Whilst Covid19 is thought to be predominantly transmitted by droplets, they can be various sized droplets, including fine droplets that can stay in the air for hours. Droplets not only released whilst coughing or sneezing. The simple act of talking, eating and even breathing can release them. (please see the attached video from Japan). This is why many governments, including our own, have now made mask wearing compulsory for the general public. There are many studies that have been done on this matter (such as this one: https://www.nejm.org/doi/10.1056/NEJMc2004973).
In addition, it is a known fact that virus droplets attach to larger particles in the air such as dust, pollution or other particles and then effectively becomes airborne. This is why maintaining clean air reduces the risk of viruses being transported through the air. There is increasing evidence that the Corona virus is airborne due to pollution and other particulate matter. (https://www.theguardian.com/environment/2020/apr/24/coronavirus-detected-particles-air-pollution)