Species and quantity of airborne pollens in Shanghai as monitored by gravitational and volumetric methods.

BACKGROUND The prevalence of allergic diseases has markedly increased in the last decades. It is therefore important to assess the distribution of airborne pollen, the most important aeroallergen, for allergic disease prevention and control. OBJECTIVE To identify the species and quantity of airborne pollens, and observe their distribution characteristics in Shanghai, using gravitational (Durham Sampler) and volumetric (Rotorod Sampler 40) methods simultaneously. In addition, the correlation between both methods was analyzed to provide effective preventive measures for pollen-sensitized individuals. METHOD Pollen counts were monitored in the same area from November 1, 2009 to October 31, 2010 by samplers set at the same height and site. Pollen concentrations as well as any association between the two methods were determined. RESULTS Two pollen concentration peaks in Shanghai were observed from March to May (spring) and September to October (autumn). In spring, tree pollen was the main species, with a predominance of Broussonetia. In autumn, grass pollen predominated, with mostly Humulus. Thirty-two species were identified by both gravitational and volumetric methods. Five and seven additional species were identified exclusively by the gravitational and volumetric methods, respectively. Pollen counts obtained from both devices were significantly correlated (P<0.05). CONCLUSIONS Two methods were used simultaneously for the first time to monitor pollen counts in central urban Shanghai, showing two annual peaks. Broussonetia and Humulus were the predominant spring and autumn pollens, respectively. Pollen counts obtained by both methods were clearly correlated. Regional airborne pollen monitoring offers preventive measures for sensitized individuals and provides useful clinical information.