Chemical characterization and source apportionment of PM10 and PM2.5 in the metropolitan area of Costa Rica, Central America

PM10 and PM2.5 levels, concentrations of major ionic components, trace elements, and organic and elemental carbon were evaluated from samples collected in 4 sites (industrial, commercial and residential zones) located in the metropolitan area of Costa Rica. The annual mean PM levels were higher in high traffic-commercial (HE-01) and industrial (BE-02) sites, 55 mu g m(-3) and 52 mu g m(-3) for PM10 and 37 mu g m(-3) and 36. g m(-3) for PM2.5, respectively. The major components of PM2.5 were organic matter (OM) and elemental carbon (EC) (44.5-69.9%), and secondary ions (16.1-27.2%), whereas the major components of PM10 were OM+EC (32.7-59.4%), crustal material (23.5-35.6%) and secondary ions (11.4-26.9%). For the most of the sampling sites, PM10 and PM2.5 concentrations were lower during the dry season and increased gradually in the rainy season due to wind patterns. PMF model identified 8 principle sources for PM10 and PM2.5 in the industrial site (crustal, secondary sulfate, secondary nitrate, secondary organic, traffic, sea-salt aerosols, industrial and oil combustion), 6 and 5 sources in commercial and residential sites, respectively. The source contributions showed a clear seasonal pattern for all the sites.