why living in a building is more dangerous

You are confined in a quiet house in the countryside? So much the better. Because residents living in tall buildings may have worry to be done, according to the Institute for the Design of Sustainable Buildings at Heriot-Watt University. The coronavirus would indeed be likely to spread via the sewersinfecting not only Ambiant air but can also deposit contaminated droplets on surfaces.

In 2003 Michael Gormley and his colleagues conducted a study during the SARS epidemic in Hong Kong, in a 33- to 41-story building complex called Amoy Garden, health home to 19,000 residents. A foyer particularly severe infection, since more than 300 cases of SARS and 42 deaths had been confirmed there, or about one-sixth of the total number of cases and deaths from SARS on the island as a whole, reported a study published in the Journal of The Royal Society of Medicine at the time. The guilty ? The piping system, which served to spread the virus in the apartments.

Dry siphons during confinement

In this residence, as in most large high-rise buildings, the toilets are smart health connected to a U-shaped siphon, which in particular prevents reflux of bad odors. Normally, the siphon is always filled with water, which prevents theair to go back up there. Except that during a period of confinement, the siphons tend to be dry, mainly due to the pressure additional generated by the simultaneous use of many people trapped in their homes, or on the contrary when the toilets remain unused for a long time with absent residents.

In another study published in 2017 in the journal Plos One, Michael Gormley's team modeled the way agents pathogens contained in excrement can spread asaerosols and be transported by air via dry sewers. The researchers reproduced a plumbing system representing two floors of a building. They then introduced fecal bacteria in the water before flushing, then measured the amount of pathogens in the air and in the water on the top floor. Result: " The debits air typical of a sanitary plumbing system (between 20 and 30 liters per second) is sufficient to transport pathogens in aerosol between the different floors of a building Says the study. Not only the bacteria diffuse into the air as droplets, but the latter can also be redeployed on all surfaces, thus contaminating the entire room.

The risk is all the greater as gastrointestinal disorders and diarrhea are part of symptoms currents of Covid-19. However, a recent study has just shown that the virus could be transmitted through the faeces, the feces of patients with diarrhea being very loaded with viral particles. " As has happened at Amoy Gardens, a high concentration of people infected with diarrhea can contribute to a viral load higher ", says Michael Gormley. " And since all apartments are interconnected by the sewer system, the plumbing can even facilitate infection between buildings close to each other. "

Toilets: the rules to follow to avoid contamination

In the review The Lancet, the researcher therefore recommends a few rules to prevent this risk.

• Do not ignore bad smells in bathrooms, kitchens or toilets, a sign that the siphon may be empty.
• Check the condition of the siphon and its proper functioning.
• Run the water in all sinks and the WC for at least five seconds in the morning and in the evening, especially in damp rooms.
• If there appears to be a crack or a leak in the piping, immediately plug it with a bag plastic and tape using gloves while rubber.

Also remember another basic hygiene rule: close the toilet lid when flushing, so as not to spread contaminated droplets in the room.