Physicochemical properties of respiratory droplets and their role in COVID-19 pandemics: a critical review

Ting Ge, Shengfeng Cheng

Table 1 List of representative nonaqueous components in a respiratory droplet

Nonaqueous components Brief description Salt and lactate Soluble, present as charged ions Cholesterol Insoluble, non-polar (except for the hydroxyl group at one end) Proteins and enzymes Amphiphilic, net charge depends on the sequence of amino acids and pH Lung surfactants Amphiphilic mixture of phospholipids and proteins Cell debris Organic waste from epithelial and immune system cells Bacteria Most bacterial cell walls carry negative charges Viruses pH-dependent surface charges