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How do ventilation systems help or hurt us when it comes to COVID-19?

Researchers looked into the impact of ventilation systems

DETROIT – As children return to indoor classrooms and colder weather increases indoor activities for everyone, research into the way ventilation systems can help or hurt us when it comes to coronavirus (COVID-19) is important.

Researchers at the University of Cambridge in the U.K. published a study in the Journal of fluid Mechanics looking at the effects of ventilation on the indoor spread of coronavirus. They concluded that many modern office buildings may increase the risk of exposure to COVID-19.

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Evidence has increasingly shown that coronavirus is spread through larger droplets and tiny aerosols that are expelled when we breathe, talk, laugh, cough or sneeze. The smallest aerosols can remain suspended in the air and travel significant distances indoors.

Many indoor heating and cooling systems have been designed to maximize energy efficiency, leading to a decreased exchange with fresh outdoor air. The very design of many ventilation systems can also contribute to contaminated aerosols staying in a room.

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Often in an office, both the air inlets and vents are at ceiling level, this mixes the air in a room but doesn’t necessarily remove aerosols -- causing longer exposure times.

The way most homes in the U.S. with central air are designed are more likely to extract contaminated aerosols because it takes advantage of the fact that much of our breath, which is warmer than room temperature, will rise and be removed from the room.

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Whenever possible, bringing in fresh outdoor air is the quickest way to reduce the concentration of any aerosols. The researchers actually did a much more detailed analysis. They looked at the effect of opening and closing doors, and even the amount of air movement caused by the wake we leave behind when we walk through a space.

The bottom line is that keeping windows open and wearing a mask was their best advice. If you’re in an office and have access to a window, open it, or at least crack it to allow fresh air in.

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