Hazy weather hung over Beijing on Wednesday with conditions in other parts of north China possibly worsening, forecasters said, although cold air sweeping in from the northwest is expected to help dissipate the smog. Experts attributed the haze in Beijing, which has lasted for several days, to poor atmospheric diffusion because of unseasonably weak cold air currents from the north. Visibility in most parts of Beijing dropped to less than 500 metres (546 yards), the China Meteorological Administration said. “I didn’t expect the smog to be so bad these days. The masks I’ve brought are almost used up,” said a 24-year-old Beijing tourist surnamed Gao. In some places, heavy winter fog was adding to the murky conditions and visibility was less than 50 metres in parts of Hebei province and Tianjin city. Moderate to heavy air pollution was expected in the Beijing-Tianjin-Hebei area and surrounding cities until Thursday, with short bouts of severe conditions, the environment ministry said after a meeting of its agencies. While the north of the region will improve in the first half of this month, pollution may persist in southern areas, it said.