Spring may bring happiness to some, but for one in five Tokyo residents, it also carries a little something extra in the air, according to a survey released Oct. 14 by the Tokyo Metropolitan Government.The number of people allergic to cedar pollen has doubled over the past 10 years, raising the ratio of those suffering from such symptoms as itchy eyes and runny noses to 19.4 percent, the survey said. The survey also showed that an increasing number of young people under 15 suffer from pollen allergies. The percentage of allergy patients in that age bracket in Chofu, one of the surveyed areas, increased to 21.5 percent from 7.6 percent in 1987.Questionnaires were sent in November to 3,600 people living in Akiruno and Chofu cities and in Ota Ward. Slightly more than 58 percent responded. People aged 30 through 44 suffer the most from allergies. More than 30 percent of this age group in each of the three cities reported allergy problems.In Akiruno, where there is five times more pollen in the air due to the presence nearby of rich forests, 41.4 percent of that age group has allergies, compared with 25.7 percent of all respondents in the city, according to the survey. The reason for the overall increase is unclear, but government officials pointed out that large numbers of cedars planted in the 1950s have started to mature and release pollen.