Survey of air-borne allergic pollens in North China: contamination with ragweed

This paper presents the survey of 9 districts in North China with an object of understanding more about geographical distribution of air-borne pollens in relation with allergic diseases in the upper respiratory system. The findings prove to be a good guidance, beneficial both to the physicians who are treating the cases and to the patients who are receiving the treatments. The components of the peaks of the curves in Spring are nearly the same, they are usually formed of Ulmus (elm), Populus (poplar) and Selix (willow), with the exception that in the Spring curve of Lanzhou, Biota Orientalis dominates and at Huohot, Ulmus (elm) dominates. Like in the report on air-borne pollens in Peking, made by C. T. Chang as well as in our report on air-borne pollens survey in 9 districts in North China, Artemisia (sage) is found to be the chief component of the Summer-Autumn curve and the major offender in Summer-Autumn seasons in the etiology of upper respiratory allergic diseases. In contradistinction to Artemisia (sage), there are two exceptions such as in south China: In Shenghai, Ricinus (castor bean) and Humulus (Hops) are found to be the major offender instead of Artemisia (sage) and At Kwangzhou, Kwangdong province Wood Ephedra, Wild Amaranth (pigweed) are also found to be major offenders instead of Artemisia (sage). In addition to the major offender, Artemisia (sage) which was said to be dominant in Shenyang (Moukden) of Laoning province by Yuchin (cited from POLLINOSIS by Shih Ruei, Ragweed was first discovered at Shenyang (and Tehling, Fushuen and Dandong). A question is raised "How it came to China"? Preventive measures must be taken to eradicate it, otherwise it certainly will spread all over China.