Boeing’s managing director for marketing, Darren Hulst, described how the epidemic has curtailed air traffic in China and Asia. On Jan. 6, he said, more than 3,250 flights originating in China connected more than 850 city pairs worldwide. On Feb. 21, less than seven weeks later, only about 700 such flights took off, connecting 240 city pairs. Hulst added that many of the February flights were air cargo; if only passenger service were counted, the slowdown “would be even more dramatic.”