PAH-associated health risk from ultrafine particles: an urban field study

Ultrafine particles (UFPs) are airborne particulate matter with diameters less than 100 nm. UFPs present in urban atmospheres pose a significant public health issue because they usually carry harmful substances, including toxic metals and polycyclic aromatic hydrocarbons (PAHs). Prolonged exposure to urban UFPs may result in cumulative deposition of these harmful substances in the human respiratory system, elevating the likelihood of adverse respiratory outcomes. Thus, studying UFP respiratory deposition is essential for assessing associated health risks. In this research, a set of field studies was conducted at three selected sampling sites to examine urban UFP exposure in the Greater Houston Area, Texas, USA. At each sampling site, UFP respiratory deposition measurements were performed using the Mobile Aerosol Lung Deposition Apparatus (MALDA). In addition, size-segregated UFP samples were collected and analyzed to identify and quantify harmful constituents associated with UFPs. The resulting data were used to estimate the deposited mass of PAH in human airways and to evaluate the corresponding health risks linked to urban UFP exposure. Overall, both non-carcinogenic and carcinogenic risks associated with UFP-bound PAH in the Greater Houston Area were found to remain within acceptable levels.