Air purification implementation

There are two questions here - first, whether there's a LEED credit that addresses purification units, and second whether stand-alone units would comply. I don't think the current BD&C credits address purification specifically, but purification equipment might help meet the one-time IAQ testing for EQc4 Indoor Air Quality Assessment Option 2, Testing.  There is a pilot credit called "Performance-based indoor air quality design and assessment" that relies on air quality monitoring & testing, so purification equipment could play a role in maintaining good IAQ for pursuing that pilot credit.   In general, if there's a portable "appliance" used to meet a credit requirement it can be hard to make the case the units will be provided and operated for the long term. If you can get something added to a lease agreement, which is a legally binding aggreement, you might be able to convince a reviewer something will be be provided for the long-term.  Hope that helps answer your questions.