A worker tests an e-cigarette on the production line at KangerTech, one of China’s biggest vape product brands, on Sept. 24 in Shenzhen. Photo: VCG

Workers check e-cigarette pods on a production line. Some e-cigarettes take such cartridges, which are pre-filled with water, flavoring, nicotine, and propylene glycol and glycerin. Photo: VCG

Workers package pods for e-cigarettes. Photo: VCG

A worker cuts German-language warning stickers to be placed on pods on the production line at Shenzhen First Union Technology Co. Ltd., another large vape manufacturer, on Sept. 25. Photo: VCG

Workers box e-cigarettes on the production line. Photo: VCG

A worker processes an e-cigarette component. Photo: VCG

Workers assemble e-cigarette parts on the production line. Photo: VCG

Boxes of e-cigarettes with warning labels sit ready for export. Photo: VCG