According to a new study on the spread of the coronavirus pandemic, researchers found that coughing or sneezing in public is not as harmful as previously thought, as the study indicates that the novel coronavirus can spread from symptomatic carriers merely through conversation.
Researchers in Japan stated that coronavirus carriers can spread the virus through small aerosol droplets that are expelled during exhalation and while talking to another person in close or enclosed spaces. Notably, scientists often use lasers and smoke to study the airflow emitted from the body when two people are talking in different positions and distances. For instance, sitting in a barber's chair for a haircut or sitting in a doctor's office represents two entirely different situations. In this specific study, the team used e-cigarettes to create artificial viral droplets, as the liquid in them—a mix of glycerin and propylene glycol—allows scientists to easily track and visualize airflow patterns.
The study's author, Dr. Kiko Ishii, stated in a press release from the American Institute of Physics: "We analyzed the characteristics of exhalation spread with and without a mask while the person was standing, sitting, bending down, or lying on their back." The researchers repeatedly recorded the resulting vapor cloud while participants performed the traditional Japanese greeting "onegaishimasu" in various relevant postures, with the experiment conducted in a local hair salon in Tokyo. Dr. Ishii added, "A great deal of direct face-to-face interaction occurs not only in beauty salons but also in long-term healthcare centers."
The experiments showed that the air exhaled during a conversation by an unmasked individual often falls due to gravity, so if there is another person below, as during a haircut, the customer could become infected. However, if the speaker is wearing a protective mask, those particles typically stick to their body and flow upwards, as their body is warmer than the surrounding air. Even while wearing a mask, if the hairstylist leans over the customer, it is possible for an aerosol cloud to separate from them and fall onto the customer, leading to potential virus transmission. Additionally, the study's authors noted that employees working in such industries, where they face customers directly, should wear both a face mask and a face shield at all times.
