Option 2 IAQ Testing

There are guidelines in the reference guide. Page 689:
STEP 1. DETERMINE AIR-TESTING LOCATIONS
Select testing locations with the least ventilation but the greatest concentration of Vocs and other 
contaminants. testing must be completed by an appropriately accredited professional. use current 
versions of astM or iso methods. the number of testing locations depends on the size of the building 
and number of ventilation systems but must include all occupied spaces. if sampling is used, all space 
types must be represented (e.g., office and classroom). use the following methodology to determine how 
many air testing locations are required.
 · test at least one location per ventilation system for each occupied space type. there must be a 
minimum of one test per floor. the locations selected for testing must represent the worst-case zones 
where the highest concentrations of contaminants of concern are likely to occur.
 · for offices, retail, schools, hospitality, and multifamily residential projects, test areas no larger than 
5,000 square feet (465 square meters). for warehouses or large open spaces in other building types 
(e.g., ballrooms in hospitality, gymnasiums in schools), a limit of 50,000 square feet (4 654 square 
meters) may be used. if there is evidence that the air in the space is well mixed and sources of 
contaminants of concern are uniform, project teams may test a single location in that space.
 · Determine whether the project includes spaces (e.g., offices, school classrooms, or multifamily 
residential units) that are identical in their construction, finishes, configuration, square footage, and 
hVac systems. Project teams may sample identical spaces by testing one in seven. if the sampled 
space fails the test, all seven must be tested.

In addition to above guidance, there is a LEED Addenda ID#100002233 air testing guidance (link below), which provides a bit more detailed information. 

https://www.usgbc.org/leedaddenda/100002233