• READER QUESTION:  What’s that smell?  Polyurethane

READER QUESTION: What’s that smell? Polyurethane

My husband refinished the floors in our house. My 2 year old and I went on vacation during this time. He used a couple coats of polyurethane that he finished applying on a Saturday. We came home over a week later, on a Sunday and the house still smells. We’ve been staying in the house now for 2 weeks and I found out I am pregnant (about 5 weeks along). I can’t tell if the floors still smell or if I’m being paranoid about it but my question is this- if we were away for about a week while the polyurethane dried could we still be affected by it? Mostly concerned about my pregnancy. Thank you



Thank you for your question.  Many people enjoy doing DIY projects around the house and refinishing floors is one of them.  Your concern centers around the odor you have notice even a week or more after the floor finish was applied and the potential effects on your pregnancy.

Floor refinishing generally involves sanding to remove the old finish followed by application of varnish as a protectant/sealer and appearance enhancer for the wood.  Dusts from the old finish and wood removed during the sanding process could cause irritation to the lungs, sinuses and throat of the person who did the work.  These issues can be minimized by using an appropriate and  properly fitting dust mask.

To reduce the likelihood of dust transfer to other parts of the home during the sanding process, heating system ductwork as well as doorways to other parts of the home should be sealed with plastic film.   After sanding, the dust generated needs to be thoroughly cleaned up both to achieve the best appearance and to reduce spread

Polyurethane varnishes are mixtures of several components.  Generally the polyurethane and other solids in the varnish are suspended or dissolved hydrocarbon based liquid like Stoddard Solvent.   Some newer varnishes use a water based mixture to minimize exposure to volatile hydrocarbons (VOCs) and to allow clean up with soap and water.   Solid components may include silica, which is added to reduce the gloss of the varnish once it has dried.  The presence of silica in the product may prompt labeling that the product contains substances known by the state of California to cause cancer.   If your product contains this warning and it is a low gloss or satin product it likely contains silica. Silica may cause cancer in persons inhaling silica containing dust, but is not likely to cause any problems during application of the varnish or to people living in the home after the product is applied.

The odor you have been detecting is the result of volatile organic compounds or VOCs being released into the air after the floor finish was applied and during the drying process.  Health effects from short periods of exposure to VOCs may include eye and respiratory tract irritation, headaches, dizziness, visual disorders, fatigue, loss of coordination, allergic skin reactions, nausea, and memory impairment, while long periods of exposure can affect the liver, kidneys, and central nervous system1. Floor finishes like paints usually contain some level of VOCs.  Polyurethane floor finishes can be oil-based, solvent-based or water-based.  The water-based floor finishes may still contain small amounts of VOCs as coalescing2 agents. The U.S. Green Building Council reports that off-gassing of oil-based finishes can last for months or even years, while water-based products are largely finished off-gassing within a few days.  In addition, conditions during and after the floor finish application like air flow may also affect how long you experience an odor.  You always want to have good ventilation when applying any kind of paint or floor finish products indoors.

Uncured or undried polyurethane can potentially be irritating to the lungs, sinuses and other parts of the respiratory system.  As the varnish dries and the polyurethane cures it becomes essentially inert and nontoxic.  Curing time is variable, but most modern varnish products should cure very quickly. Water-based polyurethane varnishes dry more quickly and typically have less of a solvent smell. Some hydrocarbon based varnishes have a strong odor that may persist for several days after application.  The person at highest risk for exposure to the solvent is the person applying the product.  Inhaling VOCs can lead to irritation of the respiratory tract (lungs, airways sinuses and throat) as well as eye irritation, headache, dizziness and more.   A proper vapor mask to minimize inhaling VOCs during the application should prevent most of these problems.

VOCs should quickly dissipate as the varnish dries and the solvent evaporate.  Most houses have a complete turnover of air several times an hour and the process can be sped up opening windows to thoroughly ventilate the house during the drying process. Once the product has dried and the house has been aired out any risk of solvent exposure is minimal. The smell associated with the new finish may linger for much longer than the toxic fumes.

Since you were gone during the application process and for roughly a week after the product was applied, any risk to you, your 2yo, or the baby you are carrying is likely to be minimal. Check the label for any health warnings or listing of ingredients.  The Consumer Products Safety Commission (CPSC) requires warnings on the label for chemicals that are possible, probable, or known to have human developmental and reproductive toxicity3.  The label should also contain a phone number for additional information if you have any additional questions or concerns.  Please see the U.S. Environmental Protection Agency’s Tips for Preventing Exposure to Paint Fumes in the document Promoting Good Prenatal Health: Air Pollution and Pregnancy4.  You can also speak with your health care provider regarding your concerns.


Author:  NSF International and Cincinnati Drug & Poison Information Center


  1. See National institute of Health VOCs and USEPA Volatile Organic Compounds’ Impact on Indoor Air Quality
  2. The merging of two or more droplets, bubbles or particles into one.
  3. Consumer Product Safety Commission 16 CFR Part 1500
  4. Promoting Good Prenatal Health: Air Pollution and Pregnancy. Information for Prenatal Health Care Providers. USEPA Office of Children’s Health Protection and Environmental Education Child and Aging Health Protection Division (1107A), EPA-100-F-09-020, www.epa.gov, January 2010

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