Ahead of the Olympic Games, the country started to cooperate with the United Nations Environment Programme (UNEP) to address pollution levels, which were considered amongst the highest in the world, particularly as regards particulates and nitrous oxide levels. Beijing invested heavily in air quality improvements, which included the encouragement of using natural gas instead of coal; closure of major polluting industries; inspection and testing of vehicles in use; restrictions on vehicles used in the city; better supervision and management of construction sites known for high dust production; and upgrading 60,000 coal-burning boilers to reduce emissions. Further environmental protection initiatives included the conversion of more than 4,000 city buses to natural gas.
Temporary measures during the Olympic Games allowed the city to have the best possible air quality during the competitions, with clear blue skies which were dubbed “Olympic Blue”. The average daily Air Pollution Index in Beijing during the 2008 Olympic Games was 36 per cent lower than the average for the previous eight years. In addition, the concentration of the main air pollutants in Beijing gradually decreased from 2000 to 2008.
The efforts have continued since 2008, with major government initiatives introduced to help further improve air quality, notably the Beijing Clean Air Action Plan which runs from 2013 to 2022. This large-scale programme aims to clean up, relocate or close polluting industries; increase green energy generation; reduce traffic-related emissions; and reforest vast areas of barren land. A revised Environmental Protection Law came into effect in 2015, providing the most stringent regulations preventing and controlling air pollution to date, at both national and local levels.