The Effect of Respirator Wear on Blood Lactate During Maximal Exertion

The impact of a filtering half-face respirator and a half-face supplied air respirator use on blood lactate production was assessed during maximal exertion to determine if anaerobic strain increased compared to no respirator use. Twenty-eight participants performed a 30 second cycling Wingate anaerobic test (WAnT) wearing a half-face respirator. Blood lactate production was measured to evaluate if there was an increase in anaerobic strain from wearing a tight fitting half-face respirator compared to wearing no respirator. A supplied air respirator WAnT was then performed using 18 participants from the first experiment to evaluate if supplied air decreased anaerobic strain. Data from both experiments were compared to evaluate differences in the physiological effects due to respirator use during maximal exertion. A survey was administered following the second WAnT experiment to measure the participants' perception of acceptability and impact of supplied air respirator use in workplace. The blood lactate levels measured directly after the WAnT yielded lower overall mean values during the half-mask respirator trial (12.1 mmollL) and supplied air respirator trial (12.2 mmollL) than the no respirator trial (13.1 mmoI/L). However, differences in blood lactate levels were not statistically significant (p =0.597). Participants reported an average acceptability of 92.3% to wearing the supplied air respirator while performing light work. However, the average acceptability decreased as the exertion increased to moderate (78.8%) and heavy (46.6%) workloads. The supplied air respirator used provided no significant reduction in anaerobic strain within this study group compared to either the filtering half-face respirator or the no respirator condition. However, there were differences in physiological effects of respirators on each gender identified in this study. Further assessment of the anaerobic impact of respirators on each gender should be conducted.

Patterned-ground plant communities along a bioclimate gradient in the High Arctic, Canada

Non-sorted circles, non-sorted polygons, and earth hummocks are common ground-surface features ill arctic regions. The), are caused by a variety of physical processes that Occur in permafrost regions including contraction cracking and frost heave. Here we describe the vegetation of patterned-ground forms on zonal sites at three location!: along an N-S transect through the High Arctic of Canada. We made 75 releves on patterned-ground features (circles, polygons, earth hummocks) and adjacent tundra (Interpolygon, intercircle, interhummock areas) and identified and classified the vegetation according to the Braun-Blanquet Method. Environmental factors were correlated with the vegetation data using a nonmetric multidimensional scaling ordination (NMDS). We identified eleven commnunities: (1) Puccinellia angustata-Papaver radicalum community in xeromesic non-sorted polygons of subzone A of the Circumpolar Arctic Vegetation Map; (2) Saxifraga-Parmelia omphalodes ssp. glacialis community in hydromesic interpolygon areas of subzone A; (3) Hypogymnia subobscura-Lecanora epibryon community In xeromesic non-sorted polygons of subzone B; (4) Orthotrichum speciosum-Salix arctica community In xeromesic interpolygon areas of subzone B; (5) Cochlearia groenlandica-Luzula nivalis community in hydromesic earth Mocks Of subzone B; (6) Salix arctica-Eriophorum angustifolium ssp. triste community in hygric earth hummocks of subzone 13; (7) Puccinellia angustata-Potentilla vahliana community in xeromesic non-sorted circles and bare patches of subzone Q (8) Dryas integrifolia-Carex rupestris community in xeromesic intercircle areas and vegetated patches of subzone C; (9) Braya glabella ssp. purpurascens-Dryas integrifolia community In hydromesic non-sorted circles of subzone Q (10) Dryas integrifolia-Carex aquatilis community in hydromesic intercircle areas of subzone C; and (11) Eriophorum angustifolium ssp. triste-Carex aquatilis community ill hygric intercircle areas of subzone C. The NMDS ordination displayed the vegetation types with respect to complex environmental gradients. The first axis of the ordination corresponds to a complex soil moisture gradient and the second axis corresponds to a complex geology/elevation/climate gradient. The tundra plots have a greater moss and graminoid cover than the adjacent frost-heave communities. In general, frost-heave features have greater thaw depths, more bare ground, thinner organic horizons, and lower soil moisture than the surrounding tundra. The morphology of the investigated patterned ground forms changes along the climatic gradient, with non-sorted pollygons dominating in the northernmost sites and non-sorted circles dominating, in the southern sites.