Impacts of biogenic emissions from urban landscapes on summer ozone and secondary organic aerosol formation in megacities.

The impact of biogenic emissions on ozone and secondary organic aerosol (SOA) has been widely acknowledged; nevertheless, biogenic emissions emitted from urban landscapes have been largely ignored. We find that including urban isoprene in megacities like Beijing improves not only the modeled isoprene concentrations but also its diurnal cycle. Specifically, the mean bias of the simulated isoprene concentrations is reduced from 87% to 39% by adding urban isoprene emissions while keeping the diurnal cycle the same as that in non-urban or rural areas. Further adjusting the diurnal cycle of isoprene emissions to the urban profile steers the original early morning peak of the isoprene concentration to a double quasi-peak, i.e., bell shape, consistent with observations. The efficiency of ozone generation caused by isoprene emissions in urban Beijing is found to be twice as large as those in rural areas, indicative of vital roles of urban BVOC emissions in modulating the ozone formation. Our study also shows that in the future along with NOx emission reduction, isoprene emissions from urban landscapes will become more important for the formation of ozone in urban area, and their contributions may exceed that of isoprene caused by transport from rural areas. Finally, the impact of biogenic emissions on SOA is examined, revealing that biogenic induced SOA accounts for 16% of the total SOA in urban Beijing. The effect of isoprene on SOA (iSOA) is modulated through two pathways associated with the abundance of NOx emissions, and the effect can be amplified in future when NOx emissions are reduced. The findings of our study are not limited to Beijing but also apply to other megacities or densely populated regions, suggesting an urgent need to construct an accurate emission inventory for urban landscapes and evaluate their impact on ozone and SOA in air quality planning and management.

Parental mediation of children’s vision care and digital technology use in Taiwan / 中国学校卫生

Objective@#This study aims to explore factors associated with parental mediation of children’s vision care and digital technology use.@*Methods@#By using a probabilityproportionate sampling method, a total of 3 249 parents of junior primary school students completed the selfadministered questionnaire in second semester of 2018 from Taipei and Pingtung. @*Results@#Parents had moderate scores in children’s vision care beliefs, selfefficacy and parental mediation. Children spent an average of 7 hours on digital technology use per week. Multiple regression analysis results showed that parents who had intact family, not providing children with personal digital technology devices, spent less time in digital technology devices, and had higher levels of vision care beliefs, higher mediation efficacy, and more cues to action were more likely to have higher levels of vision care mediation behaviors. Whereas children who were at senior grades, low household income, from nonintact families, owned personal digital technology devices, whose parents spent more time using digital technology devices and implementing low levels of parental mediation were more likely to spend more time using digital technology devices.@*Conclusion@#Schools and communities could provide more parental training and parentchild colearning opportunities to enhance parental mediation of children’s vision care behavior and reduce excessive digital technology use.