Beijing cancels, delays flights as sandstorm creates hazardous air

May 4 (UPI) -- The Beijing Capital International Airport said it canceled or delayed more than 50 flights due to a sandstorm that caused the city's air quality to reach hazardous levels.

Beijing's Environmental Monitoring Center said the city is under serious PM10 particulate pollution. The concentration of PM2.5 particles, which pose the greatest health risk, was 527 micrograms per cubic meter as of 9 p.m. on Thursday -- above the recommended World Health Organization limit of 25.

The airport said 15 flights have been canceled and 40 more are delayed for Thursday. Chinese authorities are urging residents, particularly for children and older adults, in northern China to avoid outdoor activity. The particulates are blowing in from neighboring Mongolia and China's Inner Mongolia Autonomous Region.

Chinese state media reported officials said the sandstorm began moving into Beijing Wednesday afternoon and covered the city overnight. The conditions are expected to last into Friday.

The capital city's air quality is regarded as the world's worst. A 2015 study indicated that China's air pollution is linked to 1.6 million deaths a year. The cause is attributed to industrial pollution, notably the burning of coal in factories, and Chinese air pollution tends to be most severe in the winter, when residents use coal-fired heating systems.

Sandstorms also affect Chinese cities, as people expand toward nearby deserts that are spreading due to deforestation linked to climate change. Chinese authorities have been planting more trees in attempts to slow deforestation and to reduce air pollution.