“Everyone I interviewed for this article has observed that keeping 6 feet from others is definitely a challenge.” Now I don’t feel so bad. The best tips I have ever seen on this Very Important Topic! 4 minute Video
Humans are social animals. We crave getting close together. Overcoming habits you’ve always done since you were a child is very difficult.
This analysis has some of the best illustrations I have seen, using a living room, a bar, and a classroom.
One time examples, such as the church choir in Seattle or infections in bars, are useful. But we are a visual species. Illustrations and animations can help understand what is happening.
Spanish paper El Pais ran various simulations using the Covid Airborne Transmission Estimator developed by scientists from the University of Colorado. Excellent Illustrations of Covid spreading indoors.
A few excerpts: Irrespective of whether safe distances are maintained, if the six people spend four hours together talking loudly, without wearing a face mask in a room with no ventilation, five will become infected, according to the scientific model explained in the methodology.
The infection risk drops to below one when the group uses face masks, shortens the length of the gathering by half, and ventilates the space used.
If two hours are spent in the classroom with an infected teacher and 20 students, without taking any measures to counter the number of aerosols, there is the risk that up to 12 students could become infected.
To watch the Excellent Illustrations of Covid spreading indoors, translated into English, click here.
The Centers for Disease Control and Prevention has new guidance clarifying what exactly “close contact” means when it comes to transmission of SARS-Cov-2, the virus that causes COVID-19.
The previous guidance suggested that a close contact occurred when a person was within six feet of an infectious individual for 15 consecutive minutes. The New CDC guidance on 15 minutes of COVID exposure acknowledges that even brief contact can lead to transmission.
Specifically, the new guidance suggests that those spending a total of 15 minutes of contact with an infectious person throughout a 24-hour period should be considered in close contact.
Despite the change, most public health professionals have been clear for months that there is nothing magic about six feet. In the same way, there is nothing magic about 15 minutes. These should be used as rough estimates to indicate the types of contact that are relatively higher risk.
October 30, 2020, CDC report, COVID-19 in a Correctional Facility Employee Following Multiple Brief Exposures to Persons with COVID-19 — Vermont, July–August 2020Click here to read the report Note: the report can be difficult to read but worthwhile. Paragraphs are too long with too much information.
We know now that airborne small particles are emitted whenever we breathe, speak, etc. We don’t have much data about how much, if any, Covid viruses are included in the airborne particles. There are many factors: outside vs. inside, crowded small rooms, etc. We know that measles can travel through the air (distances vary) and particles can remain in the air for several hours or longer.
Studies regularly cited are observational (for example, choir practice in a small room and many were infected) or airflow patterns in research labs. Fluid dynamic studies spraying particles to see how far they go. But there is no information about how far viruses can travel in the air. An air sampling study published in late July in hospitals found that Covid was in the air particles in nearby rooms. In hospitals, Covid travels through the air, but the people are very sick and exhaling a lot of air.
The WHO’s original three-foot guideline followed some of the earliest research into how diseases spread. In the 1930s, Harvard researcher William F. Wells measured how far large exhaled droplets traveled and arrived at the three-feet figure. Click the Continue reading link below for more information on the new research study and an excellent Risk Table.
Note from all the experts: We don’t know much yet about how the virus is transmitted.
Podcast (16 minutes) “Open the Window: Talking about Airborne Transmission”
“Can the novel coronavirus be spread through the air? And if so, what can we do to make sure the air inside our homes and buildings is as clean as possible? Dr. Sanjay Gupta talks with Joseph Allen, Director of the Healthy Buildings program at the Harvard T.H. Chan School of Public Health, about the science behind airborne transmission.”
A very good, understandable and interesting, discussion by an expert from many angles, focusing on homes. But also discusses schools. Starts with tenement housing many years ago, which often lacked windows, and what was done to provide windows. I see many older apartment buildings, pre-1940, built with small “air vents” in the middle of the building providing ventilation.
On CNN Fact vs. Fiction with Dr. Sanjay Gupta. One of my favorite Covid podcasts. To listen to the Podcast Click here