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Article # 0053







A facility that releases pollutants into the air in the state of Texas is required to obtain authorization.  The authorization includes a quantification of air pollutant emission rates from each emission source or point located at the facility.  These “authorized air emissions” are considered normal operating emissions.  The authorized emissions do not include emissions from unscheduled or unforeseen events.  For example, a small spill of organic liquid from a storage tank is not normal operation, but an unforeseen event that could cause air emissions from evaporation of the organic liquid into the atmosphere.  These emission episodes are termed “emission events” and require quantification to determine if they need to be immediately reported (a reportable quantity) to a regulatory agency as a “reportable emissions event” or simply quantified and included in the Annual Air Emissions Inventory along with actual emissions from normal operation.


The specific definition for emissions event and reportable emissions event from Texas Administrative Code of Regulations is as follows:


Emissions event - Any upset event or unscheduled maintenance, startup, or shutdown activity, from a common cause that results in unauthorized emissions of air contaminants from one or more emissions points at a regulated entity.


Reportable emissions event - Any emissions event that in any 24-hour period, results in an unauthorized emission from any emissions point equal to or in excess of the reportable quantity as defined in this section.


The environmental manager at the site must use information collected by process and operating staff that work in the field to assess the “event” to determine if it requires evaluation as a potential “emissions event” and to quantify the emissions as necessary to determine if the emissions exceeded a reportable quantity or RQ for the specific contaminant (e.g., benzene) or mixture of contaminants (e.g., gasoline) released.  Companies are free to design their own communication and examination processes as long as the system in place will result in meeting the State regulatory requirements for evaluating and reporting events.  The state of Texas currently requires that a reportable emissions event (a non-authorized air emissions release above reportable quantity) be quantified and reported within 24 hours of the event.  This short response time is necessary for environmental management, communication and possible local remediation in the case of large RQ of very hazardous materials.  The short response time means that the environmental manager must have a system of communication in place such that persons working in the field immediately report all potential emissions events no matter how small or seemingly insignificant.  Most facilities have an event or incident report form (electronic or paper) used for collecting information in the field necessary for the environmental manager to assess the situation.  The form would be immediately filled-out in the field and electronically distributed to the manager (for example, by electronic mail) and other key staff the manager or key persons contacted by telephone to confirm the information was transferred.


The type of information on a field level incident or emissions event form might include the following:



Additional information that might be included if known (if this information is not transmitted the manager would collect as part of his investigation and report):



The environmental manager would use the above information to quickly estimate the chemical species (e.g., benzene) and mass (in pounds) of air pollutant released to determine if the release was above reportable quantity (RQ) and thus requires reporting to the regulatory agency(s).


Determining if the Air Emission Release is a Reportable Quantity (RQ)


Once the release has been identified (specific chemical or chemical mixture) and the environmental professional has correctly estimated the mass of air emissions released, then it is necessary to determine if the release is above the chemical’s or chemical mixtures RQ to see if the release is a reportable emissions event and thus should be relayed to the environmental agency(s).  If the mass of the release is less the RQ it still requires estimation and documentation.  The amount of emissions should be also be included in the next Annual Emissions nventory along with normal operation emissions.


The determination of whether the release is above its RQ may be the most complicated task because the definition of a chemical’s RQ is long and complicated by the fact that it crosses both federal and state (and possibly local) definitions.  That is, some chemicals may be “reportable” under state regulations, but not reportable under federal regulations or vice versa.  Also, the magnitude of the RQ in pounds may differ for the same chemical between the federal, state and local agencies.   The state regulatory agency in Texas has codified a definition for RQ under their general definitions section in 30 TAC 101.  The definition is currently a couple of pages in length.  The definition is subject to change and should be evaluated for change often. The procedure below provides guidance in assessing a potential reportable emissions event, interpreting Texas' current definition of RQ and how to file a report if the event is above RQ.


Procedure for Assessing and Reporting an Emissions Event in the State of Texas


Question: When do I need to use this guidance document?


Answer: Every time recordkeeping or other evidence indicates that your facility may have either:


1. Emitted pollutants for which you do not have authorization (via an air permit, for example)


2. Caused emissions exceeding authorized levels (emissions greater than emission rates shown in the Maximum Allowable Emission Rates Table of your permit, for example).  Unscheduled break-downs in emission control equipment and spills are two examples of circumstances that may cause an emissions event.


Question - What am I required to do?


Answer – Follow this step-by-step procedure to determine any records or reports that you may need to create.


Step 1: Determine if the emissions event is reportable. This must be done within 24 hours of discovery of the event. If the event is reportable, the initial notification must also be filed within 24 hours.


Step 1.A: Estimate the quantity of emissions of each chemical involved in the event. If possible, use calculation techniques previously utilized for the same facility in permit applications, PBR applications or Emissions Inventory submittals. Common process knowledge, past engineering analysis or test results are good sources of data. If the release is of a mixture of chemicals and the relative amount of each chemical cannot be determined, use the total amount of the mixture as the amount of emissions for each chemical.


Step 1.B: Determine the reporting threshold for each chemical emitted. The threshold for a chemical is the lowest one that appears in the three following lists. If the chemical does not appear on any of these lists, the threshold quantity is 100 lb.





Chemical RQ (lbs)

acetaldehyde 1,000(1)

butanes (any isomer) 5,000

butenes (any isomer,

except 1,3-butadiene) 5,000(1)

carbon monoxide 5,000

decanes (any isomer) 5,000

ethanol 5,000

ethylene 5,000(1)

hexanes (any isomer) 5,000

Isopropyl alcohol 5,000

mineral spirits 5,000

nitrogen dioxide 100(3)

nitrogen oxide 100(2)

octanes (any isomer) 5,000

pentanes (any isomer) 5,000

propane 5,000

propylene 5,000(1)

toluene 1,000(1)


Notes to above table:


(1) The RQ in the Houston/Galveston (HGA) and Beaumont/Port Arthur (BPA) ozone nonattainment areas is 100 lbs.

(2) Use instead of the RQ provided in 40 CFR §302, Table 302.4, the column "final RQ"

(3) Used instead of the RQ listed in 40 CFR §302, Table 302.4, the column "final RQ" or listed in 40 CFR §355, Appendix A, the column "Reportable Quantity";


Step 2: Do emissions of any chemical from the emissions event equal or exceed the lowest of the thresholds?


Yes. The emissions event is reportable. Go to Step 3.


No. The emissions event is not reportable but you must create the required records. Go to Step 4.


Step 3: You must file the Notification for Reportable Emissions Events within 24 hours.  You can create your own reporting form that includes the information required to report under 30 TAC 101 or check the agency website for a reporting form template. E-mail or fax the completed form to the appropriate Texas Commission of Environmental Quality (TCEQ) regional office.  If there are any other local air pollution control agencies in your city or county, you must also send a copy to that office. Note that the TCEQ now requires use of their on-line STEERS system for submitting reportable emission event reports.  An e-mail or fax is considered an alternative to STEERS.  Go to Step 4.


Step 4: Create a Final Record of the Emissions Event. The final record must be created within two weeks of the emissions event and the record must be kept on site for at least five years.  If you have a reportable event and the information on the Final Record is different than that submitted in the 24-hour notification, then you should submit a revised Notification for Reportable Emissions Events Form to the TCEQ regional office and any applicable local air pollution control agency.




Jack L. Bullard, P.E. is an Engineering Partner of Bullard Environmental Consulting, Inc. He has over 20 years experience in environmental engineering, compliance, and permitting. Jack has a Bachelors of Science Degree in Chemical Engineering from the University of Texas at Austin.


Jack L. Bullard, P.E. No. 83547


Final Edition Completed December 2010



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