LEED Zone

Many building products used indoors contain organic chemicals that can vaporize and cause contamination of indoor air. As a result, building occupants are subjected to inhalation exposures. These volatile organic compounds (VOCs) are present in products as residual solvents, chemical reaction or dissociation products, purposefully introduced additives, and manufacturing contaminants. The emission testing process measures the rate of the release of those VOCs to indoor air.

VOCs of potential concern include:
• Formaldehyde
• Chronic systemic toxins such as toluene, styrene, phenol, and naphthalene
• Carcinogens, mutagens, and teratogens as defined by the International Agency for Research on Cancer, the National Toxicology Program Report on Carcinogens, and CA Proposition 65
• Sensory irritants
• Odorants
VOCs contained in dry products diffuse through the material and partition to air at the material surface. The rate of release to air, termed emission rate, is determined by the concentration of the VOC in the material, the rate of its diffusion in the material, and its partitioning coefficient between the material and air. Each chemical and material combination has a characteristic release rate.
 

VOC emission testing consists in placing the product sample an environmental chamber under controlled temperature and relative humidity and operated with a constant flow of clean air. As VOCs are released, the concentrations of VOCs in chamber air increase. Once a steady state is achieved, the air samples are collected and analyzed. A steady-state VOC emission rate at a given time point (typically in micrograms of VOC per square meter of material per hour) is calculated as the product of the chamber air concentration and the inlet air flow rate divided by the area of the emitting product surface. Those emission rates are then used to evaluate the concentrations in buildings, which then can be compared to inhalation exposure guidelines.
(Source Berkeley Analytical)