The effectiveness of respiratory protection worn by communities to protect from volcanic ash inhalation. Part II: Total inward leakage tests

Inhalation of ash can be of great concern for affected communities, during and after volcanic eruptions. Governmental and humanitarian agencies recommend and distribute a variety of respiratory protection (RP), most commonly surgical masks. However, there is currently no evidence on how effective such masks are in protecting wearers from volcanic ash. In Part I of this study (Mueller et al., 2018), we assessed the filtration efficiency (FE) of 17 materials from different forms of RP against volcanic ash and a surrogate, low-toxicity dust, Aloxite. Based on those results, we now present the findings from a volunteer simulation study to test the effect of facial fit through assessment of Total Inward Leakage (TIL).Four different disposable RP types that demonstrated very high median FE (≥96% for Aloxite; ≥89% for volcanic ash) were tested without provision of training on fit. These were an industry-certified mask (N95-equiv.); a surgical mask from Japan designed to filter PM_2.5; a flat-fold basic mask from Indonesia; and a standard surgical mask from Mexico, which was also tested with an added medical bandage on top, as an additional intervention to improve fit.Ten volunteers (6 female, 4 male) were recruited. Each RP type was worn by volunteers under two different conditions simulating cleaning-up activities during/after volcanic ashfall. Each activity lasted 10?min and two repeats were completed for each RP type per activity. Dust (as PM_2.5) concentration inside and outside the mask was measured with two TSI SidePak aerosol monitors (Models AM510 and AM520, TSI, Minnesota, USA) to calculate TIL. A questionnaire was administered after each test to collect perceptions of fit, comfort, protection and breathability.The best-performing RP type, across both activities, was the industry-certified N95-equiv. mask with 9% mean TIL. The standard surgical mask and the basic flat-fold mask both performed worst (35% TIL). With the additional bandage intervention, the surgical mask mean TIL improved to 24%. The PM_2.5 surgical mask performed similarly, with 22% TIL. The N95-equiv. mask was perceived to provide the best protection, but was also perceived as being uncomfortable and more difficult to breathe through.This study provides a first objective evidence base for the effectiveness of a selection of RP types typically worn around the world during volcanic crises. The findings will help agencies to make informed decisions on the procurement and distribution of RP in future eruptions.     

Experimental effects of graft revascularization and consistency on cervicofacial fat transplant survival.

An experimental study evaluating the contributions of graft composition (particulate vs. whole) and revascularization (immediate reanastomosis vs. delayed) to cervicofacial fat transplantation was conducted in rats. Distant (inguinal fat) grafts were bilaterally transplanted to a muscular bed in the cervicofacial region as a free flap (anastomosis to carotid and jugular vessels) or as a free graft (either particulate or whole). Postoperative assessment was made by comparison of pre- and post-operative weights and histologic examination of all specimens, and by acrylic microangiography in select animals of each group. The fat flaps exhibited minimal loss of tissue volume, and showed a normal histologic appearance of the adipocytes and extensive vascular elements within the grafts. Conversely, considerable volume loss occurred in both the particulate and whole fat grafts. Histologically, the free graft was characterized by cellular disruption, atrophic adipocytes, and areas of acellularity. Whole grafts had histologic evidence of vessels located primarily at the periphery, whereas particulate grafts had increased intragraft vessels. Only the fat flaps showed observable intragraft vasculature by microangiography. These findings suggest that reduction of fat grafts into smaller components, eg, by liposuction harvesting, does not improve graft survival or decrease posttransplant resorption.     

Chemiluminescence of neutrophils from patients with Beh?et's disease and its correlation with an increased proportion of uncommon serotypes of Streptococcus sanguis in the oral flora

Zymosan-induced chemiluminescence was investigated in whole blood and in neutrophils: in both, the peak count was frequently elevated in Beh?et's disease, and was significantly higher than in healthy controls; similarly the peak time was shorter. There were more uncommon serotypes of Streptococcus sanguis in the oral flora of patients with Beh?et's disease. Common serotypes were present in the flora of healthy controls, but not in patients with the disease. The percentage of Strep. sanguis in the oral flora was significantly correlated with the level of chemiluminescence response. Thus infection with uncommon serotypes of Strep. sanguis may play a role in the aetiology of Beh?et's disease.     

Oral mucosal status and major salivary gland function

Normal salivary function is considered to be critical for the maintenance of healthy oral mucosa. However, few studies have examined mucosal changes in patients with objectively documented salivary gland performance. In the present report, the mucosal status of 298 subjects being evaluated in a dry mouth clinic was assessed. A complete oral examination was performed and unstimulated and stimulated salivary samples were collected separately from the parotid and submandibular/sublingual glands. Data were analyzed according to diagnosis and salivary output after the assignment of an oral mucosal rating to each subject. In general, the mucosal surfaces were well preserved and infections were not seen. Patients evaluated for Sj?gren's syndrome and radiation-induced xerostomia had the lowest salivary gland performance but displayed a mucosal status similar to denture-wearing healthy subjects or patients with normal salivary flow who had idiopathic xerostomia. However, those patients with a total lack of salivary flow rarely had normal-appearing oral mucosa. These results confirm a role for saliva in oral mucosal preservation and also suggest that other factors may act to maintain oral mucosal integrity.