Comparison of two methods for assessing the pollen allergy risk of urban parks in Chengdu City, China

The urban green space is an important inducer of pollen allergy. In recent years, the incidence of pollen allergy in China has increased from 5 % to 17.8 %, and it still rapidly increases. However, only few assessment methods of pollen allergy risk have been developed and applied in the urban green spaces. The feasibility and the accuracies of the assessment results of these methods has been unknown. Therefore, in this paper, the two best-known methods, total pollen concentration monitoring method and urban green zone allergenicity index (IUGZA) method, were both used to assess the pollen allergy risk of the same urban park (the People’s Park of Chengdu City, China). The impact factors and prediction consistency of both models were compared. The results showed that the proportion of medium and highly allergenic tree species reached up to 75.93 % in People’s Park. The total IUGZA value of this park was 0.69. A total of 36,171 pollen grains were collected here. The average pollen concentration of this park was 125.88 grains/cm2 per day. Both methods showed that the pollen allergy risk of the People's Park was the highest in spring. Correlation analysis showed that no vegetation characteristics of this park were correlated with IUGZA values and total pollen concentration. However, pollen concentration was extremely significantly correlated with air temperature and solar radiation in autumn and winter. Kendall’s concordance coefficient identified a super high consistency between total pollen concentration and IUGZA values in this park. This result means that both methods for assessing the risk of pollen allergy are effective. Based on the total pollen concentration, a polynomial formula was established for succinctly calculating the IUGZA. A three-step greening strategy is proposed to minimize the volume of allergen production and increase the well-being of users of urban parks in Chengdu City.