Volatile organic compounds (VOCs) are a particular concern in indoor environments, where they can impact indoor air quality (IAQ) and lead to short- and long-term adverse health effects such as eye, nose, and throat irritation; headaches; nausea; and damage to the liver, kidneys, and central nervous system. While concentrations of VOCs are consistently higher indoors, they also are a concern outdoors. Once in the atmosphere, they react with oxygen to produce ozone, a key component of smog.

VOCs from paints, coatings, and other construction materials can be a nuisance to painting crews, building occupants, and passersby, and lead to the same potential health effects as with indoor environments. Moreover, VOCs from outside can be drawn into a building through open windows and into air systems inside of a building.

Solvent-Based Coatings and VOCs

Virtually everything that is not the dried, solid coating in a typical paint formulation is released into the air. VOCs in solventborne coatings usually come from the solvents themselves. Solvents act as carriers for the coating’s pigment and resins, helping the coating to wet out on the surface and then dry after it is applied. Once the coating is applied to a surface, the solvent evaporates, leaving the solids content in a dried-film formation on the substrate.

In general, solvents offer an efficient and low-cost means for dissolving and dispersing raw material components, and they evaporate rapidly, shortening dry times and allowing coatings contractors to be more productive. Solvent-based formulations have an inherently low surface tension and will wet out on a multitude of substrates without the use of additives. They help a coating adhere well to substrates that have less than pristine surface cleanliness.

Water can replace solvents in coatings to reduce emissions and VOCs, but these coatings generally still contain a small percentage of cosolvent to help the process. APV’s chemists who formulate water-based NeverFade^® coatings understand the characteristics of the polymer chemistry, impact of rheology modifiers, and appropriate cosolvents to optimize a continuous film formation without the need for solvents.

The VOCs in a water-based coating are usually found in the resin or binders, thickeners, certain additives such as defoamers and surfactants, and pigments. It is estimated that each ounce of colorant added to tint paint may contain between 5 and 20 grams of VOCs. Darker color coatings, which require more pigment, could add 300 or more grams of VOCs per gallon of paint, above and beyond the VOCs contained in the solvent.

In general, higher concentrations of VOCs are found in extreme-durability solventborne polyurethane, acrylic topcoats, and pretreatment wash primers, where they run in the 5.0-6.5 pounds per gallon (600-700 g/L) range. Low-VOC water-based coatings typically contain less than 100 grams per liter, while 5 grams per liter is considered “very low” or “zero.”

California Leads the Way in VOC Regulations

While few regulations or standards exist for VOCs in outdoor environments, states such as California are taking a more aggressive approach.

The South Coast Air Quality Management District in California adopted (and has subsequently amended) Rule 1113 to tackle area source emissions of paints and coatings. It is the most comprehensive and strictest restriction in the United States. Many other states have adopted it, and many manufacturers have chosen to follow it as well.

The California Air Resources Board (CARB) also helps to regulate VOCs based on the unique environments and topographies of California and its 35 local air districts. CARB decides whether or not federal guidelines are appropriate for the region and where to tighten restrictions when necessary.

The EPA regulates VOCs outdoors mainly because of their ability to create photochemical smog under certain conditions. VOC-exempt status is granted only to chemical compounds that are negligibly reactive on forming ground-level ozone. To be classified as such, the coating must be listed on either of the lists of VOC-exempt materials maintained by the EPA or by SCAQMD under Rule 102. Note that just because a coating may contain VOC-exempt solvents and may be considered EPA-compliant in the United States, it might not be recognized as exempt by other countries.

While the Occupational Safety and Health Administration (OSHA) does not have a general air quality standard, it does require employers to furnish employees with a worksite that is free from recognized hazards (in the case of painting, by providing appropriate ventilation and respiratory protection) and sets limits on exposure to air contaminants and particulate release.

With less than 50 grams/L of VOCs, NeverFade original topcoat is one of the very few high-performance coatings to meet SCAQMD Rule 1113 environmental regulations. It also meets 40 CFR Part 59, Subpart D, the national volatile organic compound emission standards for architectural coatings, which is capped at 380 g/L. The topcoat’s complementary primers also contain less than 50 grams/L of VOCs.

PVDF Coatings Blend Safety and Performance

Some users of high-performance architectural coating technologies may believe that water-based coatings do not provide the same ease of use, long-lasting durability, extreme weatherability, and color-retention properties as solvent-based coatings. This is no longer the case thanks to the introduction of Kynar Aquatec^®, a polyvinylidene fluoride (PVDF) water-based resin emulsion. This tough, engineered thermoplastic has a 20-plus-year demonstrated record of performance in extreme conditions and serves as the binder in APV’s water-based restoration coatings.