Minimizing Coronavirus Transmission through Hospital Mechanical and Plumbing Systems
The Centers for Disease Control and Prevention (CDC) recommends that patients with infectious diseases, such as novel coronavirus (COVID-19), be treated in an airborne infection (AIIR) isolation room. AIIR must meet several performance requirements.
AIIR requires at least 12 air changes per hour, all exhausted directly to the outside.
Each room is kept under negative pressure. This means that hallway air is drawn into the room and exhausted. This purpose is to protect other patients, medical staff, and basically everyone in the hospital. Generating negative pressure is very important when other buildings are used as temporary hospitals. The CDC advises that patients should not be placed in rooms where the air is recirculated without a HEPA (High-Efficiency Particulate Air) filter. Hospital emergency room waiting rooms should be evacuated directly to the outside as they may have undiagnosed patients. This minimizes the number of potentially infectious virus particles in the air.
How do hospitals manage indoor air quality?
In hospitals, a portion of the air is conditioned and recirculated throughout the facility. To protect patients and hospital residents, air handling systems rely on dilution and filtration. Dilution refers to the air exchange rate (the amount of air added or removed per unit of time). Hospitals usually have high air exchange rates to ensure a safe and hygienic environment. Hospital air handling units have final filters with a minimum reported efficiency of at least MERV 14. This filter can remove 75% of particles in the 0.3 to 1.0-micron range and 95% of larger particles.
In some cases, hospitals prefer a HEPA filter as the final filter that retains 99.97% of particles as small as 0.3 microns.
The ability of HEPA filters to trap the COVID-19 virus has been questioned as each virion is between 0.06 and 0.14 microns. However, the virus is usually shed in saliva droplets, which are larger particles. Based on this information and CDC recommendations, it is believed that HEPA filtration can help reduce the spread of coronavirus.
Remember, no single measure can stop coronavirus 100 times more effectively. However, using multiple methods in combination reduces the coronavirus transmission speed. This includes effective ventilation, social distancing, and appropriate protective equipment for medical staff.
To successfully use a HEPA filter in an HVAC, the filter must be incorporated into her HVAC installation and air handling unit.
- HEPA filters must be fitted snugly and properly, as air leaking through the edges will render them ineffective.
- The air handling unit fans must have enough power to overcome the pressure drop caused by the HEPA filter.
- Combining a HEPA filter with Germicidal Ultraviolet (UVGI) can help fight viruses and other bacteria more effectively.
Another design aspect to consider is relative humidity. Although the COVID-19 virus is a new strain, previous studies by ASHRAE and others have found that coronavirus transmission generally decreases at 40-60% relative humidity. Therefore, hospitals should monitor humidity and keep it within this range. Although specific effects of coronavirus have not yet been studied, humidity control generally helps prevent infections.
Relative humidity in a building depends on several factors. An effective building envelope that isolates indoor air from outdoor conditions, proper HVAC design, and humidifier capacity.
Hospital Plumbing Systems Design Considerations
Many disease prevention design features build on previous research by organizations such as ASHRAE. These measures have not been extensively tested against coronavirus, but they can help fight infections in general.
A World Health Organization (WHO) study shows that some infectious diseases can be spread through floor drains and similar fixtures. This occurs when a change in air pressure depletes the plumbing trap and removes the barrier between the room air and the drainage system. Plumbing codes have strict requirements for sanitary waste systems to prevent trap depletion due to pressure changes. Drains that are not used regularly can lose odor through evaporation. However, please be aware that it may cause a noticeable odor leak. A simple way to prevent evaporation in the trap is to periodically dump a gallon of water down the drain. Keep in mind that traps should be checked more often in a dry environment as they evaporate faster.
Stagnant hot water can harbor bacteria, so the hot water circulation system must be balanced to maintain flow. Frequent hand washing is only effective if the water used is sterile. Proper temperature control is also important and the water should not be overheated to avoid burns.
Be careful with coronavirus!
Now that the covid-19 pandemic has subsided and is no longer as scary as before, their symptoms still cause us many health problems later on. So the thing to do is to wear a mask continuously and go to the doctor immediately when detecting symptoms. Above are ways to minimize CoronaVirus transmission through hospital mechanical and plumbing systems.
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Prevention is better than cure, so follow the principles of disease prevention and exercise more to increase resistance, rather than spend money on medical examination in the hospital.
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