Not all battles are won by arms and ammunition; the current battle requires doctors, nurses, cashiers, warehouse crew, delivery crew, sanitation workers, truck drivers, vendors and pharmacists. They are working relentlessly to ensure that we win the battle against COVID-19 with minimum casualties. In such a situation, prevention of spreading of the virus to these workers is tantamount to protecting the lives of the patients. Studies done on the transmission of the virus provide a relatively simpler solution to improve the containment of the virus and potentially save countless lives.
How Indoor Air Quality affects virus transmission?
Numerous studies have established a correlation between the relative humidity levels maintained in buildings and the risk of contracting illness due to transmission. Sterling report published in 1985 suggested that at room temperature, the ideal humidity level for any structure is 40-60% since it drastically minimizes the growth of biological organisms and the speed of chemical interactions taking place.Furthermore, another research by Casanova et al, 2010showed that the survival rate of coronavirus reduced exponentially when exposed to mid-range humidity (50% RH) as opposed to dry (20% RH) or damp (80% RH) air. The mid- range humidity level also mitigates the rate of transmission of the virus in the building. As the humidity level increases, the viral droplet settles out of the air owing to its larger size whereas in areas with low humidity, the droplets can remain airborne for prolonged periods of time due to rapid evaporation. It results in an increase in the time, distance of the transmission and ultimately the percentage of people contracting the virus.
Seasonality of COVID-19, SARS CoV and MERS CoV
The role that humidity plays in transmission of viruses such as influenza, coronavirus & SARS can be gauged from the seasonality of these viruses. Since the level of relative humidity is extensively low during the winters, it makes the indoor air drier which results in an increase in the rate of infections. The strategy being used for coronavirus containment relies on this information – during the summers with humidity levels around 40-60% RH, the rate of infections will reduce; however, this is not a sustainable solution. If a healthy indoor humidity level can be maintained in the buildings throughout the year, it can significantly reduce seasonal flu transmission and save thousands of lives every year.
Solution to reduce transmission of virus related illness
The recommended guidelines laid by the government to prevent the cross transmission of the virus focuses more on direct physical contact. However, the transmission that occurs through air should be given equal importance and relevant steps must be taken in this regard as well.This responsibility ultimately falls on the building owners and operators, specially the healthcare facilities, banking structures, warehouses, quarantine centers and supermarkets which houses the most vulnerable people and are at the highest risk of contracting air-borne diseases such as coronavirus and influenza. It is these structures which carry the people on its shoulders in times of crisis like today. The shutdown of these structures due to poor IAQ would result in absolute chaos.
As a nation of a billion population, we need a contingency plan for another pandemic spread by air-borne virus. The nation’s regulatory bodies need to take adequate measures in accordance with the above mentioned studies and make it mandatory for building owners to maintain the optimum humidity level. This would not only prevent virus related illness but also ensure physical and mental wellbeing of the residents.