The concentration of iron in real-world geogenic PM10 is associated with increased inflammation and deficits in lung function in mice.

BACKGROUND: There are many communities around the world that are exposed to high levels of particulate matter <10 µm (PM10) of geogenic (earth derived) origin. Mineral dusts in the occupational setting are associated with poor lung health, however very little is known about the impact of heterogeneous community derived particles. We have preliminary evidence to suggest that the concentration of iron (Fe) may be associated with the lung inflammatory response to geogenic PM10. We aimed to determine which physico-chemical characteristics of community sampled geogenic PM10 are associated with adverse lung responses. METHODS: We collected geogenic PM10 from four towns in the arid regions of Western Australia. Adult female BALB/c mice were exposed to 100 µg of particles and assessed for inflammatory and lung function responses 6 hours, 24 hours and 7 days post-exposure. We assessed the physico-chemical characteristics of the particles and correlated these with lung outcomes in the mice using principal components analysis and multivariate linear regression. RESULTS: Geogenic particles induced an acute inflammatory response that peaked 6 hours post-exposure and a deficit in lung mechanics 7 days post-exposure. This deficit in lung mechanics was positively associated with the concentration of Fe and particle size variability and inversely associated with the concentration of Si. CONCLUSIONS: The lung response to geogenic PM10 is complex and highly dependent on the physico-chemical characteristics of the particles. In particular, the concentration of Fe in the particles may be a key indicator of the potential population health consequences for inhaling geogenic PM10.

Variability and consistency in lung inflammatory responses to particles with a geogenic origin.

BACKGROUND AND OBJECTIVE: Particulate matter <10 µm (PM10 ) is well recognized as being an important driver of respiratory health; however, the impact of PM10 of geogenic origin on inflammatory responses in the lung is poorly understood. This study aimed to assess the lung inflammatory response to community sampled geogenic PM10 . METHODS: This was achieved by collecting earth material from two regional communities in Western Australia (Kalgoorlie-Boulder and Newman), extracting the PM10 fraction and exposing mice by intranasal instillation to these particles. The physicochemical characteristics of the particles were assessed and lung inflammatory responses were compared to control particles. The primary outcomes were cellular influx and cytokine production in the lungs of the exposed mice. RESULTS: The physical and chemical characteristics of the PM10 from Kalgoorlie and Newman differed with the latter having a higher concentration of Fe and a larger median diameter. Control particles (2.5 µm polystyrene) caused a significant influx of inflammatory cells (neutrophils) with little production of proinflammatory cytokines. In contrast, the geogenic particles induced the production of MIP-2, IL-6 and a significant influx of neutrophils. Qualitatively, the response following exposure to particles from Kalgoorlie and Newman were consistent; however, the magnitude of the response was substantially higher in the mice exposed to particles from Newman. CONCLUSIONS: The unique physicochemical characteristics of geogenic particles induced a proinflammatory response in the lung. These data suggest that particle composition should be considered when setting community standards for PM exposure, particularly in areas exposed to high geogenic particulate loads.

Extracting dust from soil: Improved efficiency of a previously published process.

A previously published procedure describing how to simply and cheaply extract a sufficient quantity of dust particles sized smaller than 10µm (PM(10)) from soil to be used in air quality analysis has been modified and improved. These modifications are described in detail and are significant because they will enable extraction of a greater quantity of the PM(10) fraction for a given soil sample, in less time and without the need for building specialised equipment. Less water is also used in the modified procedure, and thus a smaller risk of dissolution of metals of interest.