Analysis and Evaluation of Selected PM sub(10) Pollution Episodes in the Helsinki Metropolitan Area in 2002

The selected re-suspension and long-range transport (LRT) episodes of PM sub(10) in the Helsinki Metropolitan Area in 2002, were analyzed. The PM sub(10) concentrations in street level air were dominated by the combustion, non-combustion and suspension emissions originating from vehicular traffic, and the LRT. PM sub(10) concentrations were measured continuously with beta -attenuation monitor. The ultrafine and fine particle number size distributions were measured continuously in Helsinki. A linear regression model was used to evaluate the LRT contribution to PM sub(2.5). Meteorological parameters and air mass back trajectories were also used to evaluate the observations. The results showed that the highest 24-h averages of PM sub(10) and PM sub(2.5) and the number of exceedances for the daily average occurred in March and April.