> PMfine can be controlled. Not all control devices are equivalent to
> chickenwire. HEPA filtration, electrostatic precipitators, etc all
> achieve various measures of control of fine particulate matter.
To some extent, certainly. But none of those things are "shop vac bags".
And since EPA tests do not even recognize respirable particles as a separate
size range, they don't tell us much about how effective those devices
actually are at reducing the dangerous particles, as opposed to the
particles that do not cause silicosis. Don't forget, the EPA's smallest
particle category includes particles 10 times the size of those that cause
silicosis. What they are measuring is how much gravel the chickenwire will
stop, not how much sand.
> Effectiveness varies, and is typically directly related to the cost of
> the control device.
Just curious, how many $1000 shop vacs have you seen in home shops ? The
home versions of the filters you mention don't come close to flowing the
amount of air that an ordinary shop vac does (not to mention that they're
really lousy at removing sub-micron particles).
> Furthermore, a closed loop system has no emissions.
Only if you never open it. A sand blast cabinet where you can't take the
parts out afterwards would be singularly useless.
> In the case of sand blasting, closed loop systems are easily utilized.
Care to offer an example ? I have never seen a sand blast cabinet that was
hermetically sealed, seems to me there are certain operational difficulties
with that, not to mention the cost.
> The effectiveness of dilution in reducing exposure to toxic materials
> is well known and documented.
Sure. If you breathe x cubic feet of air and it only has 10 particles per
cubic foot, then you've breathed a lot fewer particles than if it contains
1,000 particles per cubic foot. That doesn't contradict anything I said.
> Distance creates dilution, dilution reduces exposure,
> reduced exposure reduces risk.
Great. So instead of dying of acute silicosis next year, I can live to be
100 and only have chronic silicosis. This planet is not infinite, nor is
it's atmosphere. You can only go so far diluting pollutants before you've
run out of clean air to dilute them with. Living in Los Angeles makes this
abundantly clear.
And in this case, there is a simple, inexpensive way to avoid creating the
pollutant in the first place.
> Nolan Penney
> Air Toxics Section Head
> Maryland Department of the Environment
Does your boss know that you're telling people it's OK to generate
respirable silica particles and blow them into the air because you can't get
silicosis from beach sand ? Good thing I'm not a Maryland tax payer ...
Randall
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