Beijing residents witnessed the city’s best winter air quality in five years this month, thanks to favourable weather and tough air pollution controls. There was a stretch of 25 consecutive days during which the air quality was rated “excellent” or “good”, a record for the past five years, and on the rare days when smog has appeared it has dispersed more quickly and been less severe. On the first smoggy day this month, December 2, the daily average level of PM2.5 – respirable suspended particles with a diameter of 2.5 microns or less that can be carcinogenic – was 202 micrograms per cubic metre of air. The second smog attack came on Thursday and Friday, with the government issuing a blue warning that the air would be “heavily polluted”. The PM2.5 level was above 200 at some monitoring sites in Beijing on Thursday and at all sites in the capital on Friday. Why blue skies over Beijing this winter could herald a turning point in city’s battle against pollution The air improved significantly from Saturday and is expected to remain “excellent” or “good” tomorrow, the first day of the new year. Beijing Daily said that in the past, heavy smog, with air quality index (AQI) readings of more than 300, would linger for seven to eight days on average. AQI considers six major airborne pollutants and usually reflects PM2.5 levels in winter. “Such air quality is unimaginable in other years,” the newspaper quoted Wang Xin, an air quality forecaster with the Beijing Municipal Environmental Monitoring Centre, as saying. Air pollution is known to increase the risks respiratory and heart diseases. The International Agency for Research on Cancer classified outdoor air pollution as a cancer-causing agent in 2013. The World Health Organisation’s guideline for a safe PM2.5 level limit is 25mcg per cubic metre of air. The air quality was rated “excellent” or “good” on 32 of the 36 days between November 15, when the capital turned on its heating plants, and December 20, with an average PM2.5 level of 38mcg per cubic metre of air, Beijing Daily reported on December 22. For the same period in the previous four years, the average PM2.5 level was 93mcg per cubic metre. Environmentalists attributed the unusually clean air to unprecedented efforts by the authorities to cut emissions, close polluting factories and switch to clean energy for winter heating. “Beijing’s city government has been trying to treat the winter diseases in summer, that is, working on cutting emissions even before the winter heating season began,” said Peng Yingdeng, a researcher at the National Engineering Research Centre for Urban Pollution Control. Beijing slaps ban on winter construction in bid to improve air quality Beijing residents have been banned from burning coal for heating and have switched to electricity or gas instead. Small factories or workshops that emitted pollutants have been shut down and the government also adjusted the production schedules of bigger polluting factories before winter arrived. Xie Shaodong, a professor of environmental sciences at Peking University, said the unprecedented steps taken by the government had ensured the skies were clearer this year. The Ministry of Environmental Protection ordered 28 cities, including Beijing, Tianjin and cities in the provinces of Heibei, Henan, Shandong and Shanxi deemed to be part of a “smog transmitting corridor”, to shut down small steel, metal processing, chemical and plastic factories by October. Burning coal has also been completely banned in several cities and small coal-burning boilers banned in other cities. All 28 cities were told to reduce their coal consumption this year. “You could smell the strong smell of coal last year when the air was bad, but never this year,” Xie said. “If you look around you would notice the unprecedented efforts taken to cut pollution.” The outdoor barbecue stalls that used to be seen in the streets were all shut down. Building sites and road works were shut down for four months in Beijing and six months in Tianjin, and some factories were ordered to suspend production on bad air days or for the whole of the heating season, which ends on March 15. China to send over 100 pollution inspection teams to cities around Beijing “Our rough calculations showed such measures cut pollution by 25 per cent, but the effect is better than that because of the favourable climatic conditions,” Peng said. “The climate this year has been the most favourable for dispelling pollutants in the past five years. Cold fronts and strong wind blew away pollutants even when the air was bad.” But Peng said the capital’s pollution problem had not been solved completely because emissions remained an issue and the climate was not always so favourable. China needed to switch from coal-fuelled power production to cleaner alternatives by 2020 and then spend another 10 to 15 years implementing further energy and transport improvements. The diesel trucks that carried cargo from city to city needed to be replaced by ships and trains and more electric and hybrid cars needed to be seen on city streets. China ranks provinces, cities on efforts to clean up environment “Only at that time will the air quality have little to do with weather conditions,” Peng said. “In 2050, weather conditions will have no effect on air quality at all.” Xie was more confident about the capital’s short-term air quality prospects, saying coal would not make a comeback as an energy source and the tough measures introduced by the government would not be relaxed. “I don’t think the winter air pollution will rebound next year even if the weather conditions worsen,” he said.