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U.S. Environmental Protection Agency	2006-P-00017
^	1 Office of Inspector General	March 22'2006
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At a Glance
Catalyst for Improving the Environment
Why We Did This Review
We sought to determine
whether the air emissions
factors used by the
Environmental Protection
Agency (EPA) are of
acceptable quality for making
key environmental decisions,
and whether EPA's process
for developing, improving,
and rating emissions factors
is sufficient to meet users'
needs.
Background
Emissions factors are broad
estimates of the emissions
generated from a source, such
as a factory. Nationally,
emissions factors are used for
about 80 percent of emissions
reporting. An emissions
factor is a representative
value that attempts to relate
the quantity of a pollutant
released with an activity rate
associated with the release.
Emissions factors underlie
many environmental
decisions. Recently, States
and industry have been
developing emissions factors
and submitting them to EPA.
For further information,
contact our Office of
Congressional and Public
Liaison at (202) 566-2391.
To view the full report,
click on the following link:
www.epa.qov/oiq/reports/2006
/20060322-2006-P-00017.pdf
EPA Can Improve Emissions Factors
Development and Management
What We Found
EPA has made progress in emissions factors development since our review of the
program in 1996, but a large number of factors continue to be rated low. The
number of EPA-rated factors increased by nearly 94 percent, from 8,838 in 1996 to
17,110 in 2004. However, the percentage of emissions factors rated below average
or poor increased from 56 percent in 1996 to 62 percent in 2004.
Emissions factors, intended for use in developing emissions inventories, have been
inappropriately used for key environmental decisions beyond their intended use.
For example, emissions factors have been used for non-inventory purposes, such as
setting permit limits and reporting the level of air pollution control at specific
facilities. For three industry sectors EPA examined, inappropriate use of emissions
factors contributed to more than one million tons of pollutants not being controlled.
Demand for emissions factors is increasing, and will continue for a broad array of
environmental decisions, including measuring and reporting environmental
progress. This pertains not only to existing factors but to those that still need to be
developed, especially emissions factors for sources of fine particulate matter. If
EPA can improve the quality of its factors, this should improve environmental
decision-making for reducing air pollution. Improving the quality of emissions
factors is an extremely challenging task that may take EPA years to address.
The quality of many emissions factors remains low in part because EPA did not
have a sufficient process for developing, improving, and rating emissions factors,
nor did EPA have a comprehensive strategic plan. We found inconsistent
emissions factors guidance, continuing reliance on a qualitative rating system when
a quantitative range of uncertainty is needed, and insufficient program funding
when needs are increasing.
What We Recommend
We are making a number of recommendations to EPA to, among other things,
develop emissions factors guidance that addresses the development and appropriate
use of emissions factors for non-inventory purposes; establish a rating system that
provides the quantitative range of uncertainty for emissions factors for both
inventory and non-inventory purposes; work with industry, State and local agencies,
and others to leverage available resources for meeting increasing demands for new
factors; and establish a workgroup to develop a comprehensive strategic plan for the
Emissions Factors Program, and ensure that requested resources are used to achieve
program goals. In response to the draft report, the Agency stated that our
recommendations generally align with its current improvement efforts.

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