While falling rain washes pollen grains from the atmosphere, rain can also induce pollen rupturing into submicrometer pollen fragments. Compared to intact pollen, such fragments can penetrate deeper into the human respiratory system and persist longer in the atmosphere. Herein, we provide the first online characterization of pollen fragments during thunderstorms and rain events. For the first time, we combine single-particle fluorescence spectroscopy with offline measurements of chemical tracers to provide direct evidence of atmospheric pollen fragments. We show a significant increase in pollen fragments with diameters of 0.25–1.0 μm coincident with precipitation. Pollen fragment concentrations peak during convective thunderstorms with strong downdrafts, high rates of rainfall, and numerous lightning strikes, although lightning is not required for the fragments’ release. After storms, pollen fragments persist in the atmosphere for several hours. Our results show that while pollen grains decrease substantially during rain, peak concentrations of submicrometer pollen fragments occur during rain events and then persist for several hours. This study provides new information on the abundance, size distribution, and meteorological drivers of pollen fragments in the atmosphere. Because pollen fragments potentially carry allergens and thunderstorms are predicted to increase in frequency and strength, understanding human exposures to pollen fragments is increasingly important.

中文翻译：

---

春季雷暴期间大气花粉碎片的特征

雨水从大气中冲洗花粉粒时，雨水也会促使花粉破裂成亚微米级的花粉碎片。与完整的花粉相比，此类碎片可以更深地渗透到人体呼吸系统中，并在大气中持续时间更长。在此，我们提供了雷暴和降雨事件期间花粉碎片的第一个在线表征。我们首次将单粒子荧光光谱与化学示踪剂的离线测量相结合，以提供大气花粉碎片的直接证据。我们发现直径为0.25-1.0μm的花粉碎片与降水量显着增加。在对流雷暴期间，花粉碎片的浓度达到峰值，这有强烈的向下气流，高降雨率以及无数雷击，尽管碎片释放不需要闪电。暴风雨过后，花粉碎片会在大气中保留数小时。我们的结果表明，尽管花粉粒在降雨期间会大量减少，但亚微米花粉碎片的峰值浓度会在降雨期间发生，然后持续几个小时。这项研究提供了有关大气中花粉碎片的丰度，大小分布和气象驱动因素的新信息。由于花粉碎片可能携带过敏原，预计雷暴会增加频率和强度，因此了解人类对花粉碎片的暴露越来越重要。亚微米花粉碎片的峰值浓度在降雨期间发生，然后持续数小时。这项研究提供了有关大气中花粉碎片的丰度，大小分布和气象驱动因素的新信息。由于花粉碎片可能携带过敏原，预计雷暴会增加频率和强度，因此了解人类对花粉碎片的暴露越来越重要。亚微米花粉碎片的峰值浓度在降雨期间发生，然后持续数小时。这项研究提供了有关大气中花粉碎片的丰度，大小分布和气象驱动因素的新信息。由于花粉碎片可能携带过敏原，预计雷暴会增加频率和强度，因此了解人类对花粉碎片的暴露越来越重要。