How disease breaks into hotel rooms
The Insight
The spread of COVID-19 within hotel quarantine facilities has gained considerable public attention lately. The COVID-19 virus is highly contagious as it spreads via moisture droplets that are generally expired from the host's respiratory system.
The general consensus is that the hotels being used as quarantine facilities where COVID-19 has spread were never designed for disease containment. However, are the air-conditioning and ventilation systems in any hotel designed to prevent the spread of disease?
The short answer is no – they are not.
To do so would amount to significant additional costs to the building owner and the operators.
The Impact
Hotels generally have individual air-conditioning systems serving each room with common ventilation systems. Exhaust ventilation and outdoor air ventilation are generally provided via common risers.
Within health facilities, disease isolation rooms are designed to prevent the spread of disease through negative pressure controls that prevent air from travelling from the isolation room to other parts of the facility. High-efficiency filtration is also often applied to airflow entering the room.
Hotels, on the other hand, are generally positively pressurised to prevent infiltration of unconditioned outdoor air. This is done to decrease air-conditioning and/or heating loads. The outdoor air is often introduced to the adjoining corridor where it is mixed with the corridor air before entering the respective space. Exhaust air ventilation is generally drawn from the amenities with minimal controls in place to prevent the mixing and recirculation of exhaust air from the individual suites.
Additionally, when the air is humid and close to saturation, there is little opportunity for moisture droplets from the expired breath of the host to be entrained into the air. When the air is dry, moisture particles can easily be entrained from the expired breath, allowing the disease to spread more easily. Humidity is generally removed from hotel facilities via the air conditioning system, as it can lead to issues with mould and mildew.
These design strategies within hotel facilities have permitted the spread of air-borne and droplet-borne disease.