阅读理解 Headaches associated with air travel appear to be a“huge and painful problem”, Israeli researchers report． In a study of 906 men and women who had traveled more than once by plane, nearly 6％ reported that they experienced headaches associated with flying． There are a number of mechanisms that could contribute to headaches during air travel, including stress, poor air quality, engine noise and changes in barometric pressure(大气压), the investigators note．To investigate the prevalence(盛行)of flight-associated headaches, they surveyed visitors to the travel clinic at their medical center． More than one in five of the study participants had headaches at least once a month that weren't related to flying, the researchers found．But just over half of the 5.7％ who reported flight-associated headaches suffered headaches this frequently．They were also slightly more likely to have migraines(偏头痛)．Two-thirds of those who suffered flight-associated headaches were women, and one-third had a family history of headache． Among the flight-associated headache sufferers, 19.2％ said they had headaches every time they flew．Nearly a quarter said their headaches got worse as the plane climbed, while a fifth said the pain became worse as the plane descended to the Dead Sea, which is about 400 meters below sea level, suggesting that barometric pressure may be a factor． This study, the researchers conclude, suggests that flight-associated headache “seems to affect a significant number of the travel population”． | 
