Science of coughing and sneezing

Like humans, coughs are also in shape and size. It can be shallow or deep, short or long. Scientists studying our coughing and sneezing ways have shed light on the path of viral transmission such as influenza viruses.

Cough and sneeze spread bacteria farther than we thought

For flu and common colds, health workers say the best way to prevent the spread of the virus is to wash your hands and cover your mouth when you cough or sneeze.

Cough

Following the development of coughing, scientists use meticulous settings to reveal the amount of saliva being pushed out and where it floats.

They asked participants to cough into the masks, then carefully determine the weight of the mask before and after coughing. They also illustrated the cough image with sophisticated imaging and laser techniques, then used computers to visualize the movement of thousands of small molecules. The scientists also used heated human body models and cough machines in the room filled with small drops of olive oil or stage smoke to track the air's movement, where it dispersed, and the extent Our exposure to other people's coughs.

Picture when a healthy person coughs.Each coughing sound contains droplets, if sick, those droplets will carry the virus.(Photo: Gary S. Settles / Penn University)

The usual cough usually starts with a deep breath, then the air is compressed in the lungs and pushed out in just a few seconds.

The usual human cough can fill 3/4 of a 2-liter soda bottle but filled with air. Air flows out of the lungs in the form of rays that extend several feet long. Cough also pushes out thousands of small saliva drops. About 3,000 droplets were ejected during a cough, some drops flew out of the mouth at speeds of up to 50 miles per hour.

Sneeze

Sneezing is even worse than coughing. It started at the throat and pushed out smaller droplets - up to 40,000 drops - some shot out at jet speed, over 200 miles per hour. Most droplets are less than 100 microns in diameter - only the thickness of a human hair. Many drops are so small that they cannot be observed with the naked eye.

"What happens with these droplets depends on their size, " said fluid dynamics researcher Bakhtier Farouk of Drexel University in Philadelphia. Bakhtier Farouk is currently studying software that simulates microscopic droplets moving around the room.

A photo of a person when you sneeze while you're watching is not a joke.It reveals images of saliva and long enough to stay on the doorknob or hovering to infect others.Images illustrate why you should cover your mouth when sneezing or coughing to protect others from contact with bacteria.That is why you need to wash your hands often when others do not often cover their mouths when sneezing.(Photo: CDC / James Gathany)

Most heavier and larger droplets fall to the floor quickly under the influence of gravity . Smaller and lighter droplets (less than 5 microns in diameter) are less susceptible to gravity, so they can remain in an airborne state almost indefinitely because they are pushed and dispersed by air currents. in room.

Movement in the room can also cause heavier droplets to return to the suspended state after they have fallen to the ground or other surfaces. Removing a bed in a hospital can also throw viruses on the bed surface. Opening the door of the room quickly changed the air flow in the room, following the virus on the floor. Even passing through the room can spread saliva.

If we are sick, the droplets in a cough can contain up to two hundred million individual virus molecules. This number varies considerably according to the process of infection because the immune system can kill the virus. In general, sick people are most likely to spread the disease to other people as soon as the first symptoms appear, and the most difficult to spread when their immune system is able to kill the virus.

Hovering in the air and getting ready to infect

Once in the air, the virus that exists in the droplets can live for several hours. Even if the droplets touch a surface, the virus persists and can still spread the disease if the droplets return to the air. When the saliva touches the paper, its virus particles can last for several hours. On steel or plastic, the virus can last for many days.

When we inhale, the droplets will cling to the cells in the throat where the virus will enter these cells and start dividing. This may or may not cause illness. According to Julian Tang, a virus researcher in Singapore, the body's natural defense barrier is designed to eliminate infection; Whether we are sick or not depends on the amount of virus that we breathe in and whether our immune system has ever encountered this virus before.

When we are sick, our bodies begin to deal with infection by producing mucus to eliminate the virus. Part of the mucus is swallowed by the neck to carry the virus down to the stomach and decompose the acid there. Some viruses in the throat will be pushed out when we cough. The cough then pushed out the new mucus and virus, thus starting a new infection cycle.