Arsenic speciation in aerosols of a respiratory therapeutic cave: A first approach to study arsenicals in ultrafine particles.

Arsenic is ubiquitous in the environment and of special concern due to its varying toxicity depending on the chemical form present. Less is known about arsenic in air, especially about organoarsenicals, their sources and fate. There is also a lack of knowledge regarding arsenic in airborne nanoparticles that are critical for understanding with respect to human health effects due to their size. Here we show results from an arsenic speciation analysis in size-resolved airborne particles with aerodynamic diameters down to 15 nm. Analysis of aerosols from a respiratory therapeutic cave showed temporarily higher concentrations of trimethylarsine oxide than inorganic arsenic and substantial amounts of organoarsenicals, especially in smaller particles. Our method provides guidance for future studies investigating arsenicals in ultrafine particles and their health implications. Furthermore, the method developed can be used to widely monitor particle-bound organoarsenicals to fully understand the importance of As biovolatilization in the environment.