What is causing high PM2.5 in my new house?
We’ve been living in our almost-completed house for a few months now. Passive style house, 0.22ACH50 with a fully ducted HRV. We moved in right after drywall was (mostly, I had to finish some and fix a ton of mistakes) complete, and started doing the painting ourselves. The drywaller left a mess all over the concrete floor, which I have been gradually cleaning up. After a while, I decided to set up my Dylos particle counter to see how we were doing with the air quality. Not too good. It’s hard to say what the average was, but depending on how much we moved around in the house, anywhere from 10-100 PM2.5 (estimated, the Dylos actually reads in particles per cubic foot).
Over the last several weeks, I’ve been running a couple of air cleaners when we’re not home (these are super loud), and gradually getting the house cleaner. I haven’t seen an overall reduction of the particulate matter. When I come home and the air cleaners are running, the reading on the meter is near zero (<0.5). However, all it takes is to walk around the house for a little while before the numbers are up over 10 again. Similarly, at night when no one is moving about, we see readings of <3. So this tells me that whatever it is, it’s stuff that is heavy enough to be settling out on the surfaces, and stirred into the air with movement (but not significantly stirred by the flow of ventilation air from the HRV).
What I find most puzzling is the readings after turning off the air cleaners. They were running for hours with readings near zero, and these things push about 800CFM, so I would have thought they would stir up at least as much particulate matter as us walking around the house. And yet, we start walking around the house and the numbers go through the roof.
So my questions:
where is this PM likely coming from? The unfinished edges of drywall (we haven’t trimmed doors and windows yet)?
what else can I do to lower the numbers?
We do have a recirculating range hood, but the pattern of high PM happens even if we haven’t cooked for days. I see a separate rise and fall of PM when the cook top or oven is used. I really don’t think what I’m seeing can be explained as days old smoke getting stirred up, but maybe I don’t understand the nature of smoke as well as I think.
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