Atmosphere (Apr 2025)

Validation of the Automatic Real-Time Monitoring of Airborne Pollens in China Against the Reference Hirst-Type Trap Method

  • Yiwei Liu,
  • Wen Shao,
  • Xiaolan Lei,
  • Wenpu Shao,
  • Zhongshan Gao,
  • Jin Sun,
  • Sixu Yang,
  • Yunfei Cai,
  • Zhen Ding,
  • Na Sun,
  • Songqiang Gu,
  • Li Peng,
  • Zhuohui Zhao

DOI
https://doi.org/10.3390/atmos16050531
Journal volume & issue
Vol. 16, no. 5
p. 531

Abstract

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Background: There is a lack of automatic real-time monitoring of airborne pollens in China and no validation study has been performed. Methods: Two-year continuous automatic real-time pollen monitoring (n = 437) was completed in 2023 (3 April–31 December) and 2024 (1 April–30 November) in Shanghai, China, in parallel with the standard daily pollen sampling(n = 437) using a volumetric Hirst sampler (Hirst-type trap, according to the European standard). Daily ambient particulate matter and meteorological factors were collected simultaneously. Results: Across 2023 and 2024, the daily mean pollen concentration was 7 ± 9 (mean ± standard deviation (SD)) grains/m3 by automatic monitoring and 8 ± 10 grains/m3 by the standard Hirst-type method, respectively. The spring season had higher daily pollen levels by both methods (11 ± 14 grains/m3 and 12 ± 15 grains/m3) and the daily maximum reached 106 grains/m3 and 100 grains/m3, respectively. A strong correlation was observed between the two methods by either Pearson (coefficient 0.87, p p 2 = 0.76) and multiple linear regression models (R2 = 0.76) showed a relatively high goodness of fit, which remained robust using a 5-fold cross-validation approach. The multiple regression mode adjusted for five additional covariates: daily mean temperature, relative humidity, wind speed, precipitation, and PM10. In the subset of samples with daily pollen concentration ≥ 10 grains/m3 (n = 98) and in the spring season (n = 145), the simple linear models remained robust and performed even better (R2 = 0.71 and 0.83). Conclusions: This is the first validation study on automatic real-time pollen monitoring by volumetric concentrations in China against the international standard manual method. A reliable and feasible simple linear regression model was determined to be adequate, and days with higher pollen levels (≥10 grains/m3) and in the spring season showed better fitness. More validation studies are needed in places with different ecological and climate characteristics to promote the volumetric real-time monitoring of pollens in China.

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