What are the effects of migration from provinces to Metro Manila in terms of the spread of covid 19 pandemic?
Answers
Answer:
Explanation:
Metro train services in major cities across India were cleared to run from September 7, 2020, for the first time since March, even though novel coronavirus disease (COVID-19) cases significantly increase every day.
COVID-19 hit public transit systems in New York, United States and London, United Kingdom badly, causing several deaths, including those of the train operators, other employees and passengers.
There is, thus, a need to exercise abundant caution to ensure safety measures in the running of the metro. It becomes imperative for metro services to run with safety measures against the SARS-CoV-2 virus that causes COVID-19, especially given the potential of the metro to become a hub of viral aerosol transmission and super-spreading events (SSE).
Virus-laden aerosol droplets — tiny particles of less than five micrometres and droplets that range from 5-50 microns — are emitted by COVID-19 patients from their mucosal membrane when they talk, breath, shout, sing, etc.
These droplets fall to the ground — because of their weight and gravity — while viral aerosols linger in the air as they are lighter and float for a few hours when their moisture shield dries up.
How aerosols are transmitted
Six-foot social-distancing fixes droplet spread to a large extent, but studies have found viruses 15 feet away from patients in hospitals due to aerosol transmission. Aerosols are, however, a little more complex to deal with, unless additional measures are taken.
Aerosol virions (virus particles) expelled by the patients can circulate in poorly ventilated spaces. Anyone breathing in them can get the viral load. The time spent in such spaces is also directly proportional to air quality and crowding.
Aerosols can sneak into heating, ventilation and air-conditioning (HVAC) systems and are subsequently spread from recirculated air. Metro trains and stations rely on air-conditioning. Special attention must, thus, be paid to minimise aerosol spread by ensuring ventilation and air circulation.
SSEs are incidents where one person with a viral load can spread the virus to tens of others in a specific area and in a short duration of time. Thousands of such SSEs were documented across the world.
The distinct pattern in these cases is they occur mostly in indoor settings, with aerosol transmission being the suspected culprit. We need to prevent SSEs and make metro systems safe.
To aid people to remember and watch out for aerosol transmission and to avoid SSE, we propose a Triple A (AAA) system.
Area: Avoid crowded spaces with too many people hanging around
Activity: Minimise talking, singing, shouting, exercise and dancing in crowded areas
Air quality: Avoid places with poor ventilation, high carbon dioxide (CO2) concentration and little air circulation, especially when air reeks of body odors or strong smells, including those of garlic, tobacco or perfumes
Metro systems can avoid SSEs
Metro trains have their doors and windows closed when in transit. They always rely on air-conditioning. Metro stations are mostly indoors or enclosed outdoors, with their entrances and exits being indoors having long corridors.
There is established evidence from studies published in reputed scientific journals of the virus being reportedly airborne, with aerosol spread being one of the reasons along with fomite and droplet transmissions.
The World Health Organization and the Union Ministry of Health and Family Welfare called for hand-washing and social-distancing, along with wearing masks.
Metro trains are, thus, potential aerosol transmission hubs and need special attention. The Union Ministry of Housing and Urban Affairs, in its standard operating procedures, made a cursory mention of improving ventilation.
But given the scope for any malfunctions in ventilation, additional measures must be taken. A well-documented study attributed the super-spread of influenza cases in a commercial airplane in Alaska to a ventilation failure. The metro systems should not take such chances.
The CO2 level indicates surrogate aerosol activity and must be monitored on trains and stations. They should, if possible, indicate CO2 levels on light-emitting diode boards to alert people of possible aerosol spread. Metros must use at least 12 air changes per hour to dilute aerosol. High-efficiency particulate air filters usage must be explored in HVAC systems.