A recently completed coatings-industry study is reported to cast doubt on the wisdom of conventional regulatory policy on volatile organic compounds (VOCs) in architectural and industrial maintenance coatings.
|ACA says the study raises questions about the wisdom of regulatory policies on coatings VOCs as contributors to low-level atmospheric ozone pollution. Above: Los Angeles on a smoggy day.|
The study, conducted by the American Coatings Association (ACA), raises questions about the effectiveness of existing regulatory programs and rules, which the industry says treat all VOCs as “equal” in their impact on air quality.
“VOC content has become the primary indicator of environmental acceptability for coatings,” ACA says in the Executive Overview of its Paints and Architectural Coatings Environmental Study (PACES). “This approach, however, has limitations.”
The research was funded by the coatings industry, and was assisted by a “technical advisory committee” comprised of coating manufacturers, raw material suppliers, and representatives of ACA, the Environmental Protection Agency, the California Air Resources Board, and the South Coast Air Quality Management District (SCAQMD).
SCAQMD has long imposed the toughest air-quality regulations on architectural and industrial maintenance coatings nationwide, as part of a battery of state, local and federal regulatory policies aimed at addressing the Los Angeles area’s much-documented air-quality issues.
In the executive overview of the PACES research, ACA says existing regulations on VOCs “give little regard to ‘reactivity,’ which is the variable ability of VOCs to promote accumulation of ground-level ozone. Different VOCs have different degrees of reactivity; some VOCs may be orders of magnitude more reactive than others.”
In addition, ACA says these current regulations fail to take into account the limited atmospheric “availability” of some VOCs to contribute to chemical reactions that produce ozone pollution.
Finally, ACA says in its report on the study, existing regulations fail to take into account the “life cycle” of coatings, based on performance factors such as coverage, durability and service life. In other words, VOC emissions may actually be reduced if higher-performing, longer-lasting coatings are used, even if these coatings contain and emit higher levels of VOCs.
ACA says it launched the PACES research in 2006, to “gather scientific data needed to evaluate total environmental impacts of the regulatory trend toward increasingly stringent” VOC limits on coatings.
Two Phases of Research
In the PACES research, ACA set out to develop models to measure ambient air concentrations of TPM (Trimethyl Pentanediol Monoisobutyrate), commonly known by the trade name of Texanol. The solvent is widely used as a coalescent, or film-forming agent, in water-borne coatings.
“Historical ‘micro level’ studies suggest that as much as 40% of TPM never evaporates from paint films, and is therefore not available for participation in ozone photochemistry,” the report on the study says.
ACA says it developed analytical instrumentation and measurement protocols for TPM but could not measure “elevated TPM concentrations downwind of painting operations” due to movement of the downwind “plume.”
The study also analyzed VOC content and emissions from the use of thinners, additives and cleanup solvents, but excluded disposal of waste paint and solvent from those calculations.
Nevertheless, the study conceded, “preliminary analysis” indicates that regulating architectural coating VOC content “appears to have decreased VOC emissions from such coatings over the last several decades,” even while use of those coatings “has increased significantly.”
In Phase 2, researchers continued ambient measurements of TPM in the Los Angeles air basin, and attempted to measure the availability of TPM for purposes of ozone production.
Among those findings were the following.
• About half of TPM “was ‘lost’ from the paint film” within 90 days of painting. Almost 90% of TPM was lost within six months. At 11 months, about 12% of the TPM remained.
• Analysis of gypsum wallboard samples painted nine to 17 years earlier in California and Texas found that all “contained residual TPM” in concentrations ranging from 300 mg/m² to more than 2,000 mg/m².
The analysis “indicates that decades would be required to completely deplete the residual TPM, less any portion retained permanently,” the study found.
• An analysis of ethylene glycol and propylene glycol in latex paint found that emissions varied with the type of paint and substrate.
For example, the study reported, flat paint was found to produce higher emissions than semi-gloss, and stucco substrates more than gypsum wallboard.
ACA’s overview report on the study says preliminary analysis of available data shows that regulation of VOCs in architectural coatings “appears to have decreased VOC emissions from such coatings over the last several decades,” even while coatings use increase significantly” as a possible result of population growth, development, and higher per-capita consumption.
Additional Study Suggested
The report says comprehensive assessment of total environmental impacts of architectural coatings requires additional data and study
“Coverage and durability of coatings, and the reactivity and availability of their VOC contents, are important issues that need to be better quantified,” the report says. “Questions as to whether there is a need for reformulation of paint in the context of durability, cost, and environmental benefits remain unanswered.”
Future research should focus on the acquisition of data needed to complete a comprehensive life-cycle assessment, the report says.
Report Stops Short of Direct Challenge of Current Regulatory Policy
While it highlights questions related to existing regulatory policy on VOCs in architectural coatings, the ACA’s report on the study stops short of directly challenging the validity of “mass-based” VOC regulatory programs—policies that essentially treat all VOCs the same, regardless of atmospheric reactivity, life cycle, or “availability” for chemical reactions that produce low-level ozone pollution.
ACA said the report “may provide a defensible technical basis for future regulatory policies that account for the variable atmospheric of latex-paint cosolvents.”