“…However, they are unlikely to maintain their starting sizes, due to the high tendency to coagulate/accumulate. UFPs can derive from autovehicular traffic emissions Marini et al, 2015), from the use of fuels used in different types of heating systems (Stabile et al, 2018;Jiang et al, 2019), as well as from the oil industry and other industrial processes (Fernández-Camacho et al, 2012;Borrow et al, 2018;Wang et al, 2018), including incineration and waste treatment plants (Buonanno et al, 2010(Buonanno et al, , 2011Buonanno & Morawska, 2015;). In recent years, a growing number of studies have reported UFP concentration values expressed as the number of particles per cubic centimeter; in most cases, where the aerosol size distribution was reported, it was found that UFPs represented the most conspicuous part in terms of numerical concentration (Manigrasso & Avino, 2012;Manigrasso et al, 2013).…”