From anther dehiscence to its atmospheric journey, airborne pollen grains can come into contact with other particulate matter (PM) and the external wall of pollen grains can be polluted by adhered atmospheric particles. Pollen and PM are some of the most common asthma triggers. The aim of this review was to discuss literature reporting pollen–particle complexes in the outdoor environment so their potential role in enhancing the risk of allergy could be examined. Twenty-five studies report pollen–particle complexes observed in outdoor conditions. PM adhesion onto the pollen surface was investigated in the literature by three different experimental approaches: direct collection from anthers, bulk exposure of pollen to PM in polluted areas, and direct sampling of airborne pollen during pollination. Four processes are proposed to explain deposition of PM on the surface of pollen grains: sticking of particles to anthers and pollen during dehiscence, airborne pollen-particles coagulation, wet and dry scavenging of pollen and particles, and co-deposition of PM and pollen in the respiratory system. Despite potential adverse health effects, the magnitude of pollution of pollen by PM is poorly understood. To address this issue, we suggest the following guidelines for research: (1) Possible artifacts during sampling and handling of anthers must be carefully avoided; (2) Control pollen grains (i.e. non-polluted) should be carefully selected; (3) A better knowledge of pollen atmospheric deposition and resuspension is needed; (4) The health effects of pollen-particles complexes need more attention regarding symptoms and allergic sensitization; (5) Use of individual pollen samplers could give a depiction of the degree of pollution of pollen that is actually inhaled.

中文翻译：

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大气颗粒物附着在花粉上：综述

从花药开裂到大气传播，空气中的花粉粒会与其他颗粒物 (PM) 接触，花粉粒的外壁会被附着的大气颗粒物污染。花粉和 PM 是一些最常见的哮喘诱因。本综述的目的是讨论文献报道户外环境中的花粉-颗粒复合物，以便检查它们在增加过敏风险方面的潜在作用。25 项研究报告了在室外条件下观察到的花粉颗粒复合物。文献中通过三种不同的实验方法研究了 PM 粘附在花粉表面上的情况：从花药中直接收集、在污染地区大量接触 PM 的花粉以及在授粉过程中对空气中的花粉进行直接采样。提出了四个过程来解释 PM 在花粉粒表面的沉积：开裂过程中颗粒粘附在花药和花粉上，空气中的花粉颗粒凝结，花粉和颗粒的湿和干清除，以及 PM 和花粉在花粉中的共同沉积。呼吸系统。尽管存在潜在的不利健康影响，但人们对 PM 对花粉的污染程度知之甚少。为了解决这个问题，我们建议遵循以下研究指南： (1) 必须小心避免在采样和处理花药过程中可能出现的人工制品；(2)防治花粉粒(即无污染)应慎重选择；(3) 需要更好地了解花粉大气沉降和再悬浮；(4)花粉颗粒复合物对健康的影响需要更多关注症状和过敏性致敏；