Fundamentally, clean water has proven to be a tremendous win in the history of improving the well being of almost all people globally.  Clean food - pasteurization and refrigeration, understanding of food born illness - has also proven to similarly be tremendously useful.  Clean air is the next big thing on the list, essentially.

Vaccines are great but they are kind of slow to respond, and kind of expensive, and not everyone is able or willing to use them.  "Engineering controls" - like sanitation systems for water born illness -  form a reliable, durable baseline that protects absolutely everyone.  They can dampen or nix the next pandemic before it even starts. 

And they can be unbelievably cheap for what we get when we do it large scale.  Compared to the cost of a road that passes by a building, making sure the air in any given building is clean is incredibly cheap.  We can do roads, and we can do this.

Our health is affected considerably adversely by pathogens obviously, but also to a lesser degree in many ways it is harmed by particulate pollution (which includes allergens), mycotoxins (which are gasses usually), VOCs, CO2 and even water vapor when present to excess degree.  It's also true that some components released by plants have shown to be beneficial, so air is quite complex.  Fundamentally, it's a nearly directly connection to the contents of our bloodstream - even some particles can get through the membranes in our lungs and get into our bodies, notably 2.5 micron and thereabouts sized particles (PM2.5).  Certainly many gasses, including mycotoxins, VOCs and CO2 just get right in there, whatever is in the air we breathe shows up to comparable degree in our blood.  Not good, boss.

The airborne route is by far the most fearsome and effective way for a virus to propagate in the modern world.  We already have one pandemic that devastated the world and economy, and another one with H5N1 is very much brewing.  We need to take action now.

Household filtration is not enough. Schools, offices and frankly everywhere people are breathing air that others may have breathed recently, need explicit measures to improve the cleanliness of air, or the next pandemic could be even worse than this current one.

Here are a few resources to find out more:

https://letsair.org/