Comparison of the chemical composition of PM10 and PM2.5 particles collected in urban environments and volcanic areas of metropolitan Costa Rica

Se muestrearon en forma simultánea partículas PM10 y PM2,5 en ambientes urbanos y volcánicos del área metropolitana de Costa Rica, durante octubre y noviembre de 2012. En las áreas industriales y comerciales de alto flujo vehicular (La Uruca, Heredia y Belén) se presentaron concentraciones másicas significativamente superiores (42 – 29 µgm-3) de PM10 y PM2,5 en comparación con las registradas en la zona volcánica. Las concentraciones diarias de PM10 y PM2,5 obtenidas en el volcán Poas variaron entre 3 -14 µgm-3 y 2 - 11 µgm-3, respectivamente. Sin embargo, la acidez de las partículas colectadas en el Poás es mayor a las correspondientes a ambientes urbanos debido probablemente a una ocurrencia menor de tasas de neutralización. El aporte de iones secundarios resultó ser la principal contribución (40%) a la composición de las PM10 volcánicas a diferencia de las colectadas en centros urbanos. PM10 and PM2,5 were sampled simultaneously in urban and volcanic environments in the Metropolitan Area of Costa Rica from October to November 2012. Higher mass concentrations (42-29 μgm-3) of PM10 and PM2,5 were found at industrial and commercial areas with high traffic flow (La Uruca, Heredia and Belen) compared with those found in the volcanic areas. The daily concentrations of PM10 and PM2,5 obtained in the Poas Volcano ranged from 3 -14 μgm-3 and 2-11 μgm-3, respectively. However the acidity of the collected particles in the Poas volcano was higher than those sampled in urban environments probably due to a lower occurrence rate of neutralization. The contribution of secondary ions was more important to the volcanic PM10 composition (around 40%), unlike the PM10 collected in urban areas.