Identification of the vehicular emission contribution to PM 2.5 mass concentration in six brazilian cities - Andrade, Maria de Fátima; Miranda, Regina Maura de; Fornaro, Adalgiza; Kerr, Américo Adlai Franco Sansigolo; André, Paulo Afonso de; Saldiva, Paulo Hilário Nascimento (AAAR10: Air Pollution and Health: Bridging the Gap from Sources and Health Outcomes, 2010)