COVID-19 (Corona Virus Disease 2019) is a severe respiratory syndrome currently causing a human global pandemic. The original virus, along with newer variants, is highly transmissible. Aerosol is a multiphase system consisting of the atmosphere with suspended solid and liquid particles, which can carry toxic and harmful substances; especially the liquid components. The degree to which aerosol can carry the virus and cause COVID-19 disease is of significant research importance. In this study, we have discussed the aerosol transmission as the pathway of SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2), and the aerosol pollution reduction as a consequence of the COVID-19 lockdown. The aerosol transmission routes of the SARS-CoV-2 can be further subdivided into proximal human-exhaled aerosol transmission and potentially more distal ambient aerosol transmission. The human-exhaled aerosol transmission is a direct dispersion of the SARS-CoV-2. The ambient aerosol transmission is an indirect dispersion of the SARS-CoV-2 in which the aerosol act as a carrier to spread the virus. This indirect dispersion can also stimulate the up-regulation of the expression of SARS-CoV-2 receptor ACE-2 (Angiotensin Converting Enzyme 2) and protease TMPRSS2 (Transmembrane Serine Protease 2), thereby increasing the incidence and mortality of COVID-19. From the aerosol quality data around the world, it can be seen that often atmospheric pollution has significantly decreased due to factors such as the reduction of traffic, industry, cooking and coal-burning emissions during the COVID-19 lockdown. The airborne transmission potential of SARS-CoV-2, the infectivity of the virus in ambient aerosols, and the reduction of aerosol pollution levels due to the lockdowns are crucial research subjects.

COVID-19（2019 年冠状病毒病）是一种严重的呼吸系统综合症，目前正在引起人类全球大流行。原始病毒以及新的变种具有高度传播性。气溶胶是由大气中含有悬浮固体和液体颗粒组成的多相系统，可携带有毒有害物质；尤其是液体成分。气溶胶携带病毒并导致 COVID-19 疾病的程度具有重要的研究意义。在这项研究中，我们讨论了 SARS-CoV-2（严重急性呼吸综合征冠状病毒 2）的气溶胶传播途径，以及 COVID-19 封锁导致的气溶胶污染减少。SARS-CoV-2 的气溶胶传播途径可进一步细分为近端人体呼出气溶胶传播和可能更远端的环境气溶胶传播。人类呼出的气溶胶传播是 SARS-CoV-2 的直接扩散。环境气溶胶传播是 SARS-CoV-2 的间接传播，其中气溶胶充当传播病毒的载体。这种间接分散还可以刺激SARS-CoV-2受体ACE-2（血管紧张素转换酶2）和蛋白酶TMPRSS2（跨膜丝氨酸蛋白酶2）的表达上调，从而增加COVID-19的发病率和死亡率。从世界各地的气溶胶质量数据可以看出，由于COVID-19封锁期间交通、工业、烹饪和燃煤排放减少等因素，大气污染往往显着减少。SARS-CoV-2 的空气传播潜力、病毒在环境气溶胶中的传染性以及封锁导致气溶胶污染水平的降低是重要的研究课题。