot content of PM sub(1) , PM sub(2) sub(.) sub(5) , and PM sub(1) sub(0) in a subarctic urban atmosphere

• Published in: Environmental science & technology Vol. 34; no. 10; pp. 1919 - 1925
• Main Authors: Vallius, Marko J, Ruuskanen, Juhani, Mirme, Aadu, Pekkanen, Juha
• Format: Journal Article
• Language: English
• Published: 01.01.2000
• Subjects: Helsinki, Finland
• ISSN: 0013-936X

Mass concentrations of ambient particulate matter were measured in terms of daily average values of PM sub(1) , PM sub(2) sub(.) sub(5) , and PM sub(1) sub(0) for 6 months during the winter of 1996-1997 at a fixed sampling site in Helsinki, Finland, along with meteorological parameters and particle number concentrations in the size range 0.01-1 mu m. In addition, the PM filters were subjected to reflectometric analysis to determine absorption coefficients for the various fractions of urban particulate matter. The data were divided into two periods (winter and spring) in order to study more closely seasonal phenomena that have an effect on air pollution patterns. The variations in PM sub(1) sub(0) and PM sub(2) sub(.) sub(5) concentrations differed in pattern during resuspended dust episodes, whereas those in PM sub(1) concentrations followed those in PM sub(2) sub(.) sub(5) fairly well throughout the 6-month measurement period. Thus it seems that PM sub(1) does not provide much additional information on mass concentrations relative to PM sub(2) sub(.) sub(5) . Number concentrations in the ultrafine particle size range from 0.01 to 0.1 mu m, especially in wintertime, were much better correlated with absorption coefficients than with any of the three PM mass-based concentrations, indicating that Black Smoke particles are related to that size range. The results also indicate that coarse particle concentrations in ambient air are affected more by seasonal factors than are fine particle concentrations.