To date, diesel particulate matter (DPM) has been described as aggregates of spherule particles with a smooth appearing surface. We have used a new colour confocal microscope imaging method to study the 3D shape of diesel particulate matter (DPM); we observed that the particles can have sharp jagged appearing edges and consistent with these findings, 2D light microscopy demonstrated that DPM adheres to human lung epithelial cells. Importantly, the slide preparation and confocal microscopy method applied avoids possible alteration to the particles’ surfaces and enables colour 3D visualisation of the particles. From twenty-one PM10 particles, the mean (standard deviation) major axis length was 5.6 (2.25) μm with corresponding values for the minor axis length of 3.8 (1.25) μm. These new findings may help explain why air pollution particulate matter (PM) has the ability to infiltrate human airway cells, potentially leading to respiratory tract, cardiovascular and neurological disease.

We present initial results from a novel high resolution confocal microscopy study of the 3D surface structure of volcanic ash particles from two recent explosive basaltic eruptions, Eyjafjallajökull (2010) and Grimsvötn (2011), in Iceland. The majority of particles imaged are less than 100μm in size and include PMs, known to be harmful to humans if inhaled. Previous studies have mainly used 2D microscopy to examine volcanic particles. The aim of this study was to test the potential of 3D laser scanning confocal microscopy as a reliable analysis tool for these materials and if so to what degree high resolution surface and volume data could be obtained that would further aid in their classification. First results obtained using an Olympus LEXT scanning confocal microscope with a ×50 and ×100 objective lens are highly encouraging. They reveal a range of discrete particle types characterised by sharp or concave edges consistent with explosive formation and sudden rupture of magma. Initial surface area/volume ratios are given that may prove useful in subsequent modelling of damage to aircraft engines and human tissue where inhalation has occurred.

The effects of trace element deficiencies in lambs, particularly zinc, copper, cobalt and selenium, include decreased growth rates and increased mortality. However, trace element supplementation of sheep reared under extensive conditions has several logistical problems.Two trials were designed to investigate the effect of a zinc, cobalt and selenium soluble glass bolus on the trace element status of out-wintered ewe lambs. In trial 1 600 8-month-old ewe lambs (500 Scottish Blackface and 100 North Country Cheviots) were allocated to two treatment groups; 300 were treated with a zinc, cobalt and selenium soluble glass bolus (zinc) and 300 were untreated (control). In trial 2, 315 8-month-old Scottish Blackface ewe lambs were allocated to three treatments: 105 were treated with the zinc, cobalt and selenium soluble glass bolus (zinc), 105 were treated with a copper, cobalt and selenium soluble glass bolus (copper) and the remaining 105 were untreated (control). Blood samples were collected immediately prior to giving boluses and again after approximately 4 months. These were assessed for zinc (plasma zinc concentration), cobalt (serum vitamin B12concentration), selenium (erythrocyte glutathione peroxidase activity) and copper status (plasma copper concentration, caeruloplasmin, amine oxidase and superoxide dismutase activity and calculation of the ratio between the caeruloplasmin and plasma copper).The zinc bolus in both trials significantly increased the plasma zinc concentrations (P< 0·001 andP< 0·01 respectively), erythrocyte glutathione peroxidase activities (P< 0·001) and serum vitamin B12concentrations (P< 0·001). The copper bolus also significantly increased the erythrocyte glutathione peroxidase activities (P< 0·001) and serum vitamin B12concentrations (P< 0·001) when compared with the controls but were not significantly different from the zinc group. The copper bolus significantly increased all of the copper status indicators (P< 0·01) when compared with the control and zinc groups. However, in trial 1 when only the zinc and control groups were compared, the zinc bolus significantly increased the ratio (P< 0·001) and serum caeruloplasmin (P< 0·001) and erythrocyte superoxide dismutase (P< 0·01) activities. These responses were not observed in trial 2 with the erythrocyte superoxide dismutase being significantly reduced in the zinc group when compared with the control group (P< 0·001).The zinc, cobalt and selenium soluble glass bolus increased the status of all three trace elements consistently for a period of at least 100 days. The increases of cobalt and selenium status were similar to those achieved using the copper, cobalt and selenium bolus, which also increased the copper status of the sheep.

Air pollution in cities is associated with adverse health conditions; however, the underlying reasons are poorly understood. Previous particulate matter (PM) imaging studies have mostly used 2D microscopic techniques. In this study, the 3D appearances of roadside and underground railway station airborne PMs and the elemental characteristics of underground station PM were examined. Roadside and underground station PMs were collected using a cyclone particulate matter collection system. The 3D structures of the PMs were examined using an Olympus LEXT OLS4100 confocal microscope. Elemental characteristics of underground railway station PM were evaluated with a Zeiss EVO 50 scanning electron microscope (SEM) in backscattered electron (BSE) mode. Confocal microscopy of both PM sources indicated some particles can have sharp appearing edges. The longest axis length of roadside particles had a median (range) of 4.0 (1.3 to 6.6) μm and height of 1.4 (0.3 to 2.1) μm. SEM imaging of underground railway station PM was consistent in appearance and size with confocal imaging; BSE mode indicated compositions primarily of iron, calcium, and silicon. In conclusion, we observed that some roadside and underground railway station PMs can have sharp appearing surfaces from 3D confocal microscopy. SEM imaging of underground railway station PM was consistent with confocal microscopy and enabled elemental analysis.

&lt;p&gt;While studies have shown adverse health effects associated with volcanic eruptions are thought to result from resultant gases and ash particle clouds, the precise reasons remain unclear. However, the shape of particles has previously been shown to influence their ability to adhere to human cancer cells (He and Park 2016). Furthermore grain size and the presence of silica are thought to be important in understanding respiratory effects associated with volcanic ash particles.&lt;/p&gt;&lt;p&gt;We have previously shown that volcanic ash particles can have sharp appearing surface features from 3D confocal microscopy (Wertheim et al. 2017). The aim of this study was to examine the 3D appearance, chemistry and adherence to cells of volcanic ash particles from the September 2021 La Palma eruption in particles of size PM&lt;sub&gt;10 &lt;/sub&gt;as they are considered of particular interest in respiratory conditions. Volcanic ash particles collected from the first day of the eruption were imaged using confocal scanning laser microscopy and scanning electron microscopy in order to assess their 3D appearance and geometry. In addition, 2D shape and elemental analysis, obtained from secondary and backscattered electron imaging, was performed to link ash particle geometry with composition.&lt;/p&gt;&lt;p&gt;Initial results confirming the angular (3D-fragmented) nature of PM&lt;sub&gt;10 &lt;/sub&gt;and smaller particles from the La Palma eruption, suggest an ability to adhere to cells. Experiments to confirm this by exposing A549 human adenocarcinomic epithelial cells to La Palma ash particles are ongoing.&lt;/p&gt;