Outgassing has emerged as one of the important buzz words in indoor air quality circles. It most often refers to gases that are emitted by synthetic materials as they age or degrade. For example, new particleboard outgasses formaldehyde from its glue. New floor finishes release VOCs as the coatings dry. Freshly installed carpet releases that "new carpet smell".
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In the past, no one even considered the fact that there might be any negative health effects related to outgassing. When we sat in a new automobile, we deeply inhaled the new car smell believing it to be a symbol of something pleasurable and satisfying. You could even buy aerosol cans to replenish the odor as it dissipated over the first several months of the car’s life. More recently, we have come to understand that many of the synthetic chemicals given off by new materials are harmful to us.
Many manufacturers are reformulating their products so consumers and installers are exposed to fewer VOCs than in the past. These low-VOC products are on shelves in your local building supply or home improvement center. Some states are regulating the VOC content of paints and adhesives. These regulations will definitely improve indoor air quality, but surprisingly, the regulations weren’t originally developed for that purpose. They were designed to combat smog. Areas like California, New Jersey, and New York City that now require low-VOC paints have notoriously high levels of outdoor pollution. VOCs tend to be a significant component of smog, and the laws were passed to improve the quality of the outdoor air.
The Time Factor
While it is best to choose products that don’t outgas VOCs, 100% inert materials aren’t always available. Fortunately, there are ways you can use some of these products relatively safely. This is because outgassing decreases with time. A newly manufactured product that is subject to outgassing will only contain a limited quantity of VOCs that will eventually all be released. Most of them will be emitted fairly quickly. If the material can be stored somewhere, such as in a garage, until the outgassing period has ended, then it can be brought indoors and installed.
If the odor of fresh paint is intolerable, you could take a vacation for a week or two until the majority of the outgassing has dissipated. Some paints tend to lose their odor relatively quickly, in a matter of a few days. However, your sense of smell may not be acute enough to tell you when the outgassing period has truly ended. Unfortunately, time will not solve all of your outgassing problems. For example, medium-density fiberboard (often used in kitchen cabinets and for closet shelves) typically contains a very large percentage of formaldehyde-based glue. This reservoir of glue is so potent that formaldehyde will be released in significant amounts for years to come. Such products’ “half-life” can span up to six years. In this case, half life refers to the amount of time it will take for half of the formaldehyde to be released. For example, it can take six years to lose half of the initial amount of formaldehyde, six more years to lose half of the remainder, and during every six years thereafter, only half of the remaining formaldehyde will dissipate.
The half-life of formaldehyde and other VOCs is affected by a number of factors, but humidity and temperature are the most significant. Higher temperatures and higher humidities mean a shorter half-life. For example, a new mobile home (which contains a great deal of formaldehyde) located in Florida will outgas formaldehyde at a faster rate than one in a cold, dry climate. If a mobile home is located in a northern climate, the overall indoor formaldehyde levels may be lower, but they will last for more years.
One of the problems with VOCs is the fact that they haven’t been studied sufficiently to determine how long they take to outgas completely. Nor have enough data been accumulated to know consistently which VOCs are the worst offenders. Therefore, while you can reduce your risk by allowing a product to outgas awhile before exposing yourself to it, no one can say for certain just when a product can be considered totally safe and inert.
The “Bake-Out”
Some scientists are suggesting that you “bake out” a new building to reduce the levels of VOCs. This suggestion is based on the fact that VOCs outgas quicker at higher temperatures. If you simultaneously raise the temperature inside a new house to 90 degrees and provide extra ventilation, it is believed the VOCs can be removed rather quickly. The high temperature causes rapid outgassing and the increased ventilation gets the gases out of the building before they can be reabsorbed. According to the scientists who are working in this area, the process is supposed to take at least three days to be effective.
Not all researchers are in agreement that a bake-out will actually work. They point out that it won’t be particularly effective with manufactured wood products such as particleboard since those materials contain such a large reservoir of formaldehyde that it takes years to lower the formaldehyde levels significantly.
Many times, heating up an entire building and “baking” for three days does a good job in releasing some VOCs, but not others. For example, most furnaces and baseboard heaters are painted, and while the paint may have no discernible odor when they are cool, the first few times they are heated up, the high temperature can cause the finish to outgas. Some baseboard heaters have a fairly strong paint odor even after two or three months of use, but others are relatively inert after an hour or so.
When you go into a new building that has had the temperature raised to 90 degrees, you will usually be able to detect a strong odor as some of the VOCs are released from the components of the building. Something is obviously happening. In some cases, a bake-out is a simplistic solution to a very complex problem, a technique that may or may not live up to its expectations.
If you are considering a bake-out, it is important to know that high indoor temperatures can harm some furnishings. Your musical instruments, phonograph records, candles, etc. could easily be damaged. The bake-out process may also cause some chemicals to be released that would remain inert at normal temperatures.
Baking out products during the manufacturing process seems to hold more promise. Factory-applied baked-on finishes on metal siding, roofing, and cabinets are usually much more inert than other finishes. This is because manufacturing plants can design a specific bake-out technique for specific VOCs and apply it to their specific product before it is shipped out to consumers. Already, some companies are reformulating their products and manufacturing processes so that they release lower levels of formaldehyde and other VOCs, but it is an area in which more work needs to be done.
Even if you can use the time factor or a bake-out to reduce indoor levels of VOCs, you must keep in mind that the chemicals are being released into the outdoor air. This in turn contributes to outdoor air pollution.
(This article is from the archives of the original Healthy House Institute, and the information was believed accurate at the time of writing.)
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