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

Airborne pollen has emerged as a critical environmental driver of allergic respiratory diseases, particularly under the accelerating influence of global climate change. This study investigates the short-term effects of daily airborne pollen concentrations on the incidence of allergic rhinitis (AR) and bronchial asthma (BA) in Lanzhou, a representative arid city in northwestern China. Utilizing outpatient visit data from a Class A tertiary hospital between April and October 2024, along with daily records of pollen concentrations, meteorological indicators, and air pollutant levels, we employed a Distributed Lag Non-linear Model (DLNM) to examine the non-linear and lagged relationships between pollen exposure and disease risk. Our findings reveal a significant association between elevated pollen levels and increased risks of both AR and BA, with the strongest effects observed within 1–3 days after exposure. Stratified analyses show that females and individuals aged 0–19 years are particularly susceptible. Moreover, health impacts were more pronounced during the late summer to autumn pollen season, likely due to the presence of highly allergenic species such as Artemisia and Chenopodiaceae. Thunderstorm events were also found to coincide with spikes in pollen concentrations and disease incidence, suggesting a potential link to thunderstorm-related allergic exacerbations. These results underscore the urgent need for region-specific pollen monitoring systems, early warning mechanisms, and targeted public health interventions to mitigate the burden of allergic respiratory diseases in vulnerable populations, particularly under increasingly volatile climatic conditions.

大气花粉已成为过敏性呼吸道疾病的关键环境诱因，在全球气候变化加速加剧的背景下尤为突出。本研究以中国西北典型干旱城市兰州为研究区域，探讨每日大气花粉浓度对过敏性鼻炎（allergic rhinitis，AR）与支气管哮喘（bronchial asthma，BA）发病风险的短期影响。本研究利用2024年4月至10月某三级甲等医院的门诊就诊数据，结合每日花粉浓度、气象指标及空气污染物水平的监测记录，采用分布滞后非线性模型（Distributed Lag Non-linear Model，DLNM）分析花粉暴露与疾病风险之间的非线性滞后关联。研究结果显示，花粉水平升高与过敏性鼻炎和支气管哮喘的发病风险增加存在显著关联，暴露后1~3天内的效应最为显著。分层分析表明，女性及0~19岁群体尤其易感。此外，夏末至秋季花粉季的健康影响更为显著，这可能与该季存在蒿属（Artemisia）、藜科（Chenopodiaceae）等强致敏花粉物种有关。研究还发现雷暴事件与花粉浓度峰值及疾病发病高峰同时出现，提示雷暴可能与过敏性疾病加重存在潜在关联。本研究结果凸显了构建区域特异性花粉监测系统、早期预警机制及针对性公共卫生干预措施的迫切性，以减轻易感人群的过敏性呼吸道疾病负担，在气候变化日益剧烈的背景下尤为重要。