Coronavirus Risk increases in closed, crowded and poorly ventilated environments
El Ministry of Health has included the scientific evidence that point to the aerosol sprays like a coronavirus transmission going and has established that the risk increases in closed and crowded environments, especially stuffy, and with activities such as exercise, talking loudly, yelling, or singing.
It has done so in the last update of the information document scientific-technical of coronavirus disease, the covid 19, in which for the first time he dedicates an extensive section to aerosol transmission and has reviewed all the current evidence and research findings that they have published expert international epidemiologists and engineers in this area.
Research that indicates that the classic paradigm for professionals in Public Health and the control of communicable diseases, which classifies respiratory emissions in droplets (greater than 5 microns) and aerosols (less than 5 microns), “has to be reviewed“.
According to the document, only droplets greater than 100 microns have a behavior “support“: they descend to the ground in a few seconds due to the effect of gravity and can travel a maximum distance of two meters from the emitter.
Any other respiratory emission below that size is considered an aerosol, that is suspended in the air for a time (a few seconds and even hours) and can be inhaled at a distance greater than two meters from the emitter or even in the absence of it, if the particles are still suspended in the air.
Depending on their size, 15-100 micron aerosols can arrive at upper respiratory tract; those between 5 and 15 microns to the trachea and main bronchi, and those of less than or equal to 5 microns have the ability to reach the alveoli.
The scientific community has established three conditions for the coronavirus It is transmitted through aerosols: the first, that these particles contain viable microorganisms.
These microorganisms must be present in a sufficient quantity and demonstrate its ability to generate infection, “especially in certain circumstances”, such as proximity for a long time and in closed and poorly ventilated spaces, conditions in which “several transmission mechanisms can coexist”.
The last condition is that the Target tissues for these microorganisms must be accessible for aerosols any size with entry ports anywhere in the respiratory tract.
In view of this, Sanidad concludes that “in the current state of scientific knowledge there is consistent scientific evidence that allows us to affirm that the transmission of the SARS-CoV-2 virus by aerosols an additional transmission path should be considered previously recognized (contact with respiratory secretions, fmites) “.
These aerosols could both impact and settle on the upper respiratory tract as being inhaleds; the risk of transmission “increases in short distance, in closed and crowded environments, especially poorly ventilated, and if activities are carried out that increase the generation of aerosols such as exercising, talking loudly, yelling, or singing“.
On the other hand, the update of the document lists the sequelae that this disease could leave; In its latest version, from the end of August, it claimed that at that time it was unknown whether there were any or not.
However, complications such as pulmonary fibrosis, impaired lung function, neuropathies, cardiac and musculoskeletal system involvement.
Updating this document also adds evidence on risk groups and notes that the pregnancy it is a situation with a higher risk of complications from both the clinical course of the disease and the pregnancy itself.
However, in neonates, although prematurity is more frequent, the clinical course of covid has a good prognosis.