A preliminary air quality analysis of my shop

[phil (admin)]

Background: My shop is in my basement. I have a Ryobi BT3K, a small Inca (8-5/8" wide but short bed) jointer/planer, Inca 9-1/2" bandsaw, A Ridgid oscillating belt sander, and a router table with downdraft box. I use a Ridgid shop vac with 2-1/2" flex hose network for "dust" collection (along with a separator).

All my tools have 2-1/2" or smaller ports. I have a couple of different dust collectors but I don't use them because I just can't run 4" piping (perhaps some day I will figure out a way to do this--my shop is TINY). My shop vac gets about 150-160 CFM w/o separator. With the separator and network I get about 125-CFM. Absolutely not enough for collection of fine dust.

So the more I read Bill Pentz's site (among others) the more concerned I've gotten that I'm breathing boxcar loads of super-fine dust. That, this dust never settles and every time I enter the shop I breath more of it.

I realize my setup is sub-optimum, but the question is, how much of a price am I paying for it?

Recently I stumbled upon a particle counter that is really geared towards homeowners. It uses a laser to count particles in two sizes.

From the manual:

"Small particles are all particles detected by the DC1100 right down to its detection limit--typically below 1-micron. Large particles are all particles detected above the large particle threshold which is typically around 5 microns."

The meter comes with a table to help interpret the readings:

0 - 25 Excellent Air Quality
25 - 50 Very Good
50 - 100 Good
100 - 350 Fair
350 - 1000 Poor
1000 + Very Poor

So I got this thing and plugged it in in my basement and let it settle for a half hour or so. I had not used any tools for at least 24-hours.

On returning to the shop, it was reading 53/4. You have to add "00" to the end of the readings, so 53/4 translates to 5300 particles total (per cubic foot), with 400 of them being larger than about 5 microns. So far, so good (looking at the table my reading was considered good).

So I switched on the vac and started to cut some MDF. I basically cut the edge off a 3/4" thick piece of 24" long MDF, taking about six swipes. This type of cut (where the blade isn't buried in the wood but rather the left edge of the blade is exposed) seems to generate the largest amount of visible dust above the saw.

I then switched off the saw and watched the meter spike. Approx. one minute after I was done cutting, the meter hit a max of 1955/515. So 195,500 particles (down to 1-micron) and 51,500 larger than 5.0 microns. Nearly twice the 1000+ reading that garners a "poor" rating from their table.

Subsequent readings:
+3 minutes (from peak): 1001/223
+9 minutes (from peak): 499/91
+46 minutes (from peak): 54/2 (now, it could have been low for a while, I had to go upstairs and wasn't paying super-close attention to the meter).

I'm taking for granted that the meter does, in fact, measure down to under 1-micron. However, I will say that the meter is extremely sensitive. Just moving around in the area (within six feet of the meter) causes readings to climb.

Some interesting factors: Above the saw is a vent from the furnace. The furnace has a Honeywell electronic air cleaner. When I close this vent, and let the [new] fine dust air cleaner (down to .3-micron) filter run for just fifteen or so minutes, the meter gets down to 18/1. With the vent reopened the meter almost immediately climbs to 50ish/3-4ish. So my take on this is that, with the vent open, the air from the rest of the house dilutes the super dirty air the table saw creates as I cut. So after cutting the #'s peak, but then fairly quickly start to drop again.

It is too early to make any real generalizations. I hope to use the meter to improve dust collection/filtering in my shop, home, and office (where we service PC's that are full of dust--similar issues to home wood shop).

BTW, the black thing is the meter, the big thing sitting on the floor is my new fine air filter.

[D Romano]

phil,
I'm not sure how small your shop is, maybe 100 square feet? The size of the shop has a lot to do with the concentration of particles (duh) and with so little airflow to your machines, I would not be suprised if your shop is hazardous to your health. I'm not as militant about all this as Bill Pentz, (and you don't even need to ask him what he thinks about this, you could already guess) but I have become at least alot more concious of what I am breathing. A couple years after buying our fixer-upper house, I started getting migraine headaches. I never wore a mask except for when it was obvious to (can't see across the room because of the drywall dust) or if painting in a small closed room (different type of mask). I don't know if this caused my headaches, but I can imagine it was pretty unhealthy. Here's my setup:

I have a 1 car garage in the basement which is 12x23 with an 8 foot ceiling. I have an 8" jointer, planer, a contractor style tablesaw with a 50" fence and a Bench Dog cast iron router table attached to the side, a drill press, a miter saw and a small belt/disc sander. For the hand helds, I have routers, palm sanders, circ saw, jigsaw, etc.

For dust collection I have a Jet DC 1200. The bottom bag is plasctic and the filter is a 274 sq ft paper blend canister from Wynn environmental. I plan on adding a second one to it. It's a good deal for 90 bucks. Inside I made a flapper to dislodge dust build-up. (hopefully this will be a lot less with your baffle design) I run 6" ducts wherever I can. Currently, I have a the 12" mitersaw mounted over a down draft hood and my jointer hooked up to it. I can run a 4" flex hose to my planer when I use it and will soon enclose the underside of my router table and hook up the 4" flex hose to that.

For other tasks, such as the top of the router table, I have a shop-vac and a Oneida Dust Deputy. I works great. A shop vac is nearly useless in a wood shop with some sort of preseparator. I also use this for my palm sander and when I have the patience, for the hald held router.

Finally, for ambient dust, I have a Jet air cleaner hanging from the ceiling, the 1000 cfm model. I operate it on HIGH and I try to wear a good quality N95 dust mask, the kind with a little respirator and nose crimp. I think it it is a 3M #8511. I wear this because I can't tolerate the air cleaner being on the whole time, it makes too much noise, so when I turn it off, I'm still safe.

Bill Pentz would probably frown at this, but I use a my nose and a tissue to tell me how clean my air is. After all day in the shop, I'm still clean if I've got either the air cleaner or the dust mask on. Hey, when I work outside raking leaves or digging, or mowing the lawn I'm breathing in a lot more crap that this.

I found some info on that particle counter, http://www.hvac-talk.com/vbb/archive/index.php?t-150973.html and it seems like a good product. Can't believe it goes for only $149. Your Shop Fox air cleaner is too small for your shop, get a dust mask.  Also try to use less MDF, that stuff is really just pressed powder and glue to begin with.

-David

[phil (admin)]

David,

I'm kinda going in a different direction with this.  First, the purpose of my test was to determine whether there was a real, lingering health hazard of having a woodworking shop in the basement.  I have satisfied myself that just a few minutes after machining, airborne dust levels return to levels that I won't say are "safe," but which aren't too different than you'd find outside or in your office (1/6th of what you'd fine in downtown L.A., for example).  That is taking into account particles down to approx. .8 or .9-microns.

The purpose of the .3-micron filter is to track longer-term generation of sub 1-micron particles.  That is, what happens when I run it for two weeks in my shop basement.  What will the filter look like.  How much will the CFM drop (it gets 195-CFM according to my measurements when fan is on high).  Now what happens when I take it to work and repeat the experiment?  How much different will the filter look?  How much less (or more?) will CFM drop?

I'm still in the quantifying stages and I'm going to resist making any changes until I know where I actually need them and can determine how much they will contribute to improving any problems I identify.

Keep in mind that BP's own testing of shops (even those w/ his cyclones) found that they all failed.  Within minutes of machining MDF I believe every single shop that was filtering indoors (and not exhausting shop air) saw their #'s climb approximately the same as mine.  I believe some of these shops had the same type of high CFM air filter as you have.  And some have found the higher CFM air scrubbers exacerbate the problems unless they filter to under 1-micron.  I have to read his tests more carefully, but I believe only shops that open their doors and blow their air outside were able to stay within the parameters he (BP) was seeking.

In my case, I greatly benefit by the Honeywell electronic air cleaner (it is a hole-house air cleaner attached to the furnace).  I have heard people rave about these, and others disparage them.  In my case, my unit is blowing air in the 20's (meaning 2000 particles .8 or .9 microns and up).  This is extremely clean air.  I have always suspected it works well because even with all my kid's pets, our plush carpeting, and our lifestyle, our house requires less dusting than any other house I've been in.

There is a HVAC vent right above the table saw that is constantly on (the fan on my HVAC equipment is always running which is what is recommended when you have an electronic air cleaner).  This is constantly dumping clean air into the shop, which means the recovery after machining MDF (I don't use a lot of this) is pretty quick.

My gut tells me the thing that would improve my #'s most would be the additional of a Shark Guard w/ dust port on top of the saw.  But like I said, I'm going to run the meter and the .3-micron filter for a while and get a good baseline before I make any changes.

[D Romano]

Phil,
It sounds like your shop is alot cleaner than I was thinking, but is the whole whole filter doing the brunt of the work? I thought the only ambient air cleaner was the small Shop Fox one. Is the Honeywell getting clogged up when you use the shop? If you don't mind me asking, how clean is your tissue?

You are correct about BP's findings. He seems to be saying that it is impossible, in a hobbyist environment, to control the dust to the degree he claims is necessary.

David

[phil (admin)]

Phil,
It sounds like your shop is alot cleaner than I was thinking, but is the whole whole filter doing the brunt of the work? I thought the only ambient air cleaner was the small Shop Fox one. Is the Honeywell getting clogged up when you use the shop? If you don't mind me asking, how clean is your tissue?

You are correct about BP's findings. He seems to be saying that it is impossible, in a hobbyist environment, to control the dust to the degree he claims is necessary.

David

I've only done limited testing, so I'm not going to go out entirely on the branch and insist the electronic air cleaner is the key to my success.  After all, I only cut 12 linear feet of MDF.  I have to do more testing.

If I don't wear a mask and work in the shop for a couple hours and use MDF and hardboard, well, my tissue says as much (if you know what I mean).  If I am working with hardwoods and wear the mask when I'm performing operations that create lots of fines (hand sanding, for example), then I'm fine.

More testing is really required.  It looks like some other WWers are going to order the meters and it will be interesting to read not only their results, but I'm sure countless ways they'll figure out how to improve (lower) their #'s, too.

[AljonGuzman]

             What will be your conclusion at the end of your analysis? May i know?


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Programmable Thermostats

[AirerZer]

                 Yeah  I think the conclusion that you talking that you are asking is not yet finish..,AM i right?


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aprilaire