[Strawbale] Forced air systems and particle resuspension

[Speireag Alden]

On 2008, Jan 07, at 09:40, dfugler at cmhc-schl.gc.ca wrote:

> Here is a graph from one of our research projects where we measured
> particles in houses.

     Thank you!  That's very interesting.

> What I would like you to look at are the peaks in the "sous-sol" or
> basement air during the first night, so around 3 a.m. to 7 a.m.  
> There are
> these almost imperceptible 1 µg/m³ peaks that are likely due to the
> furnace turning on once an hour. So, you are correct in that it is
> discernable with specialized equipment. However, since houses  
> typically
> range from 5 to 25 µg/m³ in PM10 and since the big peaks are the  
> source of
> your major exposure, these tiny disturbances caused by activation of
> forced air systems are not big contributors to house airborne  
> particles.
> Really big peaks are caused by people getting up in the morning,  
> walking
> across the carpet, cooking breakfast, doing some cleaning,

     I'll bet that vacuuming puts it off the scale, unless it's a  
central system which exhausts to the exterior.

> One of the houses in this study showed high particle counts
> whenever the kid rolled over in bed. His duvet was rarely cleaned  
> and it
> gave off huge numbers of particles everytime he moved.

     Wow.  That suggests to me that generalization is very difficult  
in this situation.  However, it also suggests that the problem is  
very amenable to point-source solutions.

     It would also suggest to me that special cases might be very  
significant.  For instance, suppose there is a seldom-cleaned carpet  
directly in front of a hot air register?  Every time someone walks  
across the carpet, there could be a very significant plume of  
particles, actually generated from the carpet, but distributed by the  
moving air.

     What do you think?

> Contact me directly if you have any further questions. This is  
> probably
> getting too esoteric for a general straw bale conversation.

     I don't think so.  This sort of discussion is excellent food for  
thought, and very useful in archives.

-Speireag.