Both seem to be predicated on the assumption that, in each case, the bar is a low one and fundamentally it is the ventilation systems, their poor practice and maintenance that is to blame. This I believe is doing a whole section of building, estates and facilities management professionals a gross disservice.
I absolutely agree that there are set ups that can aid the objective of further improving outside air ventilation. But in many instances, the historic cries of SBS were more directly attributable to a specific failure in part of the system or its maintenance/management, and these were actually the exceptions as opposed to the rule.
We have been monitoring air quality for over 35 years and have data amounting to literally millions of physicals tests, examinations and checks that have been carried out over this time, much of which is UKAS accredited. Overwhelmingly we are able to demonstrate IAQ, in terms of dust levels, microorganisms and gas levels (both Carbon dioxide and a range of pollutants), to be very good and almost exclusively improved over that of the outside air being drawn into the building.
I also use the word “outside” air over that of “fresh” purposely, as the inference being made in using the latter is that it is better/cleaner. Anyone having done any form of meaningful testing in urban environments will know it most certainly isn’t. For those with well managed, well maintained and regularly assessed buildings, that the air quality has on the whole been very good, if not excellent for the occupants (in comparison to the “fresh” air outside), the issue is the occupants were rarely aware of it.
Perhaps now is the time for the industry to keep shouting about all the good work it does that often otherwise goes unrecognised.
So, before you start investing in solutions and equipment to improve your IAQ and ventilation, perhaps knowing your baseline would be a good first step. You can then assess with confidence based on facts, not supposition what, if any, action is needed and how beneficial if at all, any changes will be.