**Acknowledgement**

The authors are grateful to funding from Directorate of Research and Postgraduate Studies, Sokoine University of Agriculture (SUA)-Tanzania; Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)-Brazil; and Instituto Nacional de Ciência e Tecnologia, de Energia e Ambiente (INCT-E&A), Instituto de Química, Universidade Federal da Bahia (UFBA)-Brazil. We also wish to acknowledge Mr. Filbert T. Sogomba (SUA) for help in logistics and collection of aerosol samples and Cibele Cristina de Araújo Soares (UFBA) for PM mass measurements.
