This winter, save a few grey days, the sky over Beijing has been a brilliant blue, suggesting the city may finally be making progress against air pollution – an issue so dire in previous years that some periods were dubbed an “airpocalypse”.

The Ministry of Environmental Protection said that six cities in northern China reported falls in PM2.5 haze of at least 40% compared with a year earlier, including Beijing where the average PM2.5 level dropped by two-thirds (PM2.5 refers to hazardous particles with a diameter of less than 2.5 micrometers that can be inhaled into the lungs).