Coronavirus and homemade tools

[hemmjo]

"Caveat: snip...
Now my question is: - how can a naturally occurring element (7 on the periodic table), being more than 3/4 of the atmosphere, "be irritating/ harmful to your respiratory system" ?

Oxygen is also a naturally occurring element that is essential for life. Oxygen can be found alone O, combined with another O atom to make O2, or combined with 2 other O atoms to make Ozone (O3). All 3 forms are Pure Oxygen. But O3 is toxic.

Sodium and Chlorine are also VERY TOXIC to our health. But you love them on your food, as long as they are combined to make SALT