Chinese officials have warned the residents of Chinese capital of Beijing to stay indoors and avoid heavy physical works. Dangerous particulate levels of air-quality of the city have been made public on Monday. Officials said, the air-quality index indicated that the density of PM2.5 had reached 400 micrograms per cubic metre in some areas of Beijing. Moreover, it was added that the level of air pollution was above the national and international standards and that the polluted air was expected to linger for two days. People in the streets were seen wearing masks while officials warned public saying, \"Elderly, young and sufferers of respiratory diseases need to remain indoors if possible\". Air pollution is a major problem inChina. Previously, public in China had reacted to increasing air pollution during winter season which brought the topic to the agenda of China\'s historical congress. In the scope of anti air pollution programs, the Chinese government suspended production facilities of many factories and warned for meeting the required conditions.