In a comparative analysis with increasing humidity and temperature the scientists found that at 35°C and 40% relative humidity, a droplet can travel 8 feet while at 41°C and 80% humidity, it travels 12 feet.
Beware of cough droplets it it can travel longer distances when weather is humid! The recurrent showers which have drenched the northern parts of the country over the last few days might bring cheers on the face of farmers and give relief from the heatwaves but it might also lead to a spike in the number of Coronavirus cases across the country. For most Indians who adhere to social distancing when they move out of their homes, this study and its finding can be an eye-opener.
Curious to know more about how far cough droplets can travel? A study conducted by the researchers from the University of California San Diego (UCSD), Indian Institute of Science (Bengaluru), and University of Toronto has found that the respiratory droplets might travel further and keep hanging longer in the humid and cold climate caused by rains, the IE reported. The study which has brought salient findings about the impact of climate on the spread of Coronavirus has been published in the journal Physics of Fluids. This is not the first time that scientists have hinted at the correlation between the Coronavirus and climate. Reports have also warned that a second brutal wave of the disease could come in the winters.
The researchers relied on a mathematical model which they used to predict the spread of the disease and contribution of respiratory droplets to it. The model is based on the combination of the physics of droplets and the spread of disease on population-scale interaction. Professor Saptarshi Basu from IISc, Bengaluru told the Indian Express that his team included a detailed kinetics model regarding infection as the respiratory droplets travel and evaporate. He also said that the model is based on the molecular collision theory adapted from combustion.
As far as the findings of the study go, the scientists have found that subject to the prevailing weather conditions an average droplet might travel between 8 feet and 13 feet from the person who has emitted it. In a comparative analysis with increasing humidity and temperature the scientists found that at 35°C and 40% relative humidity, a droplet can travel 8 feet while at 41°C and 80% humidity, it travels 12 feet. The movement and impact of wind was not taken into account in the study. The findings should ring alarm bells among health authorities as earlier it was believed that six feet distance between individuals was enough to stop the spread of virus.
However, contrary to other reports and analysis the study has substantially discounted the impact of cold weather on the spread of the virus. It has found that more than the cold weather or winter season, humidity could prove more fatal in the spread of Covid-19.
On the question of the impact of cold weather on the virus spread, Professor Basu said that it would also increase the lifetime of the virus but not as much as humidity or damp weather. Apart from the impact of climate, the study also found that the distance travelled and longevity of the droplets depended on their size as well. Droplets in the range of 14-48 microns stay for a long time in the atmosphere before the process of evaporation. On the other hand, the smaller droplets very quickly evaporate into the sky. Extremely large droplets in the range of above 100 microns are more likely to settle on the ground.