A systematic review of outdoor airborne asbestos concentrations in urban and rural areas

Asbestos is a group of minerals that, due to their distinctive physical properties, has been widely used across numerous industries. The extensive historical global use together with the persistence of the fibers, have led to their widespread presence in various environments. The degradation of asbestos-containing materials, such as asbestos-cement sheets for roofing, may contribute to the dispersion of asbestos fibers into the ambient air. Asbestos is carcinogenic, and low levels of exposure in the environment have been linked to cancer. The objective of this review is to investigate to what extent populations may be exposed to outdoor airborne asbestos in urban and rural areas, where asbestos-containing materials in buildings or asbestos-containing automobile parts are the main sources. We identified relevant studies by searching in three databases: PubMed, EMBASE, and Web of Science. Included studies were required to provide a predefined set of details regarding the sampling procedures and analytical methods employed. Studies were excluded if measurements had been conducted in areas with nearby asbestos-related industries or high levels of natural occurrence of asbestos. We identified 22 articles about airborne asbestos concentration in the outdoor environment, of which nine presumed asbestos-containing materials from buildings to be the main source. Our review indicates that low, but non-negligible, levels of airborne asbestos fibers may be present in the outdoor environment. The review highlights the need for further research into the levels of airborne asbestos in rural and urban areas, as well as the need for standardized methods to measure environmental exposure.