Housing characteristics and indoor air quality in households of Alaska Native children with chronic lung conditions.

Alaska Native children experience high rates of respiratory infections and conditions. Household crowding, indoor smoke, lack of piped water, and poverty have been associated with respiratory infections. We describe the baseline household characteristics of children with severe or chronic lung disease participating in a 2012-2015 indoor air study. We monitored indoor PM2.5, CO2 , relative humidity %, temperature, and VOCs and interviewed caregivers about children's respiratory symptoms. We evaluated the association between reported children's respiratory symptoms and indoor air quality indicators using multiple logistic regression analysis. Compared with general US households, study households were more likely overcrowded 73% (62%-82%) vs 3.2% (3.1%-3.3%); had higher woodstove use as primary heat source 16% (9%-25%) vs 2.1% (2.0%-2.2%); and higher proportion of children in a household with a smoker 49% (38%-60%) vs 26.2% (25.5%-26.8%). Median PM2.5 was 33 µg/m3 . Median CO2 was 1401 ppm. VOCs were detectable in all homes. VOCs, smoker, primary wood heat, and PM2.5>25 µg/m3 were associated with higher risk for cough between colds; VOCs were associated with higher risk for wheeze between colds and asthma diagnosis. High indoor air pollutant levels were associated with respiratory symptoms in household children, likely related to overcrowding, poor ventilation, woodstove use, and tobacco smoke.

Meta-analysis: abundance, behavior, and hydraulic energy shape biotic effects on sediment transport in streams.

An increasing number of studies have emphasized the need to bridge the disciplines of ecology and geomorphology. A large number of case studies show that organisms can affect erosion, but a comprehensive understanding of biological impacts on sediment transport conditions is still lacking. We use meta-analysis to synthesize published data to quantify the effects of the abundance, body size, and behavior of organisms on erosion in streams. We also explore the influence of current velocity, discharge, and sediment grain size on the strength of biotic effects on erosion. We found that species that both increase erosion (destabilizers) and decrease erosion (stabilizers) can alter incipient sediment motion, sediment suspension, and sediment deposition above control conditions in which the organisms were not present. When abundance was directly manipulated, these biotic effects were consistently stronger in the higher abundance treatment, increasing effect sizes by 66%. Per capita effect size and per capita biomass were also consistently positively correlated. Fish and crustaceans were the most studied organisms, but aquatic insects increased the effect size by 550 x compared to other types of organisms after accounting for biomass. In streams with lower discharge and smaller grain sizes, we consistently found stronger biotic effects. Taken collectively, these findings provide synthetic evidence that biology can affect physical processes in streams, and these effects can be mediated by hydraulic energy. We suggest that future studies focus on understudied organisms, such as biofilms, conducting experiments under realistic field conditions, and developing hypotheses for the effect of biology on erosion and velocity currents in the context of restoration to better understand the forces that mediate physical disturbances in stream ecosystems.

The effect of fluid replacement on endurance performance.

The purpose of this study was to examine the effects of fluid replacement on power output (PO), rating of perceived exertion (RPE), heart rate (HR), body weight (BW), urine osmolarity (Uosm), and urine electrolyte concentrations ([UNa+], [UK+], [UCl-]) in physically active men (n = 4) and women (n = 7). The participants were asked to generate their highest possible PO during 60 minutes of cycling under 3 randomized conditions: ingestion of (a) no fluid (trial 1); (b) 1200 ml of distilled water (trial 2); and (c) 1,200 ml of Gatorade (trial 3). BW and urine volume (Vu) were measured before and after the ride to determine sweat rate [(SR = deltaBW + Vfluid intake + Vu)/time]. The results indicated that there were no significant differences between trials for PO (123-127 W), RPE (14), HR (140-142 b x min(-1)), and SR (11.9-12.4 ml x min(-1)). However, [UNa+] was significantly (p < 0.05) lower postexercise for all 3 trials, and [UCl-] was significantly reduced following trials 2 and 3. There was a significant increase (p < 0.001) in BW postexercise for trials 2 and 3 when compared with the no-fluid trial; however, the effects of water and Gatorade were similar. These results suggest that fluid replacement during 1 hour of moderately intense cycling does not enhance performance in physically active men and women who are normally hydrated.