When is it safe if ever to move back into a house where floors have been recoated with a solvent-based varnish or lacquer?


When is it safe if ever to move back into a house where floors have been recoated with a solvent-based varnish or lacquer?

Asked by Lali Parasuramar

My landlord has just redone our floors with a sealant that contains toluene (< 20%), methyl isobutyl ketone (< 15%), and xylene (< 10%). On looking up its MSDS, I've discovered that it is hazardous. I am asthmatic and have chemical sensitivities, and my son is 15 months old, so I am worried about when it will be safe to move back in. It has now been a week since the last of three coats was applied. Do you have any advice on how to help the toxic fumes dissipate? We have been trying to ventilate the house. We put raw onions in the house, and sodium bicarbonate also.

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Mary Cordaro's picture

Over the years, many of my clients have been in your situation and have asked me for advice on how to protect their home's indoor air quality. Unfortunately, there is no clear-cut answer on how long it will take for the odors and chemicals to completely clear, because it depends on several factors:

Your level of sensitivity. For some chemically sensitive individuals, even the smallest amount of odor may trigger reactions. Because sensitivities and possible reactions can vary greatly among sensitive individuals, please proceed with caution, especially since the floor products contain highly toxic chemicals that include toluene, methyl isobutyl ketone, and xylene. In addition, for many people, toxic chemicals can be highly ?sensitizing.? Therefore, if you expose yourself to sensitizing chemicals before the levels are low enough for your particular level of tolerance, you may become even more sensitized to them, and your tolerance level may drop even further. The result is that with each exposure, it may take lower and lower levels to trigger a reaction. In addition, you may become cross-sensitized to other chemicals. For more information on chemical sensitivity, The Chemical Injury Information Network (CIIN) is a support and advocacy organization dealing with Multiple Chemical Sensitivities.

Your child?s young age. Pound for pound, chemical exposure for children is much higher than for adults. Even extremely low levels of hazardous chemicals may be harmful to a very young child. There are several resources for more information on how chemicals affect children. The Environmental Working Group, or EWG, offers tools, tips, and further reading. The Children?s Environmental Health Network is a nonprofit organization that works to protect children from environmental hazards and to promote a healthy environment, with a useful resource guide to other organizations and links to other resources.

Fresh air exchange. If the house has been closed up, or even if the windows have been open, if adequate fresh air exchange has not been supplied from the onset of the floor finish completion, then outgassing will take longer.

Variations in chemical compounds. Outgassing time for chemicals will vary, depending on the chemical compounds, as well as temperature, humidity and fresh air exchange. Outgassing will take much longer if the temperature is low, if the humidity is high, and/or if there is inadequate fresh air exchange. For some chemically sensitive people, it can take several months, and sometimes years, for solvent-based products to clear. In some cases, when a home has been closed up, odor will persist even after many years. For health effects, you can look up the chemicals on various websites, including EPA.gov and Scorecard. One of my favorite organizations, the Collaborative for Health and Environment, offers a comprehensive database of chemicals and health effects.

Despite these variables, the good news is that there are still two simple things one can do to help mitigate this problem.

Use fans. The best method for decreasing outgassing time is the following: using large fans, or better yet, an industrial machine called a ?negative air machine" to pull in as much fresh air as possible, and exhaust the air out a window or door. The idea is to move as much air as possible, and to achieve as much air exchange as possible. In other words, out with the bad air, in with the good. Unless the humidity levels are high outdoors, this will greatly speed up outgassing and cure the offending products faster. You can rent negative air machines, also called air movers, from reputable mold remediation companies that are certified by the Indoor Air Quality Association.

Ask a friend. In your situation, after at least four weeks of good air exchange during which the outdoor temperature has been moderate and humidity levels low, and before you re-enter the home with newly finished floors, ask a friend or family neighbor who has an excellent sense of smell but who is not chemically sensitive to sniff the home first, with the doors and windows closed and fans off. If your friend or family member no longer detects odors, then stand in the doorway to the home and test the air with your nose. If you don?t smell anything, proceed into the home very slowly, tuning in to your sense of smell. If you start to smell even the slightest odor, do not proceed any further, and quickly exit to the outdoors.

For my sensitive clients, I recommend the outgassing procedure above for all curing materials, including for those products and materials that are generally considered safe for the chemically sensitive. This is because even nontoxic products and materials have an outgassing period, during which a highly chemically sensitive person may become sensitized. The outgassing time will vary from product to product, but even the longest-curing nontoxic products can take several weeks if the occupants are chemically sensitive. However, once safe products and materials are clear (outgassing is complete), there should be no reactions or sensitization.