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Background There is a growing body of literature on the increasing prevalence of obesity in adolescents of Sub-Saharan African ancestry. However, limited data is available on the impact of obesity on pulmonary function. This study assessed the relationship between obesity and lung function in South African adolescents of African ancestry. Methods This was a cross-sectional study involving 10–14 year old adolescents recruited from middle schools of the Eastern Cape Province of South Africa. Anthropometric measurements were performed. Body mass index (BMI) was converted to percentiles for age and sex and used to classified obesity. Spirometry was performed to assess lung function. Chi-square test of association and binary regression analysis were used to assess the relationship between obesity and airway obstruction. Adjusted linear regression was used to determine the relationship between obesity and lung function parameters. Results A total of 540 adolescents were recruited for the study among which 77 (14.3%) were obese. Lung function parameters: forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were higher (p < 0.001) in obese than in non-obese adolescents while peak expiratory flow (PEF) % and FEV1/FVC ratio were lower (p < 0.05) in obese than non-obese adolescents. Obesity was associated (χ2 = 9.614; p < 0.01) with airway obstruction and obese adolescents were over 1.5 times more likely to have pulmonary obstruction (OR: 1.57; p < 0.05) than their non-obese counterparts. Anthropometric measures were positively associated (p < 0.05) with FVC, FEV1, PEF and/or FEV25-75 but negatively associated with FEV1/FVC ratio. Conclusions Obesity was associated with airway obstruction in South Africa adolescents of African ancestry.

The assessment of obesity in sub-Saharan Africa relies on cut-offs established from western populations. This study assessed anthropometric indices to determine optimal cut-off values for obesity screening in the South African adolescent population. A cross-sectional study involving 1144 (796 females and 348 males) adolescents aged 11–17 years from the Eastern Cape Province of South African was conducted. Anthropometric parameters were measured. Receiver operating characteristic (ROC) analysis was performed to assess the sensitivity and specificity of obesity screening tools and establish cut-offs. The optimal cut-offs for obesity in the cohort using waist-to-height ratio (WHtR) as reference were: neck circumference (NC) = 30.6 cm, mid-upper arm circumference (MUAC) = 25.9 cm, waist circumference (WC) = 75.1 cm, hip circumference (HC) = 92.15 cm and body mass index percentile (pBMI) = p85.2th. The new pBMI cut-off value at p85.2th improved the sensitivity of the test by approximately 30% compared to the CDC recommended BMI percentile (pBMIr) of p95.0th. When pBMI was used as reference, the optimal cut-offs in the cohort were: WHtR = 0.481, NC = 30.95 cm, MUAC = 27.95 cm, WC = 76.1 cm and HC = 95.75 cm. The WHtR optimal cut-off of 0.481 was close to the recommended cut-off value of 0.5. The predicted prevalence of obesity obtained using cut-offs from ROC analysis was higher than those from recommended references. All cut-off values for the various anthropometric measures generally increased with age for all percentile ranges. This study reveals a lower pBMI cut-off value, different from the CDC recommended cut-off, for screening obesity in a South African adolescent population. The study has established that the optimal pBMI cut-off for obesity screening may be ethnic-specific.

Background. Particulate matter (PM) air pollution is an important environmental health risk factor. Although some studies have shown PM to be associated with obesity and hypertension, very few studies have assessed the association of indoor PM specifically with obesity and blood pressure measures in children with respect to seasonal variation. Objectives. The present study investigated the relationship of PM with obesity and blood pressure variables in children across the winter and summer seasons. Methods. A comparative descriptive approach was adopted and school children from 10–14 years of age from selected rural and urban localities of the Eastern Cape Province of South Africa were assessed in winter and summer. Anthropometric measurements were taken, including height, weight, waist circumference, body mass index (BMI), and total fat mass (TFM), while blood pressure variables including systolic blood pressure (SBP), diastolic blood pressure (DBP) and heart rate (HR) were measured. Indoor air PM concentrations were measured in the classrooms in the presence of children. Results. The prevalence of obesity and hypertension in children were 13.4% and 5.1% in winter and 12.9% and 1.0% in summer, respectively. High blood pressure was more prevalent in children in rural areas, while the prevalence of obesity in children was higher in urban areas. Particulate matter was significantly (p&lt;0.05) higher in rural areas compared to urban areas. Obese children in summer had a greater than 3-fold association (AOR: 3.681, p=0.005) with 4th interquartile range (IQR) of PM5 and a greater than 3- and 4-fold association (AOR: 3.08; 4.407; p&lt;0.05) with 2nd and 4th IQR of PM10, respectively, than their overweight, normal weight or underweight counterparts. High blood pressure was not associated (p&lt; 0.05) with PM. Conclusions. High concentrations of indoor PM were positively associated with obesity in children in summer, particularly among rural children. This association could be accounted for by location and seasonal differences. Participant Consent. Obtained Ethics Approval. Ethics approval was obtained from the Health Sciences Ethics Committee of Walter Sisulu University, South Africa (Ref No: CHI011SCHU01). Competing Interests. The authors declare no competing financial interests.

Several studies have shown a relationship between indoor particulate matter and cardiovascular diseases in adults though this relationship is yet to be clarified in children and adolescents. This study purposed to investigate the relationship between indoor air particulate matter and blood pressure in 10-14 year old rural and urban children in Eastern Cape, South Africa. A cross sectional study of 10-14 year old children was carried out in selected rural and urban schools of the Eastern Cape. Anthropometry was performed and blood pressure measured. Indoor air particle counts were determine. Blood pressure parameters and body mass index (BMI) were converted to percentiles for height, sex and age. Prevalence of overweight/obesity were 10.9%/14.0% and hypertension/prehypertension were 12%/20%. Hypertension/prehypertension were more prevalent in rural compared to urban adolescents. All blood parameters were higher in rural adolescents and higher in rural girls compared to boys. In hypertensive/prehypertensive adolescents, systolic blood pressure (SBP) showed a strong correlation with BMI, waist, hip and mid upper arm circumferences (0.50, 0.51, 0.52, 0.53, 0.49; p<0.05 respectively) though SBP was only modestly associated with these variable in normotensive adolescents. Indoor particle counts were higher in rural schools. Blood pressure did not correlate with indoor air particulate matter though there was a weak correlation between PM2.5, 5, 10 and heart rate in rural adolescents. Indoor air particle failed to show any relationship with blood pressure parameters in urban adolescents. Rural adolescents had higher blood pressure and heart rates. Indoor particulate matter may be associated with blood raised pressure via sympathetic activation as suggested by higher heart rates.