RELX, founded by former Uber China head Kate Wang in 2018, is the biggest player domestically. It accounts for 68.8 per cent of the total market share, the company said, quoting data from Nielsen Research in April. E-cigarette companies currently operate in a regulatory grey area in China, as no national-level rules exist that provide standards for the safe manufacture and sale of nicotine salt-based e-cigarettes. Photo: Reuters