The relationship between outdoor atmospheric pollution by particulate matter and the morbidity and mortality of coronavirus disease 2019 (COVID-19) infections was recently disclosed, yet the role of indoor aerosols is poorly known . Since people spend most of their time indoor, indoor aerosols are closer to human occupants than outdoors, thus favoring airborne transmission of COVID-19. Therefore, here we review the characteristics of aerosol particles emitted from indoor sources, and how exposure to particles affects human respiratory infections and transport of airborne pathogens. We found that tobacco smoking, cooking, vacuum cleaning, laser printing, burning candles, mosquito coils and incenses generate large quantities of particles, mostly in the ultrafine range below 100 nm. These tiny particles stay airborne, are deposited in the deeper regions of human airways and are difficult to be removed by the respiratory system. As a consequence, adverse effects can be induced by inhaled aerosol particles via oxidative stress and inflammation. Early epidemiological evidence and animal studies have revealed the adverse effects of particle exposure in respiratory infections. In particular, inhaled particles can impair human respiratory systems and immune functions, and induce the upregulation of angiotensin-converting enzyme 2, thus inducing higher vulnerability to COVID-19 infection. Moreover, co-production of inflammation mediators by COVID-19 infection and particle exposure magnifies the cytokine storm and aggravates symptoms in patients. We also discuss the role of indoor aerosol particles as virus carriers. Although many hypotheses were proposed, there is still few knowledge on interactions between aerosol articles and virus-laden droplets or droplet nuclei.

最近披露了室外颗粒物大气污染与 2019 年冠状病毒病 (COVID-19) 感染的发病率和死亡率之间的关系，但室内气溶胶的作用却鲜为人知。由于人们大部分时间都在室内度过，室内气溶胶比室外更接近人类居住者，因此有利于 COVID-19 的空气传播。因此，我们在这里回顾一下室内源排放的气溶胶颗粒的特征，以及接触颗粒如何影响人类呼吸道感染和空气传播病原体的传播。我们发现，吸烟、烹饪、真空吸尘、激光打印、燃烧蜡烛、蚊香和熏香会产生大量颗粒，其中大部分是 100 nm 以下的超细颗粒。这些微小颗粒停留在空气中，沉积在人体呼吸道的深层区域，很难被呼吸系统清除。因此，吸入的气溶胶颗粒可能会通过氧化应激和炎症引起不良反应。早期流行病学证据和动物研究揭示了颗粒物暴露对呼吸道感染的不利影响。特别是，吸入的颗粒会损害人体呼吸系统和免疫功能，并诱导血管紧张素转换酶2上调，从而更容易感染COVID-19。此外，COVID-19感染和颗粒暴露共同产生炎症介质，会放大细胞因子风暴并加重患者症状。我们还讨论了室内气溶胶颗粒作为病毒载体的作用。尽管提出了许多假设，但对于气溶胶制品与载有病毒的飞沫或飞沫核之间的相互作用仍然知之甚少。