The removal of VOCs from flooring adhesives has become one of the most significant changes to construction materials that has taken effect in recent memory. I think it’s worth a look at the reasoning behind the change, along with the downstream benefits and detriments that resulted.
The change came about originally as a result of the United States signing on to the Montreal Protocol on Substances that Deplete the Ozone Layer on September 16, 1987, and also accepting its subsequent amendments. For background, refer to EPA’s Basic Information page on ground level ozone, which states, in part:
Tropospheric, or ground level ozone, is not emitted directly into the air, but is created by chemical reactions between oxides of nitrogen (NOx) and volatile organic compounds (VOC).
Ground level ozone- what we breathe- can harm our health. Even relatively low levels of ozone can cause health effects. People with lung disease, children, older adults, and people who are active outdoors may be particularly sensitive to ozone.
The EPA later made the limits more stringent than were allowed by the original Montreal Protocol limits; in 2010 they revised the primary ozone standard down from 0.075 parts per million (set in 2008) to 0.06 parts per million, based on epidemiological studies showing adverse effects in otherwise healthy adults. A review of studies is available from the EPA, released in 2009, here. In very brief summary, a collection of studies found correlation between an increase in respiratory symptoms and exposure to ozone concentrations of .06 ppm. The test measured the volume of exhaled air in test subjects, making it a quantitative measure, not just surveying subjects about symptoms.
Based on the findings, the EPA appears to have firm scientific data allowing it to promote the reduction in ozone concentration, and since ground-level ozone is a by-product of VOCs, to limit those VOCs as well.
Before undertaking to research this topic, I was not aware of the connection between VOCs and ozone, I also doubt most design professionals or specifiers understand this was the rationale behind the change. I personally assumed it was an indoor environmental quality concern – reducing noxious fumes for occupants, etc. It’s likely a happy side effect of eliminating the VOCs – concentrations of ozone in buildings has most likely been reduced.
That brings us to the part that every architect, specifier and building owner knows only too well. When the VOCs were eliminated from the adhesives, the replacement products were very good at adhering to the new regulations. They were not, unfortunately, useful at all at adhering flooring to substrates. Replacement adhesives were water-based, meaning that emitted moisture from substrates would dissolve the adhesive, and floors failed in massive number. Additionally, the dissolved glue in the water-based adhesive was beloved by mold spores everywhere, and any health benefit gained by reducing ozone was overtaken by the hazards of high mold concentrations in the indoor environment.
Flooring manufacturers recognized the problem early on, and started placing stricter limits on the volume of moisture allowed to emit from subfloors. A limit of 3 pounds per 1000 square feet per 24 hours (tested by the rightly-much-maligned ASTM F1869 calcium chloride method) or 75% RH (tested by ASTM F2170 probe method) was not unusual to be called for and extremely unusual – almost unheard of – to be obtained. Various methods were attempted to control the moisture flow, including vapor barriers under the slabs, sheet membranes under the flooring, sprayed-on films, epoxy coatings, and additives to the concrete. There are benefits and pitfalls for each of these, but that’s a topic for technical articles (and myriad lunch ‘n’ learns) and not a skeptical treatment, but it is useful background. In the end, we seem to have settled on solutions (either additives in the concrete or epoxy-based toppings) and the not insignificant costs of these solutions are now built into every job. The water-based adhesives are also improving, and some are able to adhere to substrates with over 90% RH, alleviating some of the need for expensive treatments.
Decisions like the one the EPA made are addressing big picture human health issues. Whether or not they gave thought to downstream impacts is immaterial; manufacturers were bound to follow the new VOC limitation rules. It took a significant amount of time for the industry to change the way it specified and implemented flooring preparation and installation. One worthwhile takeaway would be for various segments of the construction industry to communicate more effectively about the impact of externally-mandated changes to known products and systems. If specifiers are made familiar with what decisions are being made and the reasons for those decisions, they can offer sound technical advice to clients and designers, and be in a position to impact the industry.
The Skeptical Specifier 