Educational Environments and Children\u27s Physical Activity and Sedentary Behaviors

Children and adolescents spend the majority of their day engaged in sedentary behaviors (SB), while also not meeting physical activity (PA) recommendations. The failure to develop and maintain health enhancing behaviors from a young age may impact an individual throughout their life. With children and adolescents spending a large proportion of their waking hours in a school setting, the educational environment presents an opportunity in which children and adolescents’ PA and SB can be positively influenced. Therefore, the purpose of this dissertation was to explore how children and adolescent’s school time PA and SB are associated with the educational setting, and how these behaviors change over the course of the school year and in response to non-traditional classroom settings. To address this purpose, three individual studies were completed. Study 1: Comparison of measures of elementary student’s classroom postural behaviors using direct observation and accelerometry in a school setting. The results of our research are only as good as the measures used, therefore to begin this series of studies two commonly used objective methods to assess children’s PA and SB were compared. Specifically, the inclinometer function of a hip-worn Actigraph GT3X+ accelerometer (ACC) and direct-observation (DO) were evaluated in their measurement of child and adolescent posture within a classroom environment that included stand-biased and traditional seated desks. Our results suggest that the measurement of both sitting and standing while in either a stand-biased or traditional seated desk were significantly different between DO and ACC, with DO consistently recording a higher proportion of time spent sitting, and a lower proportion of time standing regardless of desk assignment. The difference between DO and ACC measures of sitting (-18.9%; p=0.041) were significantly smaller when students used a stand-biased compared to a traditional seated desk. There was no significant difference between DO and ACC measures of standing between desk types, and lower limb fidgeting was found to have no main or interaction effect between desk type and differences of postural measures. It is important to remain cognizant of the methodologies used to assess youth behaviors, and the influence these measurement techniques can have on intervention outcomes involving environmental and other behavioral modifications. Study 2: An exploration into the variation of children’s in-school physical activity across the school year. Study two explored the variation in children and adolescents PA behaviors during active periods of the school day across the school year. Participating students completed a survey on five separate occasions throughout the school year, assessing activity levels during active transportation to and from school, at recess, and in physical education class. Our results suggest that overall, the weekly minutes that children and adolescents spent engaging in moderate- to vigorous-intensity PA (MVPA) remained relatively stable during recess (Avg: 42.2±12.2 minutes/week) and physical education class (Avg: 17.7±5.6 minutes/week) throughout the year. Statistically significant differences were found in the estimated weekly minutes of MVPA accumulated during active transportation to- and from-school, with the greatest accumulation occurring in September (To-School: 15.3±5.7 minutes/week; From-School: 32.0±10.5 minutes/week), and the lowest accumulation of MVPA to-school and from-school occurring in December (13.9±6.5 minutes/week; p=0.01) and March (28.5±11.9 minutes/week; p\u3c0.001), respectively. During active transportation to-school, weekly MVPA was highest in September (Fall; 15.3±5.7 minutes/week), and lowest in December (Winter; 13.9±6.5 minutes/week; p=0.01), while significant differences in active transportation from-school occurred between September (Fall; 32.0±10.5 minutes/week), December (Winter; 29.6±11.6 minutes/week; p=0.003), March (Spring; 28.5±11.9 minutes/week; p\u3c0.001), and April (Spring; 29.2±12.0 minutes/week; p\u3c0.001). Opportunities for PA throughout the school day may have been insufficient to aid youth in meeting recommendations, however the weekly opportunities which students are provided to engage in MVPA do not vary meaningfully throughout the year. To address this, school administrators may consider increasing the frequency and length of time which students are provided to engage in PA throughout the school day, such as during recess and physical education class, or by seeking to increase participation during periods of the school day where students are less consistently active throughout the school year, including during active transportation to- and from-school. Study 3: Comparison of children’s physical activity and sedentary behaviors between a nature-based and traditional educational setting. The third and final study of this dissertation aimed to compare within-child differences in PA and SB of a sample of children attending a single Pre-Kindergarten (Pre-K) educational program which alternated school days between a traditional and nature-based school setting. Overall, the results from this study suggest that children spent a significantly greater proportion of school time engaging in MVPA (+2.4±3.4%; p=0.002) while in a nature-based compared to a traditional Pre-K setting. Moreover, differences in MVPA between a nature-based and traditional program setting were most pronounced during the winter (~6 min/day), particularly while engaging in unstructured free play (~5 min/day). While the winter season has been shown to be a time when youth PA levels are at their lowest, the PA levels of children while in a nature-based setting remained constant from winter to spring. Therefore, modifying educational practices to increase opportunities for structured and unstructured activities outdoors, particularly during periods of the year when children are least active, may have the potential to positively influence children’s in-school PA and SB. Overall Conclusion. Together, these dissertation findings contribute toward a better understanding of the potential that the school setting has to provide meaningful and consistent opportunities for youth to engage in more active behaviors throughout the school day. The methodological approach of Study 1 highlights the differences in the measurement and interpretation of youth activity behaviors encountered when the methods of assessment vary, particularly as schools may seek to modify educational environments and promote more active behaviors. Study 2 provided insight into times of the school day and periods throughout the school year in which opportunities for children and adolescents to engage in PA can be enhanced, and Study 3 reinforces the relationship between time outside and children’s PA levels, providing one avenue for traditional school programs to incorporate more activity into the school day. Overall, the results of these studies provide school administrators and decision makers with important information surrounding school-related factors which are associated with children and adolescents PA and SB, and inform improvements in opportunities for the accumulation of school time PA. Ultimately, this dissertation contributes towards a body of research seeking to increase the quantity and quality of activity behaviors youth engage in, and to aid in the development of the healthy habits that children and adolescents practice throughout their lifespan

Principal component analysis of summertime ground site measurements in the Athabasca oil sands with a focus on analytically unresolved intermediate-volatility organic compounds

In this paper, measurements of air pollutants made at a ground site near Fort McKay in the Athabasca oil sands region as part of a multi-platform campaign in the summer of 2013 are presented. The observations included measurements of selected volatile organic compounds (VOCs) by a gas chromatograph–ion trap mass spectrometer (GC-ITMS). This instrument observed a large, analytically unresolved hydrocarbon peak (with a retention index between 1100 and 1700) associated with intermediate-volatility organic compounds (IVOCs). However, the activities or processes that contribute to the release of these IVOCs in the oil sands region remain unclear. Principal component analysis (PCA) with varimax rotation was applied to elucidate major source types impacting the sampling site in the summer of 2013. The analysis included 28 variables, including concentrations of total odd nitrogen (NOy), carbon dioxide (CO2), methane (CH4), ammonia (NH3), carbon monoxide (CO), sulfur dioxide (SO2), total reduced-sulfur compounds (TRSs), speciated monoterpenes (including α- and β-pinene and limonene), particle volume calculated from measured size distributions of particles less than 10 and 1&thinsp;µm in diameter (PM10−1 and PM1), particle-surface-bound polycyclic aromatic hydrocarbons (pPAHs), and aerosol mass spectrometer composition measurements, including refractory black carbon (rBC) and organic aerosol components. The PCA was complemented by bivariate polar plots showing the joint wind speed and direction dependence of air pollutant concentrations to illustrate the spatial distribution of sources in the area. Using the 95&thinsp;% cumulative percentage of variance criterion, 10 components were identified and categorized by source type. These included emissions by wet tailing ponds, vegetation, open pit mining operations, upgrader facilities, and surface dust. Three components correlated with IVOCs, with the largest associated with surface mining and likely caused by the unearthing and processing of raw bitumen.</p

Tau Ori and Tau Lib: Two New Massive Heartbeat Binaries

We report the discovery of two massive eccentric systems with BRITE data, tau Ori and tau Lib, showing heartbeat effects close to the periastron passage. τ Lib exhibits shallow eclipses that will soon vanish due to the apsidal motion in the system. In neither system, tidally excited oscillations were detected

Attentiveness and Fidgeting While Using a Stand-Biased Desk in Elementary School Children

Standing desks are a viable option to decrease sedentary time in the classroom. However, it is important that standing desks are not detrimental to classroom behavior or learning. The purpose of this study was to evaluate the impact of stand-biased desks on fidgeting and attentiveness. Ninety-seven students in grades 3, 4, and 6 (ages 8&ndash;12 years) volunteered to participate in this study. The intervention employed a within-classroom crossover design, with teacher-determined allocation for seating within each classroom and included the replacement of one-half of the traditional sitting desks with stand-biased desks. Direct observation of student&rsquo;s attentive and fidgeting behaviors occurred at three assessment periods, at baseline when all students were in a sitting desk condition and at the end of each nine-week intervention. Stand-biased desks did not influence fidgeting behavior, but did have an impact on attentive behavior. Students that were less attentive at baseline had a 40&ndash;80% increase incidence rate in non-attentive behavior while in the traditional desk as compared to the stand-biased desk after the intervention. While fidgeting and non-attentive episodes (p = 0.034) were significantly related, the type of desk did not significantly moderate this relationship (p = 0.810). Standing desks can be incorporated into the classroom without negatively influencing classroom behavior

Do Stand-Biased Desks in the Classroom Change School-Time Activity and Sedentary Behavior?

The purpose of this study was to determine the effect of stand-biased desks on the physical activity and sedentary behavior of third, fourth and sixth grade students across the school year. Methods: This within classroom crossover design study used teacher-determined allocation for seating within each classroom. Half of the students used a stand-biased desk and half used a sitting desk. Five-day hip-worn accelerometer assessments were completed at baseline and at the end of each nine-week intervention period. A mixed effects model was used to determine the differences in the percentage of time spent active and sedentary. Results: A total of 22, 36 and 41 students in 3rd, 4th and 6th grades, respectively, completed this study (57.1% male, 79.3% White). Regardless of the desk type, students became more sedentary (p &lt; 0.001) and less active (p &lt; 0.001) in the classroom as the school year progressed. After controlling for baseline activity, there was a significant interaction between the type of desk and time (p = 0.029). Students who spent a higher percentage of their classroom time sedentary engaged in less sedentary behavior when using a stand-biased desk compared to the traditional desk. Conclusion: The standing desk intervention was effective in mitigating the increase in sedentary behavior for those who started the school year more sedentary

Low levels of nitryl chloride at ground level: nocturnal nitrogen oxides in the Lower Fraser Valley of British Columbia

The nocturnal nitrogen oxides, which include the nitrate radical (NO3), dinitrogen pentoxide (N2O5), and its uptake product on chloride containing aerosol, nitryl chloride (ClNO2), can have profound impacts on the lifetime of NOx ( =  NO + NO2), radical budgets, and next-day photochemical ozone (O3) production, yet their abundances and chemistry are only sparsely constrained by ambient air measurements.Here, we present a measurement data set collected at a routine monitoring site near the Abbotsford International Airport (YXX) located approximately 30 km from the Pacific Ocean in the Lower Fraser Valley (LFV) on the west coast of British Columbia. Measurements were made from 20 July to 4 August 2012 and included mixing ratios of ClNO2, N2O5, NO, NO2, total odd nitrogen (NOy), O3, photolysis frequencies, and size distribution and composition of non-refractory submicron aerosol (PM1).At night, O3 was rapidly and often completely removed by dry deposition and by titration with NO of anthropogenic origin and unsaturated biogenic hydrocarbons in a shallow nocturnal inversion surface layer. The low nocturnal O3 mixing ratios and presence of strong chemical sinks for NO3 limited the extent of nocturnal nitrogen oxide chemistry at ground level. Consequently, mixing ratios of N2O5 and ClNO2 were low ( &lt;  30 and  &lt;  100 parts-per-trillion by volume (pptv) and median nocturnal peak values of 7.8 and 7.9 pptv, respectively). Mixing ratios of ClNO2 frequently peaked 1–2 h after sunrise rationalized by more efficient formation of ClNO2 in the nocturnal residual layer aloft than at the surface and the breakup of the nocturnal boundary layer structure in the morning. When quantifiable, production of ClNO2 from N2O5 was efficient and likely occurred predominantly on unquantified supermicron-sized or refractory sea-salt-derived aerosol. After sunrise, production of Cl radicals from photolysis of ClNO2 was negligible compared to production of OH from the reaction of O(1D) + H2O except for a short period after sunrise

Stable sulfur isotope measurements to trace the fate of SO2 in the Athabasca oil sands region

Concentrations and δ34S values for SO2 and size-segregated sulfate aerosols were determined for air monitoring station 13 (AMS 13) at Fort MacKay in the Athabasca oil sands region, northeastern Alberta, Canada as part of the Joint Canada-Alberta Implementation Plan for Oil Sands Monitoring (JOSM) campaign from 13 August to 5 September 2013. Sulfate aerosols and SO2 were collected on filters using a high-volume sampler, with 12 or 24ĝ€h time intervals. Sulfur dioxide (SO2) enriched in 34S was exhausted by a chemical ionization mass spectrometer (CIMS) operated at the measurement site and affected isotope samples for a portion of the sampling period. It was realized that this could be a useful tracer and samples collected were divided into two sets. The first set includes periods when the CIMS was not running (CIMS-OFF) and no 34SO2 was emitted. The second set is for periods when the CIMS was running (CIMS-ON) and 34SO2 was expected to affect SO2 and sulfate high-volume filter samples. δ34S values for sulfate aerosols with diameter D \u3e 0.49ĝ€μm during CIMS-OFF periods (no tracer 34SO2 present) indicate the sulfur isotope characteristics of secondary sulfate in the region. Such aerosols had δ34S values that were isotopically lighter (down to ĝ\u275.3ĝ€‰) than what was expected according to potential sulfur sources in the Athabasca oil sands region (+3.9 to +11.5ĝ€‰). Lighter δ34S values for larger aerosol size fractions are contrary to expectations for primary unrefined sulfur from untreated oil sands (+6.4ĝ€‰) mixed with secondary sulfate from SO2 oxidation and accompanied by isotope fractionation in gas phase reactions with OH or the aqueous phase by H2O2 or O3. Furthermore, analysis of 34S enhancements of sulfate and SO2 during CIMS-ON periods indicated rapid oxidation of SO2 from this local source at ground level on the surface of aerosols before reaching the high-volume sampler or on the collected aerosols on the filters in the high-volume sampler. Anti-correlations between δ34S values of dominantly secondary sulfate aerosols with D \u3c ĝ€†0.49ĝ€μm and the concentrations of Fe and Mn (rĝ€ Combining double low line ĝ€ĝ\u270.80 and rĝ€ Combining double low line ĝ€ĝ\u270.76, respectively) were observed, suggesting that SO2 was oxidized by a transition metal ion (TMI) catalyzed pathway involving O2 and Fe3+ and/or Mn2+, an oxidation pathway known to favor lighter sulfur isotopes. Correlations between SO2 to sulfate conversion ratio (F(s)) and the concentrations of α-pinene (rĝ€ Combining double low line ĝ€0.85), β-pinene (rĝ€ Combining double low line ĝ€0.87), and limonene (rĝ€ Combining double low line ĝ€0.82) during daytime suggests that SO2 oxidation by Criegee biradicals may be a potential oxidation pathway in the study region. © Author(s) 2018