Interesting study out of Harvard: worker productivity, and cognition levels, are influenced by indoor air quality.
The double blind study had office workers do their normal jobs, but in a facility that could be controlled. The focus was on increasing ventilation, to remove VOCs and other pollutants (and likely increase oxygen content). Seems that productivity can be significantly enhanced at an annual cost of $40.00 per employee (much less with energy efficient systems), in increased heating and cooling costs associated with more airflow from the exterior. Makes sense, and looks like a good investment.
A few things one can do, ongoing, in addition to better ventilation: thorough vacuuming with HEPA filtered machines; dust wiping to remove, not just move around, small particles; microfiber wipes and mops; and careful chemical selection - all part of our standard commercial janitorial package. Touch point sanitation, not just "cleaning", helps as well. Again, very little cost provides significant results, in worker productivity, reduction in absenteeism, and so on.