CLEAN HEALTHY AIR: Your Feedback Requested: Annual Emission Inventory Reporting Thresholds and Accuracy | Air Quality Division

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Air Quality Division
Request for Stakeholder Input on 
Reporting Thresholds and Accuracy Levels
For Annual Emission Inventories

Arizona Department of Environmental Quality, Air Quality Division, seeks your input to determine appropriate reporting thresholds and accuracy levels for annual emission inventories required by Arizona Administrative Code R18-2-327. 
Background

ADEQ occasionally receives requests from permittees completing emission inventory forms on the level of accuracy required to meaningfully comply with the obligations of R18-2-327 (the Emission Inventory Rule). Additionally, some permittees have expressed concern that they may be unknowingly violating the rule ???? if they fail to account for a small emission point that only operated for a short time or that the burden of accounting for these low emitting sources is inordinate with their impact to air quality. 

ADEQ recognizes that all numerical data has two distinct parts:

(1) the magnitude (i.e. the number)

(2) the accuracy.

For example, 4.5 tons, 4.50 tons, and 4.50000 tons are identical in magnitude, but differ in accuracy.  While R18-2-327 identifies that the magnitude of emissions must be reported, it does not specify the accuracy with which it should be reported.

 

Consequently, ADEQ considers it appropriate to set a level at which it considers emission inventories accurate. Ideally, every permitted and fugitive emission point should be reported; however, there is a point of diminishing return in evaluating every source and potential source, no matter how small the emission rate.  Furthermore, ADEQ’s mission of protecting human health and the environment is not furthered by accounting for these extremely small sources or excessively accurate emissions reports.

Request for Stakeholder Input
ADEQ seeks your input on one or both of the following topics:

• Appropriate Reporting Threshold: Rule 327 requires facilities that emit over 2.5 tons per year facility wide to report all emissions, which could be interpreted as requiring reporting for all emission units, no matter how small the emission rate. 
• For example, a permitted source could be found to be violating Rule 327 if they failed to account for an emission source that emitted less than 0.1 lbs over the previous year.  At what point should ADEQ consider emission units to be de minimis?
• Appropriate Accuracy Threshold: For emissions that are reported, Rule 327 does not specify an appropriate accuracy level.  
• For example, should a source be expected to report 50 tons per year or 50.07 tons per year or 50.074 tons per year?  At what point should ADEQ consider the result of an emission calculation accurate?

Please address your comments to:
Michael Burton, Environmental Science Specialist III, Burton.Michael@azdeq.gov 602-771-4562 

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QUESTIONS? Michael Burton Burton.Michael@azdeq.gov 602-771-4562 Contact Us

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