A discussion we have not had: The ventilation of business premises in the era of covid-19

One thing that, in my opinion, has not been discussed regarding the safety of business premises during coronavirus pandemic, is the filtering of their air.
While various publications can now prove with certainty that covid19 is a virus mainly transmitted by airborne droplets, disproportionately little (if any) discussion is being made about how it can be treated in the professional field. And it is striking that the debate is only about compensating for the lost income of professionals but nothing is suggested to improve the ventilation of their premises, so that they can better cope with the new reality, as shaped by the pandemic.
Many dentists in the UK — I guess in other countries — have bought air-filtering machines that provide guaranteed protection against coronaviruses (and viruses and germs in general) by effectively filtering and ionizing clinics. These machines are NHS approved and cost around £ 900 per unit. They are portable and cover about 25sqm each.
The question is, since these machines are considered safe for medical facilities, why not use them in others? Maybe not e.g for cafes, but from the vast majority of small businesses and shops who are either considered of high risk (e.g barbershops) or are carried away by the general ban: most are spaces of 55–80sqm. This means that with 2, 3 or 4 such units per premise, these spaces could be covered.
Don’t get me wrong here. Such a solution is obviously not 100% effective and has its pre-conditions. But if a practice can reduce the risk, if there is a way to greatly reduce the viral load indoors, then a combination of measures can work as a medium-term solution. With a mask, with a limited number of customers and such machines many of the shops (especially the smaller ones: manicures, gift shops, bookstores, barbershops, small cafes maybe, etc.) could remain open and mitigate the financial impact.
But it is not just these machines. There are also the existing air conditioners, the ones that recycle the air inside the space, without outdoor units. These should be replaced where possible, as they exacerbate the problem of proper ventilation, especially in offices, where the installation of large units with special filters is not possible. This is an issue that should have worried countries such as Greece since last year. Although it is well known that large companies have already done so, no one seems to suggest a more general application.
One can add to this the experience of the recent past, even from something harmful such as smoking indoors. We know that strong ventilation systems had improved air quality and we may need to restore these systems, not just for the current situation. If these systems existed today, perhaps a piece of the hospitality sector could have stayed open. Of course, we can not cry over spilled milk and old decisions (which were certainly well made), but we can learn from them: why should an old tried and tested idea not apply today? Some sites still have such systems. Why should these sites be considered the same as those that do not have ventilation at all, or why they can not upgrade their systems and operate, if this can be effective?
Seeing that many scientists already predict that we should learn to live with similar pandemics in the future we are obliged to look ahead and explore possible solutions.
Funding could come from government support package through interest-free bank loans exclusively for the installation of such units. The state and the professional could contribute with a share of expenditure which may be tax deductible. That is, a form of lending that has been used before, for example for the energy upgrade of homes.
Of course all of the above is just an idea. I do not have the expertise, nor do I intend to replace the experts who can explain why such an idea may be wrong, or may indeed have practical application in the treatment of coronavirus in business premises.
But the issue is different.
Why is this not being discussed? Why a year on with a pandemic we just stick with the mask, the sanitizers and the business closure and do not go one step further, to talk about the improvement of professional premises?

If — as it already seems — covid19 came here to stay and become seasonal, the debate should no longer be whether the business will be closed every time a new outburst occurs, but by what means and in what way as safely as possible will we continue to operate despite the coronavirus.