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E-M:/ Correction Regarding Xylene ITSL

Enviro-Mich message from Jeff Gearhart <jeffg@ecocenter.org>

Please disregard my previous note regarding Xylene screening levels. 
My math was incorrect in converting the the 1 hr to 24 hour numbers.

I believe the correct, approximate conversion or scaling from 1 hour 
to 24 hours for a constant emission rate producing an an ambient 
concentration of 4400 ug/m3, 1 hour average, would be to multiply by 
0.4 (using SCREEN3 methodolgy), hence  0.4 *4400 or 1760 ug/m3  24 
hour average which is significantly higher then the new 24 hour ITSL 
of 100 ug/m3 emission limit and actually more protective.

Thanks again for those who have politely pointed this out to me!
Jeff Gearhart
Ecology Center
117 N. Division
Ann Arbor, MI  48104
(734)663-2400 x117
(734)663-2414 fx.


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