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VOCs

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.

By Ian Cull

I'm I.A.N. the Indoor Air Nerd. I'm a speaker and consultant on indoor air quality issues. To learn more about me, click "about" at the top of this page.

196 replies on “How long does it take for VOCs to dissipate?”

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!

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.

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 🙁

We just installed new engineered hardwood by Johnson Hardwood on our concrete slab. They claim to be Carb II compliant. The floors are only in a week, but I am getting a massive headache whenever I am in the house since the day they went in. It’s about 1100 square feet that covers the whole downstairs. It was a tongue and groove floating installation. Nothing else seems to be causing this. How many weeks are reasonable to expect this to stop. I have heard this can take years in some articles I have read. If that’s true, I couldn’t possibly keep them. We’ve had the windows open for days with the central air fan running to circulate fresh air. But as the winter approaches I can’t keep the windows open. I am growing concerned.

Just ripped out 1500 sq ft of tounge and groove wood flooring, it was so Noxious during the year out I had to wear a respirator…. it ended up With very high levels of formaldehyde

Hi, thank you very much for this helpful article and the info on your site. I was diagnosed with an autoimmune condition a few years ago and have become much more aware of how the products we use can affect our health. However, I seem to have made a mistake in the last week, as we are furnishing our toddler’s bedroom. I purchased a freshly-painted wood dresser from someone who gives old furniture a new life. When we brought it home, I realized the paint was so new that I scuffed it so I asked for the info on the paint so I could touch up as needed. That’s when I saw that the paint may contain high levels of VOC’s. The primer, purchased at Home Depot, said it contained no VOC’s, but that the added colorants could significantly increase the VOC content. Our dresser is black. And I confirmed with our local Home Depot that the colorants used were not low-VOC. We moved the dresser out of our daughter’s room and into a guest room with the window wide open last night. Given our health concerns, what are your thoughts on best next steps? Keep the dresser in the ventilated guest room and find something else for our daughter’s room? Store the dresser in a garage for 6 months? Really appreciate any insight you may have!

@Shal,
This is where instruments come in handy. It’s highly likely that a few days in a well-ventilated room is enough to eliminate the majority of VOCs. But a measuring device would be able to confirm that. In the absence of being able to measure VOCs, I would keep it in a well-ventilated room for a week and then determine if I could still smell anything.

Thanks so much for your kind reply, Ian. We were able to move it outdoors to the deck, which hopefully helps with dissipation as we’ve had some 80-degree days.

I’m trying to decide between water based and solvant based concrete sealer for a slab that will be used as the floor inside a residence with a tight envelope and ERV. The solvent based seem to be a better product and the water based are low VOC inherently. After the application process, once the floor has dried, do solvent based still have higher VOCs? If so, how long does it take for the solvent based sealant to get to a point where it is not releasing VOCs? Perhaps the 2-3 months is the answer?

@David,

With a tight building enclosure, I would recommend the water-based sealer. There are too many variables to give an exact timeframe, but the time it takes for solvent-based products to sufficiently off-gas is probably measured in months. You’ll need to determine if the improved performance of the solvent-based product is worth the indoor air quality risks.

We had our living room ceiling painted with zero VOC paint only to learn belatedly that zero VOC isn’t good enough. That was three months ago and the room is still unlivable. We’ve had windows and doors open and fans running all day every day since. We suspect the painter didn’t give the paint enough time to dry before recoating (3 coats in 6 hours). Two months after the first paint job we tried Safecoat primer, which only made it worse. We waited another 3 weeks and put on a low emissions finish coat and are just waiting. Hoping. Windows open. Fans running. It’s quite frustrating. It smells okay when the windows are open but overnight the stench becomes oppressive. I’ve been trying to better understand how off gassing works and where all those VOCs go. In particular, is it possible they settle again on other surfaces in the room and continue to stink? I’ve see off gassing cars leave a film on the windshield and noticed that when I had a bucket of water in the newly painted room it developed an oily sheen on top. Could that be from the off gassing? Could that same residue be settling on the walls and floors of the room? Are there good resources/reading for me to gain a more in depth understanding of this process? It’s hard to believe this is taking so long.

@Hanna,

Sorry to hear about your ordeal. One way to think of VOCs in paint is that it’s like water. If you apply water to a surface, it will eventually evaporate, but the humidity that’s now in the air could condense on a surface (cold window), then heat up and evaporate again. The same thing with VOCs in paint. They could evaporate then condense back down on a cold surface, then re-evaporate when the surface warms up. When the VOC molecules go out the window, they are finally gone. Until then, they are still in the home. Heating the room up can get more VOCs into the air, but then you need to get that indoor air to leave the home to truly get them out.

It sounds like something that wasn’t really no-VOC was applied along the way.

Great blog!! Without well-established metrics for health impact and best standards, how can consumers understand liability (if any) for developers that use old, irresponsible, and environmentally unfriendly materials such as old paint, toxic adhesives, etc? Damages seem like they would be mainly long term and difficult to quantify. Plus rectifying the irresponsible behavior seems difficult with your advise basically being “open windows” and buy gas phase purifiers. I totally agree, but if it’s cold, or there’s pollution, the homeowner is basically stuck with the issue with little help.

Suspect formaldehyde is making me ill since last 4 months. Took all items not solid wood out of home. Wanting to test for formaldehyde in the home. Used the cheap hour long test from big box store but not sure of accuracy. Doc wants better test of home air. How is this done? Where do we get test equipment? Also, live next to funeral home that does 1st floor embalming w / outside venting. Is an exposure w/i 100 feet possible? Could it travel or effect my home ? Strange, but true.

If you provide some information about the test you did from a big box store, including the laboratory that provided the analysis, I might have some feedback. The most reliable ways probably involve hiring someone to collect the test.

My hunch is that there would only be a very minimal amount outside your home (100 feet away). And even then, it would be highly variable depending on the wind.

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