MDF safe dust mask at WWW

[ClintO]

At one of the seminars on Saturday Les Miller mentioned dust maks that were MDF safe. Has anyone heard of these. I want some protection but dont want to wear a full face respirator style mask.

The Carbatec catalogue has some dust masks from 3M- are these any good?

CLint

[Eastie]

Clint,
I can’t quite find my bargepole – so I’ll answer it as best I can.

Ok – to deal with the 'MDF safe' statement there are any number of respirators that are capable of protecting you from MDF dust. A scientific committee run by the UK’s Health and Safety Executive conducted a major investigation into the toxicity of MDF dust over the past couple of years. The committee endorsed the conclusion of the hazard assessment that “there is no evidence that the ill-health effects associated with exposure arising from the machining of MDF are different from those associated with similar exposure arising from machining other forms of wood”.<SUP>1</SUP>

Whether or not a 3M or other half face respirator with a P1 or P2 type filter will be sufficient protection depends upon the airborne concentration of dust – if it is well above the exposure standard (1 mg/m<SUP>3</SUP> air for hardwood and 5mg/m<SUP>3</SUP>) the under Australian Standards you would need to go to either:

a full face mask with appropriate filters, or
a full face mask with positive air supply (i.e. the likes of the triton unit), or
a half face respirator with an air hose to a remote clean air supply.
Historically airborne dust monitoring within professional workshops has shown that two in three workshops do not have sufficient dust controls in place to keep the level of dust below the legislated safe exposure standards. Of these it is not uncommon to see exposure as high as ten times the safe exposure standard. In Australia WorkSafe Australia has legislated the maximum safe wood dust exposure of 1mg/m<SUP>3</SUP> air for hardwood and 5mg/m<SUP>3</SUP> air for softwoods. From previous sampling experience it is relatively easy to generate 50mg/m<SUP>3</SUP> (ten times the softwood exposure standard) and dead easy to exceed 10mg/m<SUP>3</SUP> for hardwoods with either a circular saw or a random orbital sander (without dust extraction).

Australian standard AS 1715 gives guidance on the selection of appropriate protection, and the part that deals with selection of appropriate protection includes the following equation:

Required minimum protection = ambient airborne concentration / acceptable exposure standard

I’ll do a scenario for both softwood and hardwood:

Lets take ambient airborne concentration for both hardwood and softwood at the high end = 50 mg/m<SUP>3</SUP>

Acceptable exposure standard = 1mg/m<SUP>3</SUP> for hardwood, 5 mg/m<SUP>3</SUP> for softwood

Required minimum protection (softwood) = 50/5 = 10
Required minimum protection (hardwood) = 50/1 = 50

These figures relate back to a table in AS 1715 which specifies protection levels, with the higher the result of the calculation the higher the required protection level (see attachment)

For softwood, a P1 or P2 filter in a half face mask with replaceable filters or a disposable mask would be generally considered adequate, as would a positive air powered respirator with a P1 type filter and head covering. (i.e. the likes of the triton helmet).

For hardwoods, it steps up a notch and a full face mask with P2 filters or alternatively a full face positive air powered respirator with hood and P2 filters, or a half face mask with a continuous flow supplied air line would be considered appropriate protection under all but the harshest of circumstances.

The reason for the difference between hardwood and softwood being the higher toxicity of hardood dusts and the listing of hardoowd udsts as carcinogenic.

Whether or not you subscribe to all this technical stuff or not it's safe to say some protection is better than none. Also, the better option is to control as much dust as possible at the source.

From a personal point of view I try to keep dust to a minimum by extraction/vacuum and use a survivair silicone half face mask with removable P2 filters which is fairly economical to setup and run and I find it far more comfortable to most of the the rubber and pvc face masks that you see covered in dust at hardware shops.

Cheers,
Mark
(safety and soon to be wood dust guru ;) )

References:
1. http://www.hse.gov.uk/wood/pdf/woodn16.pdf

[craigb]

Mark,
How is the airborne dust particle concentation measured. I suppose they have some machine to do it?
Is there any low tech way to do it that I could use in my workshop?
I try to keep the dust down as much as possible but it would be interesting to find out how sucessful I've been.

Craig

[Eastie]

Craig,
Normal sampling is done with a sampling pump and a small cartridge filter with a membrane that captures dust before it enters the pump. Pumps can either be put in the workplace or you can get workers to wear them, with the sampling head fixed to the workers collar or shirt pocket which gives you a personal exposure reading. The pumps are calibrated thus the volume of air can be calculated for a sampling period and the filters are weighed before and after sampling to see how much dust was captured. These two figures you can calculate mg/m3.

There is a crude diy method that gives you an idea of your risks - it's in the link below - again from the HSE. The main feature of the lamp bulb is the spot beam as opposed to a flood beam. This method doesn't correlate to actual exposure and is mostly used to assess the effectiveness of extraction systems.

Cheers,
Mark

http://www.hse.gov.uk/pubns/wis12.htm

[craigb]

Thanks for that. After just getting my workshop rewired, I now have very good lighting so the airborne dust should show up. I find the worst dust creator is the SCMS. That's about the only time I'm seeing airborne particles. I got the sparky to install an exhaust fan when he did the wiring job and I tend to run that all the time when I'm using the machines, which are hooked up to a DC of course ;) but not a cyclone as I don't have the room.

Any time I'm going to be doing anything that is going to create large amounts of dust, I use the Triton respirator. Otherwise, I tend to use a paper mask as I don't find the Triton very comfortable to wear.

Cheers
Craig