Reply by clin

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Posted on Your dust collection knowledge can help more than in your shop!

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929 posts in 1139 days

#1 posted 02-22-2016 06:05 AM

Clin.. please post your findings on LJ s, at least in this post (since it s not EXACTLY wood working related but yet it is ) :)
I am curious to see any relationship between the shop & house for fine dust.

- Holbs

To be clear, I DO NOT think the dust in my house is from the shop. Sure, some might be. But my point was not that I think I’m contaminating my house. Rather, that there seems to be something going on that can really cause some high readings.

Note: As near as I can tell, even these high readings are not extremely bad, but do get into the “moderate” and “unhealthy for sensitive groups” ranges. I base this off of this online calculator that converts particle level in ug/m^3 for less than 2.5 um (PM2.5) to an Air Quaility Index (AQI) value.

Since particles have been historically measured by density (mass per volume of air) and not actual count, I have to convert the particle count of the Dylos meter which is in number of particles per 0.01 cu. ft, to ug/m^3.

This is complex and requires a lot of data we just don’t have, like particle density and porosity. But apparently, it has been shown that you can take the Dylos reading and simply divide by 100 and get a good approximation the dust density in ug/m^3.

WARNING: The following are my understanding of how to convert Dylos readings to air quality index values. I could have this all wrong.

So for example, in my shop and walking around (kicking up some dust), the Dylos usually reads about 150 for the fine particles. So this is approximately 1.5 ug/m3 and an AQI of 6, which is in the good range. I think I’ve only seen it exceed 1,000 a few times. So this is ~10 ug/m^3 and AQI = 42 (still just inside the good range of 50).

I do run my Jet room filter any time I’m making dust (and well after) and vacuum up after each work session. I think this helps.

In my bedroom, during the night, the room filter keep things in the 100 range on the meter (1 ug/m^3) or an AQI of 4. But I’ve seen a few times, large hours-long peaks in the range of 7,000 (70 ug/m3) AQI = 158 which is unhealthy. Though as mentioned most of the time at peaks are less than 2,000.

Note: Take ALL these calculations and approximations with a grain of salt. These have come from my searches on the internet trying to relate Dylos readings to air quality. I could easily have misunderstood something and have these conversions wrong by orders of magnitude.

These peaks have been without the bedroom filter running and taken around 4 pm to 10 pm. We’re not in the bedroom then. Though just today I decided to run the filter 24/7.

I don’t know what is causing these peaks. Best guess is that cooking dinner is getting particles in the air. Though I’ve not correlated this yet. And these peaks have happened on days where the central air system has NOT come on. So there would be very little air movement from the kitchen to the bedroom. It’s a large house and the bedroom is some distance from the kitchen. Though it’s not a mansion either.

But, I think these peaks could be dependent on wind speed and direction perhaps affecting air pressures in the house. For example, pressurizing the attic space and forcing very dirty air into the house through ceiling light fixtures and other cracks. Or perhaps there is some part of the house with a lot of dust, and a given wind speed and direction, and combination of doors opening and closing that accounts for this. I just don’t know.

This all has me interested in doing something to ensure better air quality in the house. Perhaps whole house filtering, or some DIY filters like Bill Pentz uses in in house.

-- Clin

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