As many of us gather indoors for dinner and drinks while on vacation, we need to think about ventilation to minimize the spread of COVID-19.
SARS-CoV-2, the virus that causes COVID, is spread primarily through larger particles called droplets, but also through smaller particles called aerosols and by touching contaminated surfaces.
Aerosol particles are lighter than droplet size particles and can be suspended in the air longer. The suspension and therefore the transmission of aerosols is facilitated by poor ventilation.
Increasing ventilation indoors, with fresh air outdoors, is a key method of dispersing virus particles. Ventilation can reduce the risk that a single COVID-positive person (who does not yet know they are contagious) will infect other people.
There are some simple steps you can take at home and at work to improve ventilation during the Christmas season and beyond.
Open doors and windows
The best strategy at home and at work is to simply open doors and windows.
If you have friends and family for dinner or your office Christmas party, consider moving tables and chairs closer to open windows and opening a door to create a gentle breeze.
Adjust the air conditioner to bring in fresh air from outside.
Air conditioners can help, but they need to be configured correctly.
At work or at home, you don’t want to recirculate indoor air because you are only venting the same air into the room (but now cooler or warmer).
Instead, always make sure your air conditioner is set to bring in 100% fresh air from outside. There are office environments that allow the system to increase air exchange per hour, which means it can reduce the time it takes to completely replace all the air inside the room with air. fresh air from outside.
Air conditioners can help ventilate rooms, but only if they bring in fresh air from the outside, rather than recirculating the indoor air.
Air conditioners can help ventilate rooms, but only if they bring in fresh air from the outside, rather than recirculating the indoor air. Shutterstock
But the direction of the airflow is also important. For example, airflow from an air conditioner (which recirculated the air rather than carrying it outside) has been implicated in the spread of the virus to several dinners at restaurant tables in China.
Offices that accommodate staff should prime their air conditioners by having their technicians help the system draw in fresh air faster than the pre-COVID setting (which could be around 40 liters per second per person) at not less than 60 liters per second, per person.
In hospitals, nursing homes, and quarantines in hotels, qualified engineers should be involved to assess the adequacy of air conditioning flow. This is especially important for all “hotspots” that host people who are COVID positive.
The World Health Organization recommends that hot spots make 12 airflow changes per hour (that’s 80 liters per second per person), which means the air has replaced a total of 12 times every 60 minutes. This is the gold standard for ventilation and can be very difficult to achieve in many buildings.
The competition guide published by the US Centers for Disease Control and Prevention last week recommends placing fans near open windows to improve airflow. It is always recommended to keep the fans in case the room is occupied, for example in restaurants.
As with air conditioning, fans can be dangerous if they push the air directly from person to person, and one of them is contagious. The fan should be positioned so that it increases the flow of fresh air into the room and not so that the air moves from the room to the open window or door.
Don’t worry about HEPA filters at home
High-Efficiency Particulate Filters (HEPA) have been marketed as a way to reduce the concentration of SARS-CoV-2 particles in the air.
Its effectiveness depends on the airflow capacity of the unit, the configuration of the room, the number of people in the room, and the location of the filter in the room.
But there is no evidence to suggest that a portable HEPA filter will help you in your home. So don’t rush to buy one for Christmas.
It can be effective in some areas of health care, such as the COVID ward in a hospital or nursing home, especially when used in negative pressure rooms. The combination of a HEPA filter and negative air pressure reduces the risk of aerosol particles escaping in the passage.
In public transport, taxis, and works
COVID outbreaks were monitored for public transport exposures. For example, a young man traveled to Hunan Province, China on two buses and injured several people who were sitting in different areas of the buses. Chinese researchers conducted a study on this mass, which developed the theory of airflow:
Closed windows with active ventilation in buses would have created an ideal environment for the transport of aerosols […] The vents were lined up above the windows on both sides and the exhaust fan was in the front, which it could cause an airflow that carries aerosols containing the viral particles from the rear to the center and from the front of the car.
The study authors recommend opening all windows to public transportation to help disperse the viral particles. If you are on a tram or bus, you should open them if you can.
However, this may be impossible on some forms of public transport, such as trains. In these cases, you have to wear a mask.
Likewise, it is ideal that the windows are closed in taxis and taxis. But if you can’t or don’t want to, turn on the air conditioner and let fresh air outside. And I’m still wearing a mask!