Regional and seasonal variation of airborne pollen and spores among the cities of South China

The composition and relative abundance of airborne pollen in urban areas of south China are strongly influenced by geographical location, vegetation, climate, and sampling device. This paper summarizes the latest reports on air pollen for 12 major cities in southern China from 1986 to 2017. The most significant taxa across all sites are Pinaceae, Poaceae, Cupressaceae, and Platanus, making up over 50% of the total airborne pollen in urban environments throughout the years. Clear shifting has been observed from long pollen seasons in the tropics to shorter periods in the south middle and north subtropical regions. There is also a discernible shift in the initiation and length of the pollen season towards higher latitudes. Both reflect the strong influence of solar radiation incidence on pollen production during spring and summer months in the southern urban areas. In this study, the comparison between airborne pollen and meteorological data indicates that the airborne pollen concentration was positively related to temperature but negatively related to precipitation and relative humidity. This study reveals that the consistent wind speed over the year had a very little but positive effect on pollen and spore concentration. The active sampler (volumetric method) in Guangzhou and Zhanjiang collected more spore and pollen species than the passive sampler (gravity method) in other cities. Understanding the future potential impacts of climate change on the phenological cycles and range of allergenic species is a critical step in the advancement of aerobiology studies in south China.