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Bamboo, a fast-growing giant grass, typically begins yielding within three to four years of planting. Despite Ethiopia's abundant bamboo resources, many suitable dryland areas remain uncultivated, particularly in the eastern lowlands. This study, conducted from 2011 to 2014 at the Dire Dawa plantation site, evaluated the adaptation and growth performance of lowland bamboo (Oxytenanthera abyssinica) and identifies effective management practices for this region. A total of 162 bamboo seedlings were cultivated using three soil mix types: Treatment 1 (T1) with a 3:2:1 ratio of local soil, animal manure, and sand; Treatment 2 (T2) with a 3:2 ratio of local soil and animal manure (without sand); and Treatment 3 (T3) with a 6:2 ratio of local soil and animal manure (without sand). After four months in the nursery, seedlings were selected based on growth performance and transplanted with (W1) and without mulch (WO). The experiment followed a factorial Randomized Complete Block Design (RCBD) with three replications. Data collected at 6, 12, 18, and 24 months were analyzed using SPSS software. There were no significant differences in survival and adaptability across soil mix types and mulching treatments, although variations in growth were observed. T2 demonstrated superior performance in shoot emergence, culm height and root collar diameter, while T3 exhibited the lowest growth. Based on these findings, the 3:2 soil mix is recommended for optimal bamboo growth in Dire Dawa and similar agro-ecologies, with consistent watering during the first three months post-plantation to ensure successful establishment.

Bamboos are naturally fast-growing species in tropical and non-tropical regions, with some species growing more than 1 m per day. Oxytenanthera abyssinica is an important bamboo species that could help meet current and future needs worldwide. This study was designed to assess the effects of harvesting techniques and intensities on sustainable utilization of O. abyssinica. Clumps that had a similar number culms were used to conduct the experiment. A factorial experiment with two harvesting techniques (X-shape and Horse-shoe shape) and five levels of harvesting intensities (25, 50, 75, 100 and 0 % harvesting of mature culms) was conducted for five successive years in the dry season. Sprouted and dead shoots, recruited culms, and mean culm diameter at breast height were recorded. Data were analysed using two-way-ANOVA. Culm/shoot sprouting had significantly different values with harvesting techniques; the X-shape harvesting technique produced a higher number culms than horse-shoe harvesting technique. Interaction effects between harvesting techniques and harvesting intensities on shoot sprouting, culm recruitment and shoot abortion were not observed. Both harvesting techniques and intensities had a significant effect on mean culm diameter; i.e., 25 % and 75 % of the mature culms harvested under the X-shape and horse-shoe harvesting techniques, respectively, produced thicker bamboo culms than the unharvested clump (control). Culm recruitment decreased in the second year, and then increased in the third year, subsequently showed a decreasing trend for all treatments. This may have been related to repeated culm harvesting. The population structure has also varied with harvesting technique and intensity. To utilize this species sustainably, the species may need a specific cutting cycle. This study suggests the need for further study through incorporating cutting cycles with different levels of harvesting intensity to develop a sustainable management method.

Highland bamboo (Oldeania alpina) (K. Schum.) Stapleton (syn: Yushania alpina), is a naturally distributed and cultivated species in the south, south-west, central and north-western highlands of Ethiopia. This study aimed to assess and describe bamboo landraces in Ethiopia based on their dendrometric and morphological traits, and also to understand their potential uses in a local context and identify and recommend potential landraces for wider industrial application. It was carried out in potential highland bamboo growing areas of four regional states of Ethiopia, viz., Amhara, Oromia, Sidama, and Southern Nations, Nationalities and People’s Regions. An extensive field survey was conducted using “transect walk for direct observation” across bamboo stands to collect technical information on identifiable characteristics for ethno-taxonomy, potential household uses, and workability of the culms of the different highland bamboo landraces. The study revealed about 24 landraces with some distinct morphological differences and traditional uses. A cladistic method also exposed some hierarchical dissimilarity among clusters of highland bamboo landraces. In the principal component analysis, nodal area contributed the highest variability among the landraces. The study also found the existence of differences in the preference and utilization of different highland bamboo landraces for various products and purposes based on the properties of the landraces. Based on the preferences of knowledgeable local bamboo processors and quality features observed on the landraces in each of the specific sites, we conclude that landraces such as Lala, Lodo, Tsarzo, Hinkonokita, Sella, Midasho, Ganticha, Shimiti, Demamo, Tikuro and Agade be widely promoted in new areas in the highlands. This would enable wood-based industries to produce quality end products while maintaining the diversity of landraces in the landscape.

Highland bamboo (Oldeania alpina) is fast growing perennial plant that occurs as small holder plantation and naturally in the highlands of Ethiopia with a wide range of values and uses. This study assessed environmental conditions where the species grows, and related the sites-suitability information to other potential regions in Ethiopia. Field survey was conducted to Oldeania alpina growing areas in Ethiopia. Data were collected on dendrometric and environmental variables from field plots of 400 m2 of bamboo stands in three replications in each of the study districts in the regions. Consultations were also held with key informants, women, youth and elder focus group discussants on the common uses and production constraints of the species. The study identified wider uses of the species from being raw material for household utensils, furniture, fencing to building local houses in Ethiopia. Observations indicate that Oldeania alpina grows in the south, south-western, central and north-western highlands of Ethiopia at altitudes ranging from 2200 to 4000 m.a.s.l. It grows rapidly, where after planting from offset, starts to yield useable culm within three to four years. The species growing sites characteristics in the present study indicated that it’s well performing in the altitudinal range between 2387 and 2979 m.a.s.l. We recommend promoting highland bamboo in Ethiopia for better culm yield on sites with elevation from 2300 up to 3500 m.a.s.l with mean annual rainfall >1200 mm, temperature varying from min. 6 °C to max. 30 °C and slope from 0 to 60% to attain optimum growth across the country.

Gestational air pollution exposure was associated with childhood obesity. However, little is known about the effect of air pollution exposure during the preconception period, a critical window when environmental exposures may affect body growth trajectory and increase obesity risk. We conducted a population-based prospective cohort study of preconception women and their newborn children followed until 2 years old from metropolitan Shanghai, China to investigate the impact of preconception air pollution on childhood weight and body mass index (BMI) growth trajectories. Exposures to PM 2.5 , PM 10 , and NO 2 during 3 months before conception and each trimester of pregnancy were estimated using high-resolution spatiotemporal models matched at residential addresses. Children's weight and BMI were assessed postnatally every three months. Multivariate and longitudinal models with piecewise linear mixed effects were used to examine the relationship between preconception air pollution and child growth trajectories of weight, BMI, and standardized BMI (BMIZ). The study population comprised 26,714 women in the baseline enrolled in preconception clinics and 5,834 children reached 2 years included in the analysis with 34,398 longitudinal weight and height measurements. One interquartile range (IQR) increase in preconception PM 2.5 (16.2 μg/m 3 ) was associated with a 0.078 (95% confidence interval (CI): 0.002-0.154, p = 0.04) increase in attained BMIZ and 1 IQR increase of PM 10 (21.1 μg/m 3 ) were associated with an 0.093 (95% CI: 0.002-0.184, p = 0.04) kg/m 2 increase in attained BMI, respectively, at the age of two years, after controlling for individual covariates and gestational air pollution exposure. Higher weight, BMI, and BMIZ growth rates during 6-24 months of life were also associated with higher preconception NO 2 and PM exposure. Males and children born to mothers less than 35 years old or with overweight/obesity status were more affected by preconception air pollution exposure on weight growth. The 3-month preconception period was a critical time window for air pollution exposure., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Recent studies have linked air pollution to increased risk for behavioral problems during development, albeit with inconsistent findings. Additional longitudinal studies are needed that consider how emotional behaviors may be affected when exposure coincides with the transition to adolescence - a vulnerable time for developing mental health difficulties. This study investigates if annual average PM 2.5 and NO 2 exposure at ages 9-10 years moderates age-related changes in internalizing and externalizing behaviors over a 2-year follow-up period in a large, nationwide U.S. sample of participants from the Adolescent Brain Cognitive Development (ABCD) Study®. Air pollution exposure was estimated based on the residential address of each participant using an ensemble-based modeling approach. Caregivers answered questions from the Child Behavior Checklist (CBCL) at the baseline, 1-year follow-up, and 2-year follow-up visits, for a total of 3 waves of data; from the CBCL we obtained scores on internalizing and externalizing problems plus 5 syndrome scales (anxious/depressed, withdrawn/depressed, rule-breaking behavior, aggressive behavior, and attention problems). Zero-inflated negative binomial models were used to examine both the main effect of age as well as the interaction of age with each pollutant on behavior while adjusting for various socioeconomic and demographic characteristics. Against our hypothesis, there was no evidence that greater air pollution exposure was related to more behavioral problems with age over time., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Background: Exposure to lipophilic persistent organic pollutants (POPs) is ubiquitous. POPs are metabolic disrupting chemicals and are potentially diabetogenic., Methods: Using a multi-cohort study including overweight adolescents from the Study of Latino Adolescents at Risk (SOLAR, N = 301, 2001-2012) and young adults from the Southern California Children's Health Study (CHS, N = 135, 2014-2018), we examined associations of POPs and risk factors for type 2 diabetes. SOLAR participants underwent annual visits for a median of 2.2 years and CHS participants performed a single visit, during which a 2-h oral glucose tolerance test was performed. Linear mixed models were used to examine associations between plasma concentrations of POPs [4,4'-dichlorodiphenyldichloroethylene (4,4'-DDE), hexachlorobenzene (HCB), PCBs-153, 138, 118, 180 and PBDEs-154, 153, 100, 85, 47] and changes in glucose homeostasis across age and pubertal stage., Results: In SOLAR, exposure to HCB, PCB-118, and PBDE-153 was associated with dysregulated glucose metabolism. For example, each two-fold increase in HCB was associated with approximately 2 mg/dL higher glucose concentrations at 30 min (p = 0.001), 45 min (p = 0.0006), and 60 min (p = 0.03) post glucose challenge. Compared to individuals with low levels of PCB-118, individuals with high levels exhibited a 4.7 mg/dL (p = 0.02) higher glucose concentration at 15 min and a 3.6 mg/dL (p = 0.01) higher glucose concentration at 30 min. The effects observed with exposure to organochlorine compounds were independent of pubertal stages. PBDE-153 was associated with the development of dysregulated glucose metabolism beginning in late puberty. At Tanner stage 4, exposure to PBDE-153 was associated with a 12.7 mg/dL higher 60-min glucose concentration (p = 0.009) and a 16.1 mg*dl -1 *hr -1 higher glucose AUC (p = 0.01). These associations persisted at Tanner 5. In CHS, PBDE-153 and total PBDE were associated with similar increases in glucose concentrations., Conclusion: Our results suggest that childhood exposure to lipophilic POPs is associated with dysregulated glucose metabolism., (Copyright © 2022 Elsevier Inc. All rights reserved.)

Prenatal arsenic exposure has been associated with reduced fetal growth and increased risk for preterm birth, but most studies have been conducted in highly exposed populations outside the U.S. or in non-Hispanic populations in the rural U.S. The objectives of the current study were to: 1) examine the impact of early pregnancy exposure to arsenic on birth weight and gestational age at birth in a predominately lower income Hispanic pregnancy cohort in urban Los Angeles and 2) compare multiple biomarkers of arsenic exposure (blood, urine, and hair) assessed in early pregnancy (mean ± SD gestational age at biospecimen collection: 14 ± 4 weeks). Total arsenic (blood, hair) was measured by ICP-MS and speciated arsenic (urine) was measured by HPLC coupled to ICP-MS. Associations between log 2 -transformed arsenic measures and birth outcomes were evaluated using multivariable linear regression. A doubling in hair arsenic was associated with a 72.2 g (95% CI: -144.3, -0.1, P = 0.05) lower birth weight, after adjusting for potential confounders and gestational age at birth. A similar but non-significant trend was observed for blood arsenic, but not urine arsenic. The inverse association between hair arsenic and birth weight was more pronounced among infants whose mothers gained greater amounts of weight during pregnancy (P interaction  = 0.02). The association between urinary monomethyl arsenic and GA at birth differed by pre-pregnancy BMI (P interaction <0.01). This study provides evidence that even at relatively low levels of exposure, arsenic exposure (measured in hair samples collected in early pregnancy) may adversely affect fetal growth in this understudied population, particularly in combination with greater gestational weight gain. Future studies with larger sample sizes are needed to confirm these findings and to further investigate some of the inconsistencies observed for the different arsenic biomarkers evaluated., Competing Interests: Declaration of competing interest CGH, SFF, EG, TJ, RI, KB, TAC, TLH, BHG, DRS, TMB, and CVB declare no conflicts of interest. WEF is a founding partner in EnMed MicroAnalytics, a company that provides heavy metal screening for newborns and children., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Background: Previous youth tobacco research has identified multiple correlated risk factors for initiation of cigarette and e-cigarette use; whether these factors are independently associated with initiation is not known, due to challenges with disentangling the independent effects of these correlated risk factors., Methods: Students in 11 th /12 th grade enrolled in the Southern California Children's Health Study were surveyed in 2014 (baseline) and again in 2015 (N = 1553). Structural equation models (SEM) were developed to investigate associations of susceptibility, marketing, and the social environment (as latent factors), and other tobacco use at baseline with cigarette or e-cigarette initiation between baseline and follow-up. Analyses were restricted to baseline never cigarette users (N = 1293) for models evaluating cigarette initiation, and to never e-cigarette users (N = 1197) for models evaluating e-cigarette initiation., Results: In fully-adjusted prospective SEM models, latent factors for cigarette susceptibility, marketing, and the social environment, along with ever e-cigarette use and ever hookah use at baseline were independently associated with cigarette initiation between baseline and follow-up (P < 0.05). Similarly, latent factors for e-cigarette susceptibility, marketing, and the social environment, along with ever hookah use at baseline were associated with e-cigarette initiation between baseline and follow-up (P < 0.05); however, cigarette use at baseline was not associated with e-cigarette initiation in SEM models (P = 0.16)., Conclusions: We identified independent effects of multiple risk factors in SEM models on initiation of cigarettes and e-cigarettes. E-cigarette use was associated with cigarette initiation, but cigarette use was not associated with e-cigarette initiation in fully adjusted models. Research to identify underlying causal mechanisms is warranted., (Copyright © 2019 Elsevier B.V. All rights reserved.)

Objective: Neighborhood greenspace improves mental health of urban-dwelling populations, but its putative neurobehavioral benefits in adolescents remain unclear. We conducted a prospective study on urban-dwelling adolescents to examine the association between greenspace in residential neighborhood and aggressive behaviors., Method: Participants (n = 1,287) of the Risk Factors for Antisocial Behavior Study, a multi-ethnic cohort of twins and triplets born in 1990 to 1995 and living in Southern California, were examined in 2000 to 2012 (aged 9-18 years) with repeated assessments of their aggressive behaviors by the parent-reported Child Behavior Checklist. Normalized Difference Vegetation Index (NDVI) derived from satellite imagery was used as a proxy for residential neighborhood greenspace aggregated over various spatiotemporal scales before each assessment. Multilevel mixed-effects models were used to estimate the effects of greenspace on aggressive behaviors, adjusting for within-family/within-individual correlations and other potential confounders., Results: Both short-term (1- to 6-month) and long-term (1- to 3-year) exposures to greenspace within 1,000 meters surrounding residences were associated with reduced aggressive behaviors. The benefit of increasing vegetation over the range (∼0.12 in NDVI) commonly seen in urban environments was equivalent to approximately 2 to 2.5 years of behavioral maturation. Sociodemographic factors (e.g., age, gender, race/ethnicity, and socioeconomic status) and neighborhood quality did not confound or modify these associations, and the benefits remained after accounting for temperature., Conclusion: Our novel findings support the benefits of neighborhood greenspace in reducing aggressive behaviors of urban-dwelling adolescents. Community-based interventions are needed to determine the efficacy of greenspace as a preemptive strategy to reduce aggressive behaviors in urban environments., (Copyright © 2016 American Academy of Child and Adolescent Psychiatry. Published by Elsevier Inc. All rights reserved.)

Purpose: One concern regarding the recent increase in adolescent e-cigarette use is the possibility that electronic (e-) cigarettes may be used by those who might not otherwise have used cigarettes, and that dual use, or transition to cigarette use alone, may follow., Methods: Questionnaire data were obtained in 2014 from 11th/12th grade students attending schools in 12 communities included in the Southern California Children's Health Study. We evaluated the cross-sectional association between e-cigarette use, the social environment (family and friends' use and approval of e-cigarettes and cigarettes), and susceptibility to future cigarette use among never cigarette smokers (N = 1,694), using previously validated measures based on reported absence of a definitive commitment not to smoke., Results: Among adolescents who had never used cigarettes, 31.8% of past e-cigarette users and 34.6% of current (past 30-day) e-cigarette users indicated susceptibility to cigarette use, compared with 21.0% of never e-cigarette users. The odds of indicating susceptibility to cigarette use were two times higher for current e-cigarette users compared with never users (odds ratio = 1.97; 95% confidence interval: 1.21-3.22). A social environment favorable to e-cigarettes (friends' use of and positive attitudes toward the use of e-cigarettes) was also associated with greater likelihood of susceptibility to cigarette use, independent of an individual's e-cigarette use., Conclusions: E-cigarette use in adolescence, and a pro-e-cigarette social environment, may put adolescents at risk for future use of cigarettes. E-cigarettes may contribute to subsequent cigarette use via nicotine addiction or social normalization of smoking behaviors., (Copyright © 2016 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.)

Purpose: There is a growing public health concern related to the rapid increase in the use of multiple tobacco products among adolescents. This study examined patterns of adolescent use of cigarettes, e-cigarettes, cigars/cigarillo, hookah/waterpipe, and smokeless/dip/chewing tobacco in a population of southern California adolescents., Methods: Data from 2,097 11th- and 12th-grade participants in the Southern California Children's Health Study were collected via self-report in 2014. Study participants were asked about lifetime and current (past 30 days) use of cigarettes, cigars/cigarillos/little cigars, e-cigarettes, hookah/waterpipe, and smokeless/dip/chewing tobacco. Latent class analysis (LCA) was used to identify patterns of tobacco use., Results: Hookah/waterpipe tobacco use had the highest current prevalence (10.7%) followed by e-cigarettes (9.6%). The prevalence of use of smokeless/dip/chewing tobacco was lowest, with 2.2% of adolescents reporting current use. The LCA suggested four distinct classes, comprising nonusers (72.3% of the sample), polytobacco experimenters (13.9%), e-cigarette/hookah users (8.2%), and polytobacco users (5.6%). Multinomial logistic regression based on these four classes found that males had double the odds to be polytobacco users relative to nonusers compared to females (odds ratio, 2.3; 95% confidence interval, 1.26-4.25)., Conclusions: By identifying naturally occurring configurations of tobacco product use in teens, these findings may be useful to practitioners and policymakers to identify the need for tobacco control interventions that address specific tobacco products and particular combinations of polytobacco use. LCA can be used to identify segments of the population overrepresented among certain tobacco use classes (e.g., boys) that may benefit most from targeted polyproduct intervention approaches., (Copyright © 2016 Society for Adolescent Health and Medicine. Published by Elsevier Inc. All rights reserved.)

Few studies have simultaneously evaluated multiple levels of influence on whether children walk to school. A large cohort of 4338 subjects from 10 communities was used to identify the determinants of walking through (1) a one-level logistic regression model for individual-level variables and (2) a two-level mixed regression model for individual and school-level variables. Walking rates were positively associated with home-to-school proximity, greater age, and living in neighborhoods characterized by lower traffic density. Greater land use mix around the home was, however, associated with lower rates of walking. Rates of walking to school were also higher amongst recipients of the Free and Reduced Price Meals Program and attendees of schools with higher percentage of English language learners. Designing schools in the same neighborhood as residential districts should be an essential urban planning strategy to reduce walking distance to school. Policy interventions are needed to encourage children from higher socioeconomic status families to participate in active travel to school and to develop walking infrastructures and other measures that protect disadvantaged children., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Objective: Racial/ethnic differences in common carotid artery intima-media thickness (CIMT) and in risk factors associated with CIMT have been predominantly observed in middle-aged and older individuals. We aimed to characterize racial/ethnic differences CIMT and other cardiovascular risk factors in a healthy, young-adult population., Methods: College students were recruited as part of a study to characterize determinants of atherogenesis. Students were eligible if they were lifetime non-smokers, lived in the United States since six months of age, and attended high school in the United States. Blood pressure, heart rate, height, and weight were measured, B-mode carotid ultrasound was performed, questionnaires were administered and a 12-h fasting blood sample was collected. Associations between CIMT and other variables were assessed in 768 students aged 18-25 years using linear regression analysis., Results: In models adjusted for common cardiovascular risk factors, sex exhibited the strongest influence on CIMT, with men having 15.4 μm larger CIMT compared to women (95%CI 6.6, 24.2). Race/ethnicity was also strongly associated with CIMT. African Americans had 17.3 μm greater CIMT (95%CI -0.3, 34.8) compared to non Hispanic Whites, whereas Asians and Hispanic Whites had 14.3 (95%CI -24.3, -4.4) and 15.4 (95%CI -26.2, -4.7) μm smaller CIMT, respectively. BMI and systolic blood pressure were positively associated with CIMT., Conclusion: The risk factors associated with atherogenesis later in life are already present and observable in college-aged young adults, so targeted campaigns to reduce life-long cardiovascular disease burden should be initiated earlier in life to improve public health., (Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.)

The objective of the research was to assess how proximity to parks and recreational resources affects the development of childhood obesity through a longitudinal study. Data were collected on 3173 children aged 9-10 from 12 communities in Southern California in 1993 and 1996. Children were followed for eight years to collect longitudinal information, including objectively measured body mass index (BMI). Multilevel growth curve models were used to assess associations between attained BMI growth at age 18 and numerous environmental variables, including park space and recreational program access. For park acres within a 500 m distance of children's homes, there were significant inverse associations with attained BMI at age 18. Effect sizes were larger for boys than for girls. Recreation programs within a 10 km buffer of children's homes were significantly and inversely associated with achieved levels in BMI at age 18, with effect sizes for boys also larger than those for girls. We conclude that children with better access to parks and recreational resources are less likely to experience significant increases in attained BMI., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Background: Whether local exposure to major roadways adversely affects lung-function growth during the period of rapid lung development that takes place between 10 and 18 years of age is unknown. This study investigated the association between residential exposure to traffic and 8-year lung-function growth., Methods: In this prospective study, 3677 children (mean age 10 years [SD 0.44]) participated from 12 southern California communities that represent a wide range in regional air quality. Children were followed up for 8 years, with yearly lung-function measurements recorded. For each child, we identified several indicators of residential exposure to traffic from large roads. Regression analysis was used to establish whether 8-year growth in lung function was associated with local traffic exposure, and whether local traffic effects were independent of regional air quality., Findings: Children who lived within 500 m of a freeway (motorway) had substantial deficits in 8-year growth of forced expiratory volume in 1 s (FEV(1), -81 mL, p=0.01 [95% CI -143 to -18]) and maximum midexpiratory flow rate (MMEF, -127 mL/s, p=0.03 [-243 to -11), compared with children who lived at least 1500 m from a freeway. Joint models showed that both local exposure to freeways and regional air pollution had detrimental, and independent, effects on lung-function growth. Pronounced deficits in attained lung function at age 18 years were recorded for those living within 500 m of a freeway, with mean percent-predicted 97.0% for FEV1 (p=0.013, relative to >1500 m [95% CI 94.6-99.4]) and 93.4% for MMEF (p=0.006 [95% CI 89.1-97.7])., Interpretation: Local exposure to traffic on a freeway has adverse effects on children's lung development, which are independent of regional air quality, and which could result in important deficits in attained lung function in later life.

Oxides of nitrogen in fresh traffic exhaust are known to scavenge ambient ozone. However, there has only been little study of local variation in ozone resulting from variation in vehicular traffic patterns within communities. Homes of 78 children were selected from a sample of participants in 3 communities in the southern California Children's Health Study. Twenty-four hour ozone measurements were made simultaneously at a home and at a community central site monitor on two occasions between February and November 1994. Homes were geo-coded, and local residential nitrogen oxides (NOx) above regional background due to nearby traffic at each participant's home were estimated using a line source dispersion model. Measured home ozone declined in a predictable manner as modeled residential NOx increased. NOx modeled from local traffic near homes accounted for variation in ozone concentrations of as much as 17 parts per billion. We conclude that residential ozone concentrations may be over- or underestimated by measurements at a community monitor, depending on the variation in local traffic in the community. These findings may have implications for studies of health effects of traffic-related pollutants.

Background: Little is known about the effect of exposure to air pollution during exercise or time spent outdoors on the development of asthma. We investigated the relation between newly-diagnosed asthma and team sports in a cohort of children exposed to different concentrations and mixtures of air pollutants., Methods: 3535 children with no history of asthma were recruited from schools in 12 communities in southern California and were followed up for up to 5 years. 265 children reported a new diagnosis of asthma during follow-up. We assessed risk of asthma in children playing team sports at study entry in six communities with high daytime ozone concentrations, six with lower concentrations, and in communities with high or low concentrations of nitrogen dioxide, particulate matter, and inorganic-acid vapour., Findings: In communities with high ozone concentrations, the relative risk of developing asthma in children playing three or more sports was 3.3 (95% CI 1.9-5.8), compared with children playing no sports. Sports had no effect in areas of low ozone concentration (0.8, 0.4-1.6). Time spent outside was associated with a higher incidence of asthma in areas of high ozone (1.4, 1.0-2.1), but not in areas of low ozone. Exposure to pollutants other than ozone did not alter the effect of team sports., Interpretation: Incidence of new diagnoses of asthma is associated with heavy exercise in communities with high concentrations of ozone, thus, air pollution and outdoor exercise could contribute to the development of asthma in children.

Purpose: Obesity is assumed to have a negative impact on self-esteem because of the associated social stigmatization in Western society. Studies of the psychological effect of obesity in children are inconclusive and limited, particularly pertaining to minority populations. Most studies have assessed global rather than domain-specific measures of self-esteem and hence, may have lacked specificity to detect impairment of certain aspects of self-esteem most closely associated with obesity. The purpose of this study is to examine the effect of adiposity and other environmental factors on measures of perceived competence and self-adequacy in 2205 black and white girls aged 9-10 years., Methods: Domain-specific measures of self-esteem were studied by race and degree of adiposity, using Harter's "Self-Perception Profile for Children". Three Harter scales deemed more relevant to obesity (social acceptance (SA), physical appearance (PA), and global self-worth (GSW)) were selected for univariate and multivariate linear regression models to examine relationships between self-esteem level and adiposity (measured by the sum of triceps, subscapular, and suprailiac skinfolds (SSF)), race, pubertal maturation, and parental education. The relationship between adiposity and Harter scores was further examined with LOESS curves and also by comparing the mean scores of each quintile of SSF by race, as well as inter-quintile differences within race., Results: Adiposity in general impacted negatively on the scores of all three selected Harter scales. There was also racial variation in the relationship between the scores and adiposity, with the magnitude of the effect somewhat less in black girls. White girls exhibited a significant inverse relationship between SSF and SA scores while, in striking contrast, there was no variation in scores in black girls across all ranges of adiposity. Although there was a significant inverse relationship between adiposity and PA and GSW in both groups, the slope was steeper in white girls, particularly at higher ranges of SSF. Non-linearity in the relationship between SSF and the scores was seen in SA and PA scales., Conclusions: The present study demonstrated a significant negative association between adiposity and the level of self-esteem in girls as young as 9 to 10 years. There were also intriguing racial differences in the selected domains of esteem. These results may help better understand cultural differences regarding the psychological impact of obesity and could be used to formulate appropriate strategies for public health policy.