Date:	 July 19, 2011

Subject: 	Recommended Acute Factor for Determining Hazard Quotient for
Wool Fiberglass Manufacturing Sources

	Wool Fiberglass and Mineral Wool RTR

	EPA Contract No. EP-D-06-118; EPA Work Assignment No. 4-10

	RTI Project No. 0210426.004.010

From: 		Cindy Hancy

		Dave Reeves

To: 		Susan Fairchild, EPA/OAQPS/SPPD/MMG

The purpose of this memorandum is to provide a recommendation for the
acute factor that should be used in determining the hazard quotient (HQ)
for the risk associated with hazardous air pollutant (HAP) emissions
from  wool fiberglass manufacturing  facilities.  This work is being
performed as part of the residual risk assessment for facilities that
are subject to the National Emission Standards for Hazardous Air
Pollutants for Wool Fiberglass Manufacturing (40 CFR 63, subpart NNN).

	To determine an appropriate acute factor, RTI compiled data on plant
production capacity for the 30 wool fiberglass manufacturing  plants
currently in operation.  These data were provided in the responses to
the section 114 information request completed by the wool fiberglass 
industry in 2010.  RTI compared those annual production capacities to
the annual production rates used to determine the HAP emission rates for
the residual risk modeling that was performed earlier in April 2011. 
RTI calculated a plant-specific acute factor as the ratio of plant
production capacity to the modeled production rates.  Most of the
plant-specific factors for the melting furnaces ranged between 2.0 to
2.8.  Based on these results, and to allow for additional uncertainty in
emissions, RTI recommends an acute factor of 3.0.

	Please note that, because the production data used in determining
plant-specific acute factors have been claimed as confidential business
information (CBI) by the respective companies, we are submitting the
spreadsheet used to calculate the plant-specific factors separately
through EPA's CBI Office.

