In February 2014, hazardous smog in Beijing once more made headlines across the world. Particulate matter measurements (PM2.5) temporarily exceeded the 25 micrograms 24-hour mean considered safe by the World Health Organization by 15 times. For one day Beijing’s authorities raised its air pollution alert to orange, the second highest of the four-tiered system. To tackle the repeating smog events, Beijing released its Clean Air Action Plan last autumn, outlining the introduction of a congestion charge and an ex