Air pollution in China's Beijing has reached "dangerous" levels, and the capital of the world's most populous country is once again engulfed in thick smog and a sandstorm, according to a report published in state news agency Xinhua.

Quoting officials, Xinhua said that levels of Beijing's air pollution climbed to serious levels. Concentrations of hazardous particle called PM2.5, which poses serious health risks, jumped to 469 mgs per cubic meter at 10 a. m. on Thursday near Tiananmen Square, drastically up from an average of 275 mgs per cubic meter on the previous day.

As per the World Health Organization's recommendation, 24-hour exposure to PM2.5 should no higher than 25 mgs per cubic meter. However, the level dropped to 47 mgs by the evening yesterday.

The Beijing Municipal Environmental Monitoring Center blamed huge amounts of dust blowing in with strong winds from Mongolia for higher levels of pollutants in the air. The agency also urged people to remain indoors.

On Chinese social network Sina Weibo, the agency wrote, "We would hope that everyone stays indoors as much as possible and that people carry out appropriate measures for protection."

The air pollution has reached serious levels as the government is all set to open its annual National People's Congress on 5th of March 5 to discuss growth policies. The government has urged people to show patience as it addresses pollution.