Concern for the economic recovery has weighed more over science as the government eased social distancing rule in public utility vehicles (PUVs).
The Department of Transportation (DOTr) announced it will implement the plan to ease the one-meter rule to 0.75 meter today. That is to help the transport sector bounce back from a slump because of lockdowns since March.
According to the plan, DOTr will further ease social distancing on September 28 to 0.5 meter. Then, on October 12, it will be 0.3 meter.
The Department of Health (DOH) has objected to the plan.
A safe distance against coronavirus transmission according to the World Health Organization (WHO) is at least one meter, the DOH said.
Why one meter? Is the one-meter rule a safe distance?
It depends to location.
The distance varies worldwide. It is one meter in Denmark, France, and China. Italy, Australia, and Germany recommend 1.5 meters, while in the United States it is 1.8 meters.
But there is no science for less than a meter distance.
Scientists consider four variables in recommending a safe distance of at least one meter.
These variables include respiratory droplets, infectious dose, viral load, and environment.
As the person talk, breathe, sneeze, and cough, he or she expells thousands of droplets. These droplets vary in size, ranging from millimeters to a thousand times smaller.
The smaller the droplet, according to experts, the longer it will stay on the air. Conversely, the bigger droplets fall to the ground quickly because of the gravity.
Experts had found out the sneeze droplets travel farther because of its speed. Droplets because of cough, most of them are larger, cannot travel longer.
This explains why social distancing differs from one place to the other.
Infectious dose refers to the number of copies of the virus a body needs to get infected. For influenza strains, the infectious dose requires thousands to millions of copy. There’s no available number of copies for the coronavirus so far.
The closer a person is to the carrier, the greater the chance for him or her to the infection.
Viral load is the number of copies of the virus that leaves the mouth. In COVID-19 patients, the viral load can reach up to hundreds of billions in every milliliter.
From person to another, the viral load varies. It also depends on the stage of the illness of the affected person.
Determining the viral load in the droplets will enable the calculation of the number of people exposed to the virus.
The environment will also influence the spread of the virus.
Air currents from air conditioners, for example, can blow the virus to different directions. The number of the droplets will reduce in a well-ventilated place.
Humidity and temperature will also affect the evaporation of water from the droplets.
So, it is a complex thing. This complexity, however, does not give credence to the reduction of the safe distance below one meter.