Impact of Airborne Pollen on Allergic Rhinitis and Asthma in an Arid Chinese City: A Time-Series Study from Lanzhou

Airborne pollen has become an important environmental driver of allergic respiratory diseases, especially under accelerating climate change. Lanzhou, a representative arid city in northwestern China, experiences distinct seasonal pollen peaks that may influence the incidence of allergic rhinitis (AR) and bronchial asthma (BA). This study aimed to investigate the short-term associations between daily airborne pollen concentrations and outpatient visits for AR and BA.

We collected daily outpatient visit data from a class A tertiary hospital in Lanzhou between April and October 2024, along with daily airborne pollen concentrations, meteorological indicators, and air pollutant levels. A distributed lag nonlinear model was applied to evaluate the nonlinear and lagged effects of pollen exposure on AR and BA. Stratified analyses were conducted by sex and age-group.

Elevated pollen concentrations were significantly associated with increased risks of both AR and BA, with the strongest effects observed within 1-3 days after exposure. Females and individuals aged 0-19 years showed higher susceptibility. Health impacts were more pronounced during the late summer to autumn pollen season, likely due to the predominance of highly allergenic taxa such as Artemisia and Chenopodiaceae. Thunderstorm events coincided with sharp increases in pollen concentrations and outpatient visits, indicating potential thunderstorm-related allergic exacerbations.

Daily airborne pollen exposure contributes to acute increases in AR and BA incidence in Lanzhou, particularly among children, adolescents, and females. These findings underscore the need for region-specific pollen monitoring, early warning systems, and targeted public health interventions to reduce the burden of allergic respiratory diseases under increasingly variable climatic conditions.