# Why Do I Need Air Filtration?



## Holubec37 (Oct 28, 2017)

How much would I benefit from an air filtration system?

My workshop is a standalone 16×24 building. I'm curious to know if by adding a ceiling-mounted air filtration system, just how much cleaner my shop would be. Right now, I carry my mitre saw and table saw outside to eliminate dust buildup inside. The weather is a big variable in what types of equipment I get to use. I'm also planning on setting up a dust collection system such as a Dust Deputy or something similar so that I can leave the doors closed and turn on the AC/Heater depending on the season and outdoor conditions.

I see alot of reviews of these systems, but cannot really find answers to my questions about the performance. I do understand that they are not replacements for dust collection systems.

Do you run them while you're running equipment, and then leaving them running for a period of time after you are done? This is just one of many questions I have. Most reviews of these systems (that I have come across) are just unboxings and how they mount them.

Any and all information regarding these systems would be appreciated. What have you learned from your experience with them?


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## JRsgarage (Jan 2, 2017)

i usually scrub the air randomly throughout and turn it on for couple hours at end, after work for day is finished. i would want both dust collector and an air scrubber in any shop.


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## wapakfred (Jul 29, 2011)

I don't see them as useful for health reasons, but they are really good for generally trapping more of the fine dust in the shop air. They are especially useful if you don't have a separate finishing room, the one I had (shop built) would clean the shop air really well in about 4 hours. It also reduced the buildup of the fine dust layer around in the shop. But for your lungs, by the time the filter gets it it's already in your lungs….at least that's the way I see it.


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## richardchaos (May 12, 2017)

I to have a tiny workshop. I even have to wheel two of my bigger machines out to under the cars port that I don't use very often to have enough room.

I deal almost all the time with PINE. and other softwoods.

I consider a Air filtarion system a LUXURY. If you are worried about breath stuff in as opposed to a clean safe shop I would wear a mask. I would suggest a Hilary Clinton one.

NOW ifI was doing high end ward wood furniture that requires a perfect finish I might have one swell. TRUST me I do get dust dirt and grime in some of my finishes but again its a luxury to me.

ALSO is everything in your shop on WHEELS like mine are? ALSO why are good casters so damn expensive. I mean hasn't the WHEEL been around for like a million years



> How much would I benefit from an air filtration system?
> 
> My workshop is a standalone 16×24 building. I m curious to know if by adding a ceiling-mounted air filtration system, just how much cleaner my shop would be. Right now, I carry my mitre saw and table saw outside to eliminate dust buildup inside. The weather is a big variable in what types of equipment I get to use. I m also planning on setting up a dust collection system such as a Dust Deputy or something similar so that I can leave the doors closed and turn on the AC/Heater depending on the season and outdoor conditions.
> 
> ...


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## bondogaposis (Dec 18, 2011)

Do you run them while you're running equipment, and then leaving them running for a period of time after you are done?

I turn mine on when I enter the shop and leave it running for 1/2 hour after I exit. It pulls a lot of fine dust out of the air, the stuff you can't see but will be breathing if you don't have anything.


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## Gilley23 (May 9, 2017)

It's woodworking, you're going to be making dust with dang near everything you do. With that, you want to capture as much of the dust as you can before it has the chance to be spread around the air….i.e. catch it right at the source. For me this is a Harbor Freight dust collector attached to the side of my table saw and shop vacs that automatically turn on with individual machines.

You also want to be able to not just move air around, but actually exchange it with fresh air. I use a ceiling mounted air scrubber as well as a conditioned ventilation system. By that I mean I'm using my garage as a workshop and my AC unit pulls fresh air in from the multitude of air leaks that are in there.

Works for me. It's not perfect by any means, but it's good for what I'm doing. I still have to take the planer outside to use it, I don't have that collection for that.

Run the scrubber while you're in there and then for a little bit longer after you leave.


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## a1Jim (Aug 9, 2008)

Maybe not the way many shops are but the best situation is to capture dust before it's in the air by that time it's really to late to gain any health benefits from adding a ceiling-mounted air filtration system unless you can turn it on and let it run for some time.


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## Andybb (Sep 30, 2016)

*#1 reason* - *Even using a dust collector I know it's helping. If I am cutting something that is red like padouk a half hour after I'm done there is a red tint on the filter, which means I would be breathing that and MDF and other nasty fine stuff. Even with the doors open and the fan on, if I spray rattle can paint the filter tints to that color. *

2. Happy wife happy life. My wife calls my shop a 2 car garage and even with a fan blowing out the fine dust ends up in the house, on the car and in the car if a window is left open. Not an issue for you but it is for a lot of us.

I originally bought it for reason #2 not knowing that reason #1 was even happening. That was a "holy s**t" moment for me when I saw the red padauk in the filter. I probably should always wear a mask but I know I won't but I do when I'm cutting stuff like that.

For me, moving tools outside is a pain and an inefficient use of time. I like to be able to move from one tool to the other even though I have everything on wheels.

I bought a Wen off of Amazon. It has a remote and a timer on it. I try to remember to turn it on then set the timer for 2 hrs when I'm done and forget about it. Well worth the $99 bucks on sale IMO. So quiet that I sometimes forget it's on.

It really doesn't do anything to help keep the shop clean. I just sweep and also use a leaf blower every few weeks. Using a zero clearance insert doesn't help plus I use a big shop vac system so I don't have the huge suction like Loren does.


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## Loren (May 30, 2008)

I have one and I don't use it much and even 
if I did I don't think it would keep the shop
much cleaner.

I have a second dust collector outside the shop
and sometimes I put on a mask, blow all over
the place with compressed air, turn on the dust
collector, put the hose in the shop and roll the
door down. It's a big dust collector and it 
sucks that airborne dust out pretty quick.


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## jmos (Nov 30, 2011)

I've got a good dust collection system (ClearVue 1800) and a ceiling mounted air filter (Powermatic) with Wynn filters. I always use the dust collector, but only turned on the air filter when I was doing things that I figured kicked up the most dust. I've been working this way for about 5 years.

I recently decided to buy a Dylos meter, with the extended lower particle size range, just to get some data on what was really going on. While I'm not going to argue it's 100% accurate, I think it does give a good relative sense as to what's going on.

What I discovered -

On the good side: The dust collector really does do a good job in most cases when I'm using my large equipment. When sanding, I use a homemade downdraft table and the dust port on my Porter Cable sander; I used to wear a respirator, but discovered that the dust levels were really quite low. I can also use the dust collector to filter general dust out of the air, as Loren mentions above, and it works pretty quickly.

On the bad side: Sweeping up REALLY kicks up dust; highest levels I ever see. However, just moving around in the shop working kicks up dust, and at high enough levels to worry about. I now run my air filter the entire time I'm in the shop, and it does help keep the dust level down. This surprised me, but was a good lesson.

So, my takeaway, capturing dust at the source is always best, but the ceiling mounted air filter is a worthwhile device and should be used.


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## Manitario (Jul 4, 2010)

Ambient air filters slowly reduce the dust in the air over a period of time; while they are reducing the dust load, you're breathing it in. The best solution is to capture dust at the source before it gets into the air


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## Carloz (Oct 12, 2016)

I have a Jet air filter and leave it on for 4 hours after I leave the garage. It makes a huge difference. If I forget to turn it on I have a thin film of dust on everything by morning.I would seriously question someones claim above that half hour makes any noticeable difference.


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## Holubec37 (Oct 28, 2017)

Thanks everyone for the input. My next question would be the orientation of the system when mounted from the ceiling. Is it best to just mount in the middle, or more towards the end with the most dust generated?


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## jonah (May 15, 2009)

It's usually best to mount it nearer to a wall to get a sort of swirling air circulation going. Mounting in the middle is less effective.


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## clin (Sep 3, 2015)

I run mine more or less anytime I'm in the shop. Even if not making dust, just moving around the shop kicks up the dust that is there. The most harmful dust is invisible floating in the air. I have a Dylos air particle counter and it is interesting to see how the dust count goes up while moving around the shop and doing things. Of course, this is less an issue the cleaner the shop. But unless you've recently mopped the floor and wiped down bench tops etc, there's dust.

I agree, best to capture at the source, but I see a room filter not as either or, but rather something extra. It certainly helps keep the shop cleaner. As the dust trapped in the filter would otherwise be dispersed around the shop. Will it mean you never have to sweep. No it doesn't. Dust settles pretty quickly and unless you have something constantly stirring ALL the air in the shop, the room filter won't get it all. But it will clean all the air over time.

Most of the time, 15 minutes or so reduces the dust count by a large amount. This of coruse depends on the CFM rating of the filter, the size of the shop, and how high the dust level is to start.

I run mine while cutting and at least 30 minutes after before taking off my respirator. Though often I'm making many cuts so it's just on all the time. I still wear a respirator until I see the particle count is low. Mine has a timer and I run it the minimum of 2 hrs when I leave the shop. It's common my particle count will get down to 0 when I do this.

Concerning placement, I've heard placing it about 1/3 the length of the shop, with the intake on the short end. I agree with this. The intake air comes form all directions so at any given point the air speed is pretty low. So keeping the intake on the short side, reduces the size of the dead area. The exhaust stays more as a high speed column of air due to the momentum of the air. So this end does a better job of stirring things up.

I'm not sure I buy the idea that it needs to be to one side to create a circulation. If in the middle it will simply have circulation on both sides. Likely there is some advantage of one location over the other, but I'm not sure the suggestion of putting to the side is backed up by any actual knowledge. If so, I'd be interested in see the references.

I'd put it were it is convenient. And if to the side is convenient, then sure why not, maybe there is something to that. But I wouldn't sweat that one way or the other.


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## Finn (May 26, 2010)

I have mine mounted on the ceiling in the center of my small shop. The CFM rating predicts it to clean all the air in my shop in six minutes. And it does just that. I turn it on anytime I see dust in the air. It does not keep the floor and benches dust free but it sure cleans up the air I am breathing, and quickly.


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## SignWave (Feb 2, 2010)

I've always been skeptical of the ones that you buy and hang from the ceiling. For one thing, the filters seemed small to me, and second, having it up high seemed to be fighting gravity. I don't doubt that having one is better than not, but the effectiveness seemed limited.

When I built mine, I made it as a rolling cart, with 4 - 20"x20" filters. It sits low, so that it's working with gravity, and has about 11 square feet of filter area. And since it's on wheels, I can point it wherever I want. In the summer, my shop is very hot, so I point it at myself to get both filtered air and a cooling effect. I can absolutely tell the difference in my breathing as a result of having this filter. The respiratory issues that I used to have are MUCH better.


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## tomsteve (Jan 23, 2015)

air filtration is a very good thing. all that fine dust in the air- what gets in the lungs doesnt come out.
as for hanging, id suggest so the filter pulls air from where the most dust is generated.


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## Carloz (Oct 12, 2016)

> Ambient air filters slowly reduce the dust in the air over a period of time; while they are reducing the dust load, you re breathing it in. The best solution is to capture dust at the source before it gets into the air
> 
> - Manitario


Unfortunately it is impossible. First of all not all dust can be captured unless you shroud the whole cutting piece in a air tight enclosure. Secondly the finest dust escapes from the dust collector itself and that is where air filter come to the rescue.


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## jonah (May 15, 2009)

> I m not sure I buy the idea that it needs to be to one side to create a circulation. If in the middle it will simply have circulation on both sides. Likely there is some advantage of one location over the other, but I m not sure the suggestion of putting to the side is backed up by any actual knowledge. If so, I d be interested in see the references.
> 
> I d put it were it is convenient. And if to the side is convenient, then sure why not, maybe there is something to that. But I wouldn t sweat that one way or the other.
> 
> - clin


Years ago there was a FWW article written by an aeronautical engineer that talked about air flow and why near a wall (preferably along the long axis of the room) was better than the middle of the room. Since aeronautical engineers primarily deal in air flow, aerodynamics, and the like, I trust that he knew what he was talking about. I can't remember what issue or year I read it, but it stuck with me.


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## Bluenote38 (May 3, 2017)

> I m not sure I buy the idea that it needs to be to one side to create a circulation. If in the middle it will simply have circulation on both sides. Likely there is some advantage of one location over the other, but I m not sure the suggestion of putting to the side is backed up by any actual knowledge. If so, I d be interested in see the references.
> 
> I d put it were it is convenient. And if to the side is convenient, then sure why not, maybe there is something to that. But I wouldn t sweat that one way or the other.
> 
> ...


I remembered the same thing and challenged it using CFD (Computational Fluid Dynamics). It's kind of true IF (notice the BIG if?) there is nothing in the box (room) to disturb the flow. You get a really nice flow pattern with a central swirl/dead space like a hurricane. So do not breath the air in the middle. Like most of us though our tools occupy the outer edges of the room at varying heights. Add those into the mix and you get really ugly flow patterns. It does help the center swirl a bit though but turbulence (eddies and backflows) and dead zones (no air movement) reduce efficiency. Central placement helps with the number of dead zones and turbulence to some extent by drawing from the outer edges to the center (not totally true but a closer analogy). Machine placement and heights will affect the flow efficiency. Btw the big assumption here is that settling and suspension times are directly related to air velocity.


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## wapakfred (Jul 29, 2011)

> Ambient air filters slowly reduce the dust in the air over a period of time; while they are reducing the dust load, you re breathing it in. The best solution is to capture dust at the source before it gets into the air
> 
> - Manitario
> 
> ...


While I totally agree with your first point, I also totally disagree with your second point. A good DC filter will capture 99.x% of the dust in the air passing through it. But that filter needs to be capable of filtering particles smaller than 1 micron…...there are a LOT of DCs that won't do that.


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## Manitario (Jul 4, 2010)

> Ambient air filters slowly reduce the dust in the air over a period of time; while they are reducing the dust load, you re breathing it in. The best solution is to capture dust at the source before it gets into the air
> 
> - Manitario
> 
> ...


I sort of agree with you; however the particle count in my detached shop averages around 500ppm of dust less than 5 microns when I'm in the shop using the machinery vs. around 200 when I'm not there. In comparison, the air in my house averages around 500 ppm. So, yes, there is a small increase in dust from my machinery usage, but a trivial amount; certainly not one that having an ambient air filter would make any appreciable difference. Generally the amount of dust in my shop on top of my machines when I clean them is less than my house…

A quick review of the ambient air filters on the market (Rikon/Jet/Supermax/JDS/Powermatic/Grizzly) show that they all only filter at best to 1 micron. My DC filters are 0.3 microns…so why would I use some thing that just pumps the smallest dust around the room rather than rely on my DC?

Also, even if you had an awesome ambient air filter eg. that has smaller than 0.3 micron filtration and at least 6 air exchanges/h for the shop and didn't have a tiny filter which quickly reduces the CFM it pulls in as it gets coated in dust; it still only reduces the amount of dust in the air over a gradual time period. There was a great article in FWW in July 2010 which illustrated the time needed for an ambient air filter to reduce the dust in a small shop. While this is happening, you're breathing it in. So, it makes more sense to capture as much of it as possible before it goes into the air.


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## Andybb (Sep 30, 2016)

Back to your original questions.


> I m curious to know if by adding a ceiling-mounted air filtration system, just how much cleaner my shop would be.
> 
> Do you run them while you re running equipment, and then leaving them running for a period of time after you are done?
> - Holubec37


IMO filtration isn't going to do much to help keep the shop clean. I look at dust collection and filtration as 2 related but different things. Dust collection helps keeps the shop clean while filtration helps keep your lungs clean. If I'm in the shop (or garage as my wife calls it) the filtration is on and when I'm done if I can remember I then set the timer to run for another 2-4 hrs.

I don't need a particle detector to confirm common sense. As I said, if I can see it in the filter (especially in the 1 micron secondary filter) I know it's in the air and I am breathing it. I pick up wood scraps and put them in the trash can. I know that sweeping, walking etc. stirs up dust so I try to avoid sweeping whenever possible. I vacuum with 3 main attachments for the floor, the corners and tools/surfaces. The brush does the best job on the tools and surfaces including the walls. When I do sweep the soft broom is always in contact with the floor, so it's more gathering than sweeping. My dust collection is a DIY cyclone attached to a Shopvac with an internal HEPA bag. 
















In the summer I will sometimes keep the garage doors open and run a fan facing out to blow as much fine dust out as possible. During the winter heat is more important to me than dust so the doors stay closed.

Please don't take offense but this line of thinking makes no sense to me. 


> I don t see them as useful for health reasons, but they are really good for generally trapping more of the fine dust in the shop air. They are especially useful if you don t have a separate finishing room, the one I had (shop built) would clean the shop air really well in about 4 hours. It also reduced the buildup of the fine dust layer around in the shop. But for your lungs, by the time the filter gets it it s already in your lungs….at least that s the way I see it.
> - Fred Hargis


You are saying that there is fine dust the shop air. You are also saying that your shop built unit takes 4 hrs to clean the air of particles that settle in the finish (and your lungs) so again you are saying that there is fine dust in the air which means you are breathing it!

For a thorough cleaning every 2 weeks or so depending on how much time I have spent in the shop I will put on the respirator and vacuum everything before opening the doors and running the leaf blower. I usually run once then again after about 15 mins or so after the dust is settled (and there is always more dust).

Lets face it. Our shops are not laboratories. Labs spend millions of dollars on air filtration systems. Do I wear a respirator anytime I'm in the shop? No. It is what it is so the best we can do is try to be diligent with what we have IMO.


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## wapakfred (Jul 29, 2011)

Andy, I have t admit to not understanding your point of contention…seems to me like we said the same thing (related to my point about ambient air cleaners doing little to help your lungs).


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## Andybb (Sep 30, 2016)

I see what you're saying. I guess I'm just saying that with filtration there is a lower concentration making it into your lungs. Kind of a "every little bit helps" philosophy. There has to be less floating around because it's in the filter. I wish I could say I wear a mask any time I'm in the shop, but I don't.


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## Carloz (Oct 12, 2016)

> A quick review of the ambient air filters on the market (Rikon/Jet/Supermax/JDS/Powermatic/Grizzly) show that they all only filter at best to 1 micron. My DC filters are 0.3 microns…so why would I use some thing that just pumps the smallest dust around the room rather than rely on my DC?
> 
> - Manitario


This turns into another Sawstop vs Unisaw debate.
People who have airfilters swear by them, those who never used them argue how useless they are and how their dust collectors are better.


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## Andybb (Sep 30, 2016)

> A quick review of the ambient air filters on the market (Rikon/Jet/Supermax/JDS/Powermatic/Grizzly) show that they all only filter at best to 1 micron. My DC filters are 0.3 microns…so why would I use some thing that just pumps the smallest dust around the room rather than rely on my DC?
> 
> - Manitario


That's great for dust collection attached to your tools, but is that thing running all the time and is it collecting what's floating around over your head?


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## perfesser (Jun 30, 2017)

If you want the be all end all on dust collection and filtration. Bill Pentz is the expert. Here's the link to his info. http://billpentz.com/woodworking/cyclone/ It's detaled stuff but good.

John


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## Andybb (Sep 30, 2016)

> If you want the be all end all on dust collection and filtration. Bill Pentz is the expert. Here s the link to his info. http://billpentz.com/woodworking/cyclone/ It s detaled stuff but good.
> 
> John
> 
> - perfesser


Damn! Well, he pretty much sums it up. Maybe I should wear a respirator full time.


> *Summary
> The medical research shows the higher and longer the fine dust exposure the worse the damage. This should terrify small shop woodworkers, because OSHA testing shows most small shop workers who vent their dust collection systems inside get more fine dust exposure in a few hours woodworking than large facility workers get in months of full time work.*


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## Manitario (Jul 4, 2010)

> A quick review of the ambient air filters on the market (Rikon/Jet/Supermax/JDS/Powermatic/Grizzly) show that they all only filter at best to 1 micron. My DC filters are 0.3 microns…so why would I use some thing that just pumps the smallest dust around the room rather than rely on my DC?
> 
> - Manitario
> 
> ...


You missed the other part of my post, I really don't have much dust floating around:

"I sort of agree with you; however the particle count in my detached shop averages around 500ppm of dust less than 5 microns when I'm in the shop using the machinery vs. around 200 when I'm not there. In comparison, the air in my house averages around 500 ppm. So, yes, there is a small increase in dust from my machinery usage, but a trivial amount; certainly not one that having an ambient air filter would make any appreciable difference. Generally the amount of dust in my shop on top of my machines when I clean them is less than my house…"


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