Nanoparticles in urban air: A very small problem

The human body is exposed to atmospheric pollutants on a daily basis. Breathing is the most effective route of airborne contaminant entry into the human body (BéruBé́ et al., 2008), meaning our lungs and airways take the full force of this exposure. Recent pollutant research has focused on how the
smallest particles appear to be responsible for the greatest health effects, with the main focus placed on nanoparticles. Nanoparticles are defined as particles with at least one dimension under 100 nm (BéruBé et al., 2008). In order to put this into a biological perspective, the smallest human virus is 20 nm in diameter and is able to translocate freely throughout the body. In parallel, nanoparticles
smaller than 20 nm (which are commonly found in urban air; Shi et al., 2001) could have the same translocation and deposition potentials; biological factors that currently remain unknown (Gwinn & Vallyathan, 2006).