The proposed section 16VAC25-220-50 references ANSI/ASHRAE Standards 62.1 and 62.2 (2019a, 2019b).  However, the Virginia USBC utilizes the 2015 International Mechanical Code, which references ASHRAE 62.1-2013, which is two versions behind (i.e., 2016 and 2019).  So buildings currently under design would likely not fully comply with the referenced 2019 standard.  Older buildings designs may not be close to current building designs and equipment may not be capable of achieving the proposed standard.

Note that "'Economic feasibility' means the employer is financially able to undertake the measures necessary to comply with one or more requirements in this standard.  The cost of corrective measures to be taken will not usually be considered as a factor in determining whether a violation of this standard has occurred.  If an employer's level of compliance lags significantly behand of its industry, an employer's claim of economic infeasibility will not be accepted."  The term "industry" is undefined and is thus subject to varying interpretations and enforcements.  E.g., consider two private schools, one with 600 students and a $10M endowment and one with 125 students and no endowment.  Are they to be treated same because they are both in the private education "industry"?

Note that "Building or facility owner" is defined as "the legal entity, including a lessee, that exercises control over management and record keeping functions relating to a building or facility in which activities covered by this standard take place."  While the actual building owner might generally maintain and exercise such control, in a pre-existing lease, a lessee may have accepted such responsibility in exchange for a lower rent.  Clearly, at the time of entering into the lease pre-Covid, the lessee had no reason to believe that it would face the types of obligations that would be imposed by this proposed standard, which could result in financial ruin for a small business.

Outdoor air dilution is one aspect that is addressed in the proposed standard.  However, did not see where filtration improvements (MERV 13 seems to be minimum industry recommendation) or UV lights in air-handling systems are addressed.

There are vague references to "maintaining equipment."  If one is to demonstrate compliance with ASHRAE 62.1, that would require an engineering analysis and an air balance.