Dragged down by falling global markets, the Sensex at the Bombay Stock Exchange dropped 281 points, or 1.6 percent, to close below the 17,000 level, at a nearly one-month low of 16,877, on Monday.The Nifty at the National Stock Exchange fell 87 points, or 1.7 percent, to 5,118. Key Asian markets in Japan, China, Hong Kong, South Korea and Singapore plunged between 1 percent and 3 percent, on fresh euro zone debt worries, and China growth concerns. The European markets also took a hit.