BEIJING (AP) — China’s capital Beijing has been enveloped in the worst sandstorm in a decade, along with a wide swath of the country’s north. Traffic was snarled and more than 400 flights out of the capital’s two main airports were canceled. Such storms used to occur regularly in the spring time, as sand from the deserts in west of the country blew eastwards, affecting areas as far as northern Japan. The planting of trees and bushes has reduced the intensity of such storms, but the expansion of cities and industries has put constant pressure on the environment throughout China. The National Meteorological Center said the storm developed in the Gobi Desert in Inner Mongolia and would affect 12 provinces.