Hi, We've done a lot to try to preserve indoor air quality on our project (solid wood, not chipboard, low-voc paints, etc.). Since we had been told that the air in a house just after construction is like "sandpaper for your lungs", it had been our goal to leave the house empty for a month with HEPA air filters running to get all the fine particles out of the air. But is a month too much? (I had actually heard that it takes 'months' for all the dust to settle because it's so fine, but I don't know for sure.) We budgeted an extra month on top of this but problems with our finishes have held us up for weeks now and it looks like we might only have 2 or 3 weeks to clean the air. How long would it take? We can open windows, use compressed air to blast the ceilings and walls and keep the dust moving/falling, fans to blow it all outside, etc. But is this effective? Am I herding cats? We're just not sure how difficult a task it is to remove micro-particles from the air. Any thoughts? Thanks! -Colin.

I think you are making a 'mountain out of a mole hill', so to speak. Unless someone in your family has severe respiratory problems, I don't think you have a problem with the air quality. Assuming your have cleaned the project regularly during the construction process, the only real problems left by movein should be residual drywall dust and leftover particles of your finishes. A couple days with a HEPA filter should remove 99+% of this. Odds are good that, if you live in any type of suburban area, the inside air will be cleaner than the outside air.

did your HVAC system run during the course of construction? you may want to make sure the coils are cleaned and free of drywall/wood dust

My wife has asthma (not severe but it's a problem) and we had talked to two different building science guys who thought post-construction air was a hazard.

I don't have any experience with HEPA filters; will we be able to see the residue on the filter? e.g,. 'bad' air will show a build-up on a clean HEPA filter within x days.


We just have the HRV (radiant floor for heating) and it hasn't been turned on yet. Ducts are blocked so they should be clean when it gets turned on.

I'd be very interested to know if others agree with Wes about how long it should take to clear the air. (It would be a relief, if so -- but more important that I know the bad news if there is bad news!)

Thanks!
-Colin.

First off, I'm a long way from being a rabid indoor air quality advocate, but I don't condone needless dusty, dirty air either. My wife is a bit sensitive to dust and so far in our new house she has had no problems at all. That's even given the fact that construction debris is still laying on the crawl space slab, (cleaning it hasn't climbed the priority list yet) which is the HVAC supply plenum, and there's dust in the attic, which is the return air plenum. I see more dust, dirt, and dust bunnies, around the house from the dirt our feet and the dogs track in, and from the hair the dogs shed. The HVAC filter is getting dirty, but not very fast at all, no where near as fast as the rental house we were living in. I don't know what you have for floor covering, but hardwood and tile floors will give you cleaner indoor air than will carpets.

You're right to be concerned, but I agree you may be making a mountain out of a molehill. If your wife is extremely sensitive you may want to consider an electrostatic filter along with the HEPA filter.

The air should not be a problem after construction. The main problem is left over dust around the house that may be picked up later, and any dirt/debris that get into the AC system. If the system is turned on at all during the construction, you should install a high rated filter on all of the return vents. This will help keep most of the dust out of the system. Additionally, before moving into the house, you should get somebody to do a thorough cleaning of the house. Drywall dust itself is very fine and can get in small cracks and corners. Additionally, you should get somebody to clean out the duct work. While the vents may be covered now, theres no guarentee that it was covered the ENTIRE time during construction. Additionally, for houses I have seen under construction, they just put sheet metal over the openings. While this may stop most debris, the smaller stuff can still get in. Additionally, after the house is cleaned and the ducts cleaned out, you should replace the filters again. There will always be some dust in the system/air, but this will help remove 99% of the dust caused by the construction.

Dust can be filtered and vacuumed out in a short time if you keep it stirred it up.

I'd be more concerned about VOCs. You might consider small amounts of ozone for that - it certainly works to knock out paint odors.

Thanks; this is all reassuring.

We've done what we can to reduce VOCs in the products we've installed (e.g., opting for solid wood instead of chipboard anything, fiberglass windows, etc.). We'll be sourcing a low/no voc paint for the walls when we get to that stage.

Thanks!
-Colin.

Here is a reference to using ozone to bring new house VOC levels down by 66% to 95%. Probably less expensive and more effective than waiting.

http://hkms.org/Documents/Lowen%20n%20Associates%20Rpt%20030822.pdf

Mind if I ask which fiberglass windows you used?