China has long been known to have a problem with air quality. High levels of pollution in almost every major city have been a concern for years. Recently, the Ministry of Environmental Protection said the general air quality of the nation's 74 key cities in 2015 was better than the previous year. Three other cities had reached standard levels of pollution but cities in the northern part of the country continue to have dangerous levels of smog.
The government in China has identified two "hot spots" in northern cities that, while levels lower than 2014, are still in the danger zone. The air quality is measured in terms of PM 2.5, which indicated particulate matter of less than 2.5 micrometers. While that sounds small, any form of particulate matter in the air is dangerous since it mixes with water droplets from rain and can be carried long distances. The environmental experts in China are stressing that prevention and better engineering of industry is the best way forward in reducing pollution and improving air quality.