Particulate matter physico-chemical characterization and in vitro toxicological effects

Particulate matter (PM) is one of the most relevant environment-related health issues all over the world since high concentrations of this pollutant are registered in cities from all the continents. In this chapter, the physicochemical properties of PM will be described also in relation to relevant sources of particles emission. PM is a complex mixture of liquid and solid particles with different size, from few nanometers up to some micrometers, with a complex chemical composition, comprising polycyclic aromatic hydrocarbons, metals ions and other organic and inorganic compounds. PM physicochemical properties are of pivotal relevance in understanding the particles potential impact on human health. The comprehension of the mechanisms of action of airborne particulates is a primary objective of toxicologists working on biological models. In vitro systems are suitable alternatives to study the effects of PM on cells representative of human tissues in the attempt to identify the mechanistic relations between PM exposure and health effects. The airways are the primary target of PM since exposure happens mainly through inhalation. Main biological processes triggered by PM in human lung cells are inflammation, DNA damage, and oxidative stress. Recently the role of PM in inducing epigenetic modifications in exposed cells has been evidenced. These PM-induced effects will be here described evidencing their importance for human diseases.