Date: Tue Apr 27 1999 - 08:23:04 CDT
Attached is a question and my response regarding opacity regulations.
I have just read your e-mail on opacity. You seem to be well informed on the
subject. I am not. In fact, I am not sure what it is that you are talking
Could you give me a quick description of opacity in the printing industry and
where and why it is being controlled.
Essentially, opacity is a term given to any pollutant that produces a
visibility problem. Opacity regulations are one of the oldest types of
regulations that have been put on the books. Its purpose is to cut down on
the amount of dust, soot, and other forms of particulate matter (e.g.,
condensable organics) being released into he atmosphere. Dust, soot, and
particulate matter cause haze and visibility problems. Remember in the 1940'
and 1950's pictures of Pittsburgh's sky being black at noon? This is why
opacity regulations were adopted. In fact, the first opacity regulations were
adopted in the 1960's in Pittsburgh. Depending upon the composition of the
dusts, soot and other PM, they can cause respiratory problems and damage
Opacity regulations are usually expressed as a "percentage blockage" over a
specific time period and exclude any water vapor. Some state/local air
pollution control agencies will specify a 0% opacity limit, although this
stringent of a limit is not common. In Pennsylvania, a facility is not
allowed to emit visible air contaminants in such a manner that the opacity of
the emission is either the following:
1) Equal to or greater than 20% for a period or periods aggregating more than
three minutes in any one hour.
2) Equal to or greater than 60% at any time.
Please email with any more questions.
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