One-inch equals 2.54 centimeters (cm) so one cm equals about 0.39 of an inch.
Divide the cm by 10,000 and the result is one micron.
Dividing the micron by 1,000 yields the unit of distance known as a nanometer (nm). Divide one nm by three and you have the approximate width of an oxygen molecule (O2). In the air, the closest neighboring O2 molecule is about 4 nm away or the equivalent of about 25 feet for a human with a two-foot width. Thus, O2 maintains ample space between molecules for proper social distancing at the atomic level. O2 is just 20% of all the gases that occupy the atmosphere leaving plenty of room for nitrogen, the most prevalent component of air at 78%. The rest is carbon dioxide, water vapor, and other trace elements like argon and neon. At higher altitudes, gases like ozone, helium, and hydrogen are found. When air enters our homes and passes through a central HVAC system, the component gases are unchanged. The one exception is water vapor that condenses into liquid water as the air is cooled. We all enjoy the cooled air at lower humidity, but the true “conditioning” aspect of the HVAC system is the removal of all the other stuff that is floating around in the air. This includes polluting chemicals, pollen, dust, pet dander, mold spores, and even airborne viruses that get lifted into the atmosphere. Removing these substances is left to the humble filter that is so often ignored but is the most important component in cleaning the air so we can breathe in and extract the life-giving O2. This is why HVAC professionals are constantly reminding homeowners to change their filters regularly in between regularly scheduled service calls.