The heavy smog that blanketed northern China over the weekend cleared somewhat on Monday, with flights in Beijing returning to normal, but it was likely only a brief respite.
More choking smog is expected to return to the wintry north within 24 hours.
Weather forecasts on Monday showed the smog would return to Beijing and the nearby city of Tianjin from Tuesday. It was expected to persist until Thursday in Hebei, the heavily industrialized province that surrounds the Chinese capital, and Henan and Shandong provinces, as the north battles freezing temperatures.