How long does it take for VOCs to dissipate?

Contrary to what many may believe, it is quite difficult to predict how long it takes volatile organic compounds (VOCs) to off-gas from new materials in a specific building.  Sure, you can do chamber studies under controlled conditions to determine emission or concentration decays, but how the material will behave in the real world can be quite different.

On Friday I was hired to perform a follow-up assessment for a home under construction that is experiencing elevated VOCs from varnishes and paints applied almost 7 months ago.  One month ago I was in the home and found some very high levels based on measurements with a photoionization detector (PID).  While PIDs are not as accurate or detailed as other methods of measuring VOCs, they can be used as a good screening tool with immediate feedback.  I’ll write a blog post on the advantages and disadvantages of PIDs in the near future.

During my follow up visit a month later, I saw a 40% reduction after he followed some of my recommendations listed in this blog post: Reducing VOCs.  Unfortunately, this was still 4 times the outdoor levels.  We opened up some windows in a room and very quickly we saw a significant reduction.   Here are a list of the problems:

  • The home uses 2×6 “advanced framing” making the walls better insulated and tighter.  However, the home is not bringing in mechanical ventilation.  Many states have laws requiring mechanical ventilation.
  • The owner selected hardwood floor varnish and oil-based paints high in VOC content and emission. He should have used products listed in the GREENGUARD Environmental Institute Product Guide.
  • The owner moved in before the home was complete.  It would have been better to wait for the VOCs to dissipate more.

So back to the question at hand… how long does it take?  We can find some answers in a recent article in the Indoor Air Jounal titled “Decreasing concentrations of volatile organic compounds (VOC) emitted following home renovations”.  The authors found a return to “normal” VOC levels after 2-3 months.  The research was based on “real life” studies in Germany, not chamber tests.

Use the 2-3 month timeframe only as a guide, as my experience in the tight home with strong sources indicates it can take much longer.

184 thoughts on “How long does it take for VOCs to dissipate?

  1. Hi Ian,

    What a great resource! Tons of great information on your site. I wish I would have stumbled across this months ago. Just so there’s some context, here’s the situation: A single room was repainted with a Dunn Edwards water-based gripper product primer by a painter. All surfaces were painted — walls, ceiling, doors, trim and molding.
    Painter sprayed the product and entire house wreaked immediately for over a week. The smoke alarm kept going off as he was painting (weird, never had that). We had to leave the house for the weekend it was so bad.

    We’ve painted our home many times and never experienced odor like this. We left a fan exhausting air out, tried washing walls, heating room with space heaters… we even-primed over it with another product.

    Fast forward over four months later and the room still STINKS. If the doors and windows are open the smell is not noticeable. But, if we close doors and windows (normal sleeping situation) room WREAKS after an hour or two.

    I had an air test done and it showed higher than normal VOC levels (1400 ng/L), but not severe.

    To make things more interesting, I purchase a new piece of sheet rock from Home Depot and painted the primer (same cans, he left behind) and let it dry. NO ODOR at all. My conclusion is that the painter had something in his sprayer from a prior job or from cleaning it that made its way into the paint. The fact that ALL surfaces smell if you put your nose to them (walls, doors, trim, etc.) leads me to believe that’s common culprit. It could be some weird reaction with the prior paint on these walls, but from a common sense perspective that seems less likely to me.

    So, it seems that I have two options based on reading your post: (1) Wait … possibly a long time since it’s already been 4 months or (2) Rip sheetrock out and replace.

    My questions to you if you don’t mind are:
    1) How can I measure for VOC with spending a fortune? If it’s improving I may be willing to wait it out. I saw you mentioned a photoionization detector (PID). Is that something I could rent or acquire and understand the results to check progress?

    2) Any ideas at all on what could be in the paint that would have been used in an airless sprayer that might possibly be the culprit? I’m really just very curious at this point (so I can avoid issues in the future more than anything).

    Great site and thanks for keeping the thread going! Certainly sounds like I’m not alone!

    1. You could measure VOCs with a PID that you might rent. I don’t know of companies that rent equipment to the general public. Other VOC sensors that are not using a PID are not reliable, generally speaking. You could do tests at a lab, but those cost $100 a pop (or higher).

      Interesting theory about the sprayer. The mock drywall you painted… did you do that in the home or out in the garage? Maybe the way the product cured could explain some of the difference. I like a good mystery, so let me know if you figure anything out.

      Before ripping out all the drywall, you might want to consider an ERV to bring in continuous outdoor air ventilation. That will provide you with fresh air for many years to come, even after the paint issue has gone away.

  2. Thanks for the reply Ian. We found a national company that rents commercial grade PID devices. It will give a general reading unless it’s specifically calibrated to detect a particular VOC. Since none of the safety sheets reveal much with all the “low / no VOC” paints we used, we don’t have enough detail to program it for detection.

    That’s an interesting thought on the curing. The mock drywall was a fresh, unpainted sheet from home depot that we primed and painted in a different room.

    We’ve had a box fan exhausting 24×7 for a few months now and, as soon as the windows are closed… that nasty smell is back.

    We did trying repriming and painting and even then… weeks later, that same odor is present on all walls.

    I do plan on taking PID readings in all rooms and multiple in the offending room so I have evidence of the issue for reference.

    May have to chalk this one up to an expensive loss 🙁

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