Our Project, registered under NCv2.1, incorporates newer SCAQMD VOC limits based on NCv2.2 wherever those limits are more stringent than older SCAQMD and BAAQMD Rules cited for NCv2.1. Some category definitions in South Coast and Bay Area District Rules are ambiguous. When we cannot determine which VOC limit applies, we rely on manufacturer\'s claims that South Coast and Bay Area Districts allow a product\'s sale for the intended use. However, products sold only in small containers qualify for Rule exemptions allowing use despite excess VOC\'s. LEED Reference Guide does not address exemptions. EXAMPLE: NCv2.1 and NCv2.2 require the same VOC limits for Architectural Sealant Primers, allowing much higher VOC\'s for sealant primers at "Porous" substrates. BAAQMD and SCAQMD Rules define "Porous Material" similarly, but delineate no absolute threshold between "Porous" and "Nonporous". As examples, the definitions list wood, fabric, paper, cardboard, and foam, suggesting that less absorptive materials like concrete may not qualify as "Porous". We had not anticipated that at least two of the many approved low-VOC joint sealants on our Project might require sealant primer when applied to concrete. These primers fall between the two specified VOC limits. Ambiguous definitions force us to apply the more restrictive limit, disallowing the primers in question. In response, the sealant manufacturer contends that BAAQMD permits the proposed sealant primers, so they should be acceptable under EQc4.1. However, it is unclear whether the products qualify under the less restrictive "Porous" category, or if the District allows them under the small container exemption. We fear that approving products allowed under Rule exemptions may force us to demonstrate overall low-VOC performance for the entire Project using VOC Budget calculations. The method described in the Reference Guide appears to require quantity tracking for ALL products governed by the LEED Credit in jeopardy. At this point, many months into construction, such after-the-fact quantity tracking could excessively burden the dozens of contractors and subcontractors who have used VOC-compliant adhesives and sealants in hundreds of applications. As an alternative, a VOC Budget averaging emissions ONLY of the two sealants and primers in question would demonstrate that the low-VOC sealant negates the primer (based on much higher sealant application rates). Tallying emissions for a hundred more low-VOC products becomes superfluous. We do not want to impose arbitrary restrictions or require excessive documentation simply because referenced standards are unclear. Therefore, we have the following related questions: 1. What distinguishes "Porous" from "Nonporous" under BAAQMD and SCAQMD definitions for sealant primer? [We suspect that the distinguishing characteristic may be whether the primer acts simply as a bond enhancer (at slick, Nonporous Substrates), or as a sealer as well (at Porous Substrates, to prevent migrating fluids from damaging the substrate or the seal). Designation may depend as much on primer and sealant composition as on the substrate\'s absorptiveness.] 2. Is it sufficient to demonstrate that the District whose Rule is cited in Credit requirements permits the product\'s use, or does a VOC Budget calculation become necessary to offset excess VOC\'s from products allowed under BAAQMD and SCAQMD Rule exemptions. 3. If a VOC Budget calculation becomes necessary, is it sufficient to demonstrate that low emissions from a limited number of low-VOC products offset excess emissions of a few non-compliant products, without calculating emissions for EVERY applicable product on the Project. Similar issues with ambiguities, exemptions, and VOC Budget exist in NCv2.1 and NCv2.2, Credits EQc4.1 and EQc4.2.