Air Testing and Occupancy

The LEED air testing levels are mostly based on the California Chronic Reference Exposure Levels which are for continuous indoor exposures averaged over a year for up to a lifetime.  They often apply to sensitive populations (elderly, underlying illness, very young, etc.).  They are based on health risk assessments which are often times overly conservative.  These criteria are typically one to two orders of magnitude less than occupational exposure limits (OELs) such as OSHA PELs, ACGIH TLVs, and NIOSH RELs. OELs are typically defined as representing conditions under which it is believed that nearly all workers may be repeatedly exposed, day after day, over a working lifetime, without adverse health effects.  They are averaged over 8 hours for a 40 hour work week.  For a working lifetime. Minimal exceedance (i.e., <100%) of the LEED allowable levels for the chemicals and other materials typically sampled, especially the 500 ug/M3 total VOC criteria, would typically not represent a hazardous atmosphere.  However, a professinal such as a Certified industrial Hygienist should be consulted to evaluate individual cases.  In addition, the LEED air testing criteria are not designed for measuring potential adverse human health outcomes.  They are voluntary (non-regulatory) guidelines to help determine whether excess building emissions are present.  The OELs (especially the less stringent OSHA PELs) would trigger potential regulatory or liability issues. However, if the LEED air testing showed levels within 10 times the OELs there would be something seriously wrong.  In my 37 years of experience with IAQ issues (over 20 years with LEED) the LEED Air Testing criteria are not very useful for evaluating the current or future impacts of the indoor air or its managment on occupant health.             

Hi Allison, Yes, the space should be unoccupied before all requirements are meet, except retail projects (may conduct the testing within 14 days of occupancy). 
Based on LEED guide, all measurements to conduct before occupancy but during normal occupied hours, with the building ventilation, system started at the normal daily start time and operated at the minimum outdoor airflow rate for the occupied mode throughout the test.  Best regard – Afogreen Build team