If you wish to pass on the science, go to the last paragraph titled The Bottom Line for recommendations.
Taxonomy, Genomic Structure and Morphology
This particular virus, Covid-19, is between 100 and 120 nano-meters in diameter. A micron is one millionth of a meter. A nano-meter is one thousandth of a micron.
Coronaviruses have extraordinarily large single-stranded RNA genomes – approximately 26,000 to 32,000 bases or RNA “letters” in length. Coronavirus particles are surrounded by a fatty outer layer called an envelope and usually appear spherical, as seen under an electron microscope, with a crown or “corona” of club-shaped spikes on their surface. [source]
There is speculation the virus was developed in a Chinese laboratory in Wuhan, China. Whether it was developed in a lab or in the wild, it is zoonotic, originating in a specific species of bat native to China.
#1 The natural defense common to all mankind is mucus, a natural prophylactic coating excreted by the lungs, the stomach, the intestines, the mouth (saliva), the eyes (tears) and the sinus (snot).
The CDC says, “Keeping hands clean is one of the most important steps we can take to avoid getting sick and spreading germs to others. Many diseases and conditions are spread by not washing hands with soap and clean, running water.“
The CDC prescribes either hand washing with soap and water or using a hand sanitizer. The chief difference: hand washing with soap (actually detergent) and water removes germs; alcohol-based sanitizers kill about 60% of germs on the hands. Soap and water remove germs; sanitizers kill most germs. Best is soap and water. Second-best is sanitizers.
Not all hand sanitizers are equal. When using hand sanitizers don’t wipe them dry. Allow the alcohol to dry through evaporation. Drying removes the alcohol thereby limiting the effectiveness of the hand cleaner.
Alcohol-based hand sanitizers can quickly reduce the number of microbes on hands in some situations, but sanitizers do not eliminate all types of germs.
#3 Antibodies are a natural defense developed in one of two ways. Either exposure to a germ or a vaccination against the germ will create defensive antibodies.
#4 Face masks – how and why are they effective in stopping the spread of the disease, if they are effective?
Recent news stories reveal a hodgepodge of rules against wearing personal protection equipment (PPE) brought into a hospital by a medical professional based on claims wearing masks frightens patients or one employee wearing a mask may upset other employees who, due to a shortage of PPE feel shortchanged, or claims the PPE brought into a hospital may not be sterile. For more, read the NPR article published April 2, 2020: Doctors Say Hospitals Are Stopping Them From Wearing Masks.
With respect to preventing the spread of the virus via droplets from a wearer of masks is a certainty, wearing a mask to prevent exposure to the airborne virus is questionable.
Why – how – are the Japanese able to go about their daily lives, working, enjoying the great outdoors, shopping, and celebrating cherry blossoms? Are the masks the answer? Probably not.
The chief reason the Japanese are weathering the Covid-19 storm better than most other countries is hygienic practices. Read from Tokyo Creative, HYGIENE PRACTICES IN JAPAN.
With respect to face masks as PPE, a little science goes a long way. N95 masks: the N means “not oil resistant”. The 95 means “removes 95% of all particles that are at least 0.3 microns in diameter”.
How does a .3 micron filter capture a coronavirus between 100 and 120 nano-meters in diameter? The virus does not suspend in air itself. The virus rides droplets of excretions from infected people who do not cover their mouths and noses when coughing or sneezing. The NCBI article Natural Ventilation for Infection Control in Health-Care Settings describes the behavior and composition of droplets excreted by humans. Big droplets fall to the floor; small droplets go for a ride.
In summary, N95 face masks are effective in arresting airborne viruses riding on droplets, keeping them from entering your airways. The big caution is this is only true if the mask has a good seal against the face.
A WORD OF CAUTION – Those inexpensive dust masks you purchase from hardware stores like Home Depot provide no personal protection. They can, however, be helpful to prevent the transmission of the virus from the wearer of the dust masks to other persons. My opinion: inexpensive dust masks give the wearers a false sense of security.
The Unspoken Word: Ventilation
According to the CDC, “On any given day, about one in 31 hospital patients has at least one healthcare-associated infection.”
Healthcare-associated infection infections are caused by viral, bacterial, and fungal pathogens; the most common types are bloodstream infection (BSI), pneumonia (eg, ventilator-associated pneumonia [VAP]), urinary tract infection (UTI), and surgical site infection (SSI). [Source]
How do hospitals mitigate HAI? One method is ventilation, replacing contaminated inside air with fresh air and controlling the flow of air within the conditioned space so as to not disperse infectious droplets that can be inhaled by either medical personnel or visitors in the conditioned space.
All the above is said to make clear that outdoors you are least exposed to airborne viruses riding comfortably along on the droplets excreted by persons carrying the COVID-19 virus. You are at an exponentially greater risk of becoming infected in an indoor space.
At the present time, the CDC identifies the ten leading causes of death and Covid-19 is not on the list.
The annual influenza, A and B, ranks as the eighth leading cause of death, followed by suicide which is the tenth.
The Bottom Line
Wear appropriate medical-grade masks to prevent the infection of others by you and to reduce the likelihood of infecting yourself or others nearby. Lacking access to medical-grade masks, purchase inexpensive face masks like the Walmart Equate Earloop Disposable Facemasks. If you can’t purchase facemasks, someone with sewing know-how can make a reusable mask for you.