Dust from the erosion of deserts in northern and northwestern China results in seasonal dust storms that plague the city; the Beijing Weather Modification Office sometimes artificially induces rainfall to fight such storms and mitigate their effects. In the first four months of 2006 alone, there were no fewer than eight such storms. In April 2002, one dust storm alone dumped nearly 50,000 tons of dust onto the city before moving on to Japan and Korea.