-By Vikram Murthy, Director, Univac Environment Systems
The escalation in the spread of the coronavirus (COVID-19) is alarming. In India, there are over 10,000 confirmed cases with coronavirus (as on April 14) that have been detected. The solution primarily lies in its isolation and prevention. The airborne nature of the virus puts the pandemic – and its prevention and containment at the doorstep of the medical fraternity and in the realm of the international HVAC industry that guides building climate control worldwide. People must follow some precautions for the safe operation of occupied spaces during the prevalence of COVID-19.
The COVID-19 virus is transferred via infected microscopic airborne particles and contaminated aerosol droplets. These can be ingested by humans when they come in contact with surfaces where the virus is and once it enters the human via direct airborne ingestion through the nasal passage, it finds its way into the lungs. The COVID-19 infection may result in deteriorating health – or body immunity may resist the infection but the patient may remain a carrier. Testing for COVID-19 symptoms that occur is the prescribed procedure that all must strictly follow. Close contact with those who are infected and coughing or sneezing without mask protection can spread the infection.
Another mode of transmission involves intermediate surfaces that have been infected by contact by carriers of the COVID-19 virus. The airborne particles may quickly drop down to the ground, but the virus may stay active for hours on surfaces. The period of active infection deposited on surfaces hasn’t been reliably determined yet.
There are at least two distinct ways of transmitting a COVID-19 infection, it is the best to follow prescribed hygiene and ventilate occupied spaces constantly. At this time when outdoor temperatures across India are still low, simple natural ventilation is the correct guideline for occupied spaces. As summer sets in and if air conditioning are applied, then recirculation of air at homes and in small commercial spaces must be accompanied by constant outdoor air ingress and exhaust by a natural ventilation process or by forced ventilation. For centrally air-conditioned spaces, the same must apply with outdoor air being filtered and filters kept clean. This must continue until the occurrence of COVID infection is completely eliminated.
No known air filters or air purifiers can arrest the COVID-19 virus, and no tests in this regard have been conclusive yet. That’s why natural ventilation is being presently advised. Any claim that filters, whether in air conditioners or in air purifiers, can arrest the virus must be rejected – till laboratory tests prove the correct airborne arrestation applied for conditioned indoor spaces with recirculation that can contain the spread of COVID-19 virus if present and airborne. HEPA filtration can arrest the virus if it is present in larger droplets and then such filters shall be due to be replaced.
Whether Electrostatic Filtration can arrest the COVID-19 virus is not proven yet. Disinfection by UV light or other medically proven methods of arresting airborne infection can certainly help but such treatment is restricted largely to larger commercial air conditioning systems and in hospitals where their installation and control is carefully done.
To reduce the COVID-19 virus, higher indoor temperatures along with ceiling fans and natural ventilation is recommended. Closed and dry spaces and environments with recirculated cold air will transfer infection if it is present. Special care in building operation must become mandatory in commercial centrally air-conditioned spaces – to maintain higher temperature and increased ventilation – until the COVID-19 virus is eradicated and is absent for many months. The use of energy recovery that allows cross-contamination must be avoided. Air filters must be replaced regularly; not washed and replaced. Air conditioning indoor temperatures between 28 to 30 degrees are advised. Humidity between 40 per cent and 65 per cent is advised too. The spread of the virus if present will decline at higher temperatures higher humidity and with good ventilation.
As summer sets in, if COVID-19 has not been completely eradicated and air conditioning is applied to occupied spaces, hen temperatures 28 Degrees and higher with good ventilation and air circulation with ceiling fans is recommended. The human body shall adjust to these indoor climate conditions in time and naturally. It will reduce the risk of infection and the consumption of energy.
The views expressed at this time are preliminary and are based on available international advisory. Comprehensive guidance by researched findings shall be available issued soon. The author does not guarantee nor bears liability for the prevention of COVID-19 by application of this preliminary guidance.
Univac Environment Systems Pvt Ltd, Mumbai