[Fine, ultrafine and nano- particles in the living and working setting: potential health effects and measurement of inhalation exposure].

Recently, experimental evidence has shown that exposure to very fine particles including those ultrafine or nanometric (NP, size < 100 nm) may cause severe health effects after inhalation in ambient and occupational environments (ultrafine particles in urban air, diesel emissions, welding fumes). Although the toxicological mechanisms for these effects have not yet been explained, the considerable body of existing data on occupational and environmental impact of airborne particles provides indications on the characteristics that influence toxicity and dose-response relationships. While for supermicrometric particles it is sufficient measuring exposure in terms of mass, for very fine particles, and in particular for NP, the characteristics that are more biologically relevant include the number, size, surface area, shape, solubility, and chemical reactivity. The rapidly developing field of nanotechnology, based on the use of a variety of NP (engineered or intentionally produced and with unique and specific properties), will certainly create new exposure scenarios which actually are largely unknown. The concern of potential health impact from the exposure to NP, during the last years has accelerated the development of systems for characterizing the exposures associated to the different potential sources of particles in the submicrometer and nanometer size ranges in both the environment and the workplace. In this review the current problems for characterizing the biologically relevant exposure to very fine and nanometric particles are discussed mainly in the context of occupational aerosols.