It only took a few weeks of 2018 before we hit our first stock market turbulence. For months, we've heard warnings that the equity market was due a sharp drop, given the massive gains over the past year or so. After years of steadily rising share prices, is volatility now the new normal on the markets? Is this all about inflation fears? Also in this programme, we look at the cost of cutting pollution in China, with a report from our correspondents in Beijing.