A mobile monitoring method for the screening of vehicle-movement-induced airborne erionite from roads in high-development residential areas

Abstract

Erionite, a known carcinogenic zeolite, is prevalent in the rock strata below some parts of New Zealand. It is thought that erionite or other elongated mineral particles (EMPs) could be dispersed into the air at a concentration that is potentially harmful. Currently, there is limited understanding of the number of fibres entering the atmosphere or knowledge of the spatial variability of fibrous mineral concentrations across airsheds. It is not known if fibrous materials, when present in excavated material, are resuspended from roads and, if so, whether they remain in a ‘fibrous' form. To help answer these questions, this research describes an on-road vehicle measurement campaign involving the sampling of road dust using a portable device consisting of a pump fitted with a sampling filter. The device was fixed to a moving vehicle traveling along routes through townships currently experiencing significant levels of development and excavation activity. Erionite is known to exist close to the surface, and thus could potentially be liberated into the air during excavation. Excavated material which is transported along these routes also poses a risk. Filters were analyzed using a combination of microscopic techniques consisting of both visual morphology and elemental analysis. The methodology was successful in helping to identify EMPs, including what appears to be erionite, as well as fragments of other fibrous material within the resuspended road dust. The measurement technique could be used as a screening tool to identify areas where EMP's pose a potential risk due to excavation activity.