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Objective@#To investigate the association between sedentary bouts and cardiovascular disease (CVD) risk factors, and to provide a reference for controlling and reducing the incidence of CVD in children.@*Methods@#Cluster random sampling was used to select 356 students from five primary schools in Guangzhou. Sedentary behavior and physical activity were assessed using ActiGraph GT3X accelerometers, which were worn for 7 consecutive days. According to the sedentary bout duration of each participant, sedentary time was classified into categories of 1-<5, 5-<10, 10-<15, 15-<20 and ≥20 min bouts. Physical examinations were carried out to identify cardiometabolic risk factors. Multivariate linear regression was performed to analyze the relationship between sedentary bouts and CVD risk factors.@*Results@#After adjusting for confounding factors, the time accumulated in sedentary bouts of 5-<10, 10-<15, 15-<20 min in duration were positively associated with higher cardiometabolic risk scores ( B =1.24， 2.01 ，2.40), negatively associated with lower HDL ( B =-0.13，-0.21，-0.27). The time accumulated in sedentary bouts of 1-<5, 5-<10 , 10-<15, 15-<20 min in duration were positively associated with BMI levels ( B =1.07，1.89，2.86，3.65), and waist circumference ( B =2.79，4.81，8.04，10.14)( P <0.05).@*Conclusion@#These results suggested that sedentary bouts of 5-<20 min were associated with an unfavorable cardiometabolic risk profile. Our finding suggests no more than 20 min accumulated sedentary time for children.
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Objective@#To investigate the associations of moderate to vigorous intensity physical activity (MVPA) and screen time (ST) with emotional and behavioral problems in children and to provide evidence for related intervention measures.@*Methods@#In March 2017, a total of 4 922 children aged 6-12 years from 5 primary schools in Guangzhou were enrolled using stratified random cluster sampling method. Questionnaires were used to assess children s socio demographic information, MVPA, ST and emotional and behavioral problems. The associations of MVPA and ST with behavioral problems were explored by using generalized linear mixed models.@*Results@#Students with MVPA≥60 min per day accounted for 37.5%, and with ST≤2 h per day accounted for 87.7%. Children who were physically active showed lower scores for total difficulties, hyperactivity, and peer problems and higher score for prosocial than inactive peers( t =2.80, 2.47, 2.56, -1.97, all P <0.05). Also, children who spent less than 2 h ST per day reported lower scores for total difficulties, emotional symptoms, conduct problems, hyperactivity, and peer problems and higher score for prosocial compared to those with high ST( t =3.18, 3.35, 3.70, 3.80, -3.21, 4.97, all P <0.05). Children who met neither MVPA nor ST recommendations had significantly increased risks of total difficulties( OR=1.73, 95%CI =1.12-2.68), conduct problems( OR=1.45, 95%CI =1.02-2.05), peer problems( OR=1.93, 95%CI =1.11-3.36), and prosocial ( OR=1.55, 95%CI =1.08-2.23) than those who met both.@*Conclusion@#MVPA and ST are independently related to children s emotional and behavioral problems, and the risks of emotional and behavioral problems increased in children with insufficient MVPA and longer ST.
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BACKGROUND@#Particulate matter (PM), a major component of ambient air pollution, accounts for a substantial burden of diseases and fatality worldwide. Maternal exposure to PM during pregnancy is particularly harmful to children's health since this is a phase of rapid human growth and development.@*METHOD@#In this review, we synthesize the scientific evidence on adverse health outcomes in children following prenatal exposure to the smallest toxic components, fine (PM@*RESULTS@#Maternal exposure to fine and ultrafine PM directly and indirectly yields numerous adverse birth outcomes and impacts on children's respiratory systems, immune status, brain development, and cardiometabolic health. The biological mechanisms underlying adverse effects include direct placental translocation of ultrafine particles, placental and systemic maternal oxidative stress and inflammation elicited by both fine and ultrafine PM, epigenetic changes, and potential endocrine effects that influence long-term health.@*CONCLUSION@#Policies to reduce maternal exposure and health consequences in children should be a high priority. PM