Numerous studies have demonstrated the toxic effects of fine particle matter less than 2.5 mu m (PM2.5) on health of human. However, little information is available on PM2.5 ecotoxicity. We employed Caenorhabditis elegans to investigate the adverse effects of traffic-related PM2.5 on exposed animals and their progeny. Acute exposure to high concentrations of PM2.5 in the range of mg/L caused adverse effects on development, lifespan, reproduction, and locomotion behavior of nematodes. In contrast, prolonged exposure to low concentrations of PM2.5 in the range of mu g/L resulted in adverse effects on development, lifespan, reproduction, locomotion behavior, and intestinal development of nematodes. Prolonged exposure to PM2.5 could even cause adverse effects on lifespan, reproduction, locomotion behavior, and intestinal development in progeny of exposed nematodes. PM2.5 toxicity was only partially recovered in progeny of exposed nematodes. For the PM2.5 toxicity on nematodes and their progeny, we hypothesize that it might be the combinational effects of oxidative stress, damage on intestinal barrier, and abnormal defecation behavior. Our data here imply the potential toxic effects of long-term exposure to traffic-related PM2.5 on environmental organisms. Our results further highlight the possible crucial roles of biological barrier and defecation behavior in regulating the PM2.5 toxicity. (C) 2014 Elsevier B.V. All rights reserved.