ACKNOWLEDGMENTS
We appreciate Feifei Cao from Beijing Tongren Hospital for her contribution in the SPT and sera detection by UniCAP. We would like to thank Ming Wang and Bing Yan from Beijing Key Laboratory of Nasal Diseases for their comments on this manuscirpt. All the subjects are acknowledged for their participation in our survey. This study was supported by the special talent program of Hebei Province (Grant No. 070006-702800116049, 070006-702800117003).