This work aimed to characterize chemically and morphologically particulate matter (PM2.5 and PM10) collected in the south and west zones of the city of Rio de Janeiro and in the metropolitan region, using techniques such as ion chromatography (IC), inductively coupled plasma mass spectrometry (ICP-MS) and Scanning electron microscopy- energy dispersive spectrometry (SEM-EDX). Annual mean concentrations of PM2.5 between 7,40 +/- 3,96 microgram m-3 e 17,4 +/- 7,38 microgram m-3 were measured during the years 2015 and 2018, which were lower than the intermediateair quality standard established by CONAMA, with the highest annual averages recorded during 2016, the year in which the Olympic Games were held. In addition, toxicological tests were performed with C. elegans to evaluate the effects of exposure to particulate matter (PM) in the different size fractions. Results of the chemical analysis showed that PM at all collection sites consists mainly of ionic species such Cl- , NO3 - , Na+ and SO4 2- and elements such as V, Ni, Cu, Cd, Sn and Pb, being determined only significant variations (p less than 0,05) in the concentrations of SO4 2- , NO3 - , Na+ , Cu, and Sn, between the studied periods. Based on the results of the SEM-EDX analysis, atmospheric particles were classified according to their morphology – Soot, spherical, biological and minerals- and according to their elemental composition – particles with sulfur, chlorine and iron content. Finally, toxic effects were observed by exposure C. elegans organisms to PM10 and PM2.5, altering physiological parameters (e.g growth and reproduction) and promoting antioxidant mechanisms responses, as a result of oxidative stress generated by compounds present in the PM.