To date,legislation,research and development have focused on the reduction of the quantity of soot emission,yet neglected the question of how changes in soot quality may change its interaction with the biosphere.We present the microstructure of low-emission soot particles studied by means of high-resolution transmission electron microscopy and the inflammatory response in vitro of human monocyte-derived macrophage cells(MDMs).Macrophages,also known as antigen presenting cells,are the primary and most important cells of immune system that react against all foreign bodies.When these cells get in contact with particles or pathogens,they become activated and secrete a lot of chemical mediators of inflammation,very aggressive against foreign molecules or particles.