Side by side air sampling was conducted using a PTFE filter membrane as dry sampler and an impinger containing a suitable culture medium as a wet sampler. Most of the samples were collected from two hospitals and few air samples were collected from private houses of non-hospitalized confirmed COVID-19 patients. The collected air samples were analyzed using RT-PCR. The results indicated that all air samples collected from the hospitals were PCR negative for SARS-CoV-2. While two of four air samples collected from the house of non-hospitalized patients were PCR positive. In this study, most of the hospitalized patients had oxygen mask and face mask, and hence this may be a reason for our negative results regarding the presence of SARS-CoV-2 in indoor air of the hospitals, while non-hospitalized patients did not wear oxygen and protective face masks in their houses. Moreover, a very high concentration of particles in the size range of droplet nuclei (< 5 µm) was identified compared to particles in the size range of respiratory droplets (> 5–10 µm) in the areas where patients were hospitalized. It can be concluded that using face mask by patients can prevent the release of viruses into the indoor air, even in hospitals with a high density of patients.

使用 PTFE 滤膜作为干式采样器​​和含有合适培养基的撞击器作为湿式采样器进行并排空气采样。大部分样本是从两家医院收集的，很少有空气样本是从非住院确诊 COVID-19 患者的私人住宅中收集的。使用 RT-PCR 分析收集的空气样本。结果表明，从医院采集的所有空气样本对 SARS-CoV-2 均呈 PCR 阴性。而从非住院患者家里收集的四份空气样本中有两份是 PCR 阳性的。在这项研究中，大多数住院患者都有氧气面罩和面罩，因此这可能是我们对医院室内空气中存在 SARS-CoV-2 的负面结果的原因，而非住院患者在家中没有佩戴氧气和防护面罩。此外，与患者住院区域的呼吸道飞沫尺寸范围（> 5-10 µm）的颗粒相比，发现了非常高浓度的飞沫核尺寸范围（< 5 µm）的颗粒。可以得出结论，即使在患者密度很高的医院，患者使用口罩也可以防止病毒释放到室内空气中。