Exceptional Events
South Carolina Department of Health and Environmental Control (Department) operates an ambient monitoring network that measures concentrations of various air pollutants. Other environmental agencies operate similar networks throughout the United States. When an event outside human control causes an exceedance of an ambient standard, the event may be excluded from compliance calculations. There is a specific process for excluding an event, which includes public notice of each request. This notice provides an opportunity for public review and comment on the supporting documentation.
Following the opportunity for public comment, the Department submits this information to the United States Environmental Protection Agency (EPA) for their review and approval. If the EPA concurs that the appropriate flagged data were affected by an Exceptional Event, data generated by the state's monitors affected by the Exceptional Event are not used to determine compliance with the National Ambient Air Quality Standards (NAAQS).
Contact information is provided below for questions about this process or about a specific Exceptional Event proposal. Public comments on this web page are also welcome.
What is an Exceptional Event?
According to federal regulations:
"An exceptional event is defined as an event that affects air quality, an event that is not reasonably controllable or preventable, is an event caused by human activity that is unlikely to recur at a particular location or a is a natural event, and is determined by the EPA to be an exceptional event."
Exceptional Events may include, but are not limited to, prescribed burnings, wildfires, and large firework displays.
Exceptional Events do not include stagnation of air masses or meteorological inversions, meteorological events involving high temperature or a lack of precipitation, or air pollution relating to source noncompliance.
To summarize, an Exceptional Event is one that:
- Affects air quality.
- Is not reasonably controllable or preventable.
- Is an event that is caused by human activity that is unlikely to recur at a particular location, or is a natural event; and
- Is determined by the Administrator of the EPA through the process established in the rule to be an exceptional event.
What Event Documents are available for Public Review and Comment?
This area contains information on events that the Department proposes to submit to EPA for approval. Public comments are welcome on the information in this section.
There are no Event Documents available for Public Review and Comment at this time.
Prior Event Documentation and EPA Responses
This area contains information on past events that DHEC has submitted to the EPA and EPA's responses to this information.
| Pollutant | Site | Year | EPA Responses |
|---|---|---|---|
| Ozone | Congaree Bluff | 2007 | 2007 EPA Response * |
| PM2.5 | Statewide | 2007 | |
| Ozone | Cowpens | 2008 | 2008 EPA Response |
* EPA responded to both of these events in the same correspondence to DHEC.
Health Effects of Pollutants
Additional Resources
Qualifier Codes (also referred to as "Flags") are used to indicate data which are valid, but are affected by some unusual local or distant event which makes the data not representative of “normal” conditions (conditions without the event).
- Any data identified as impacted by events or operational deviations requiring qualifiers will be flagged by the Department. Requests for EPA concurrence may be submitted for data values that are, or contribute to, exceedances of the National Ambient Air Quality Standards.
- All qualifiers indicate events or operational deviations, which are not sufficient to require voiding the measurement. The Qualifier indicates to data users that the data should be reviewed for appropriate application in the intended use or analysis.
- Not all defined Qualifiers listed below are available for use with all pollutants.
| Qualifier Code | Definition |
|---|---|
| 1 | Deviation from a Code of Federal Regulations /critical criteria requirement |
| 2 | Operational Deviation |
| 3 | Field Issue |
| 4 | Lab Issue |
| 5 | Outlier |
| 6 | Quality Assurance Program Plan Issue |
| 7 | Below Lowest Calibration Level |
| 9 | Negative value detected - zero reported |
| A | High winds |
| B | Stratospheric ozone intrusions |
| C | Volcanic eruptions |
| D | Sandblasting |
| E | Forest fire |
| F | Structural fire |
| G | High pollen count |
| H | Chemical spills & Industrial accidents |
| I | Unusual traffic congestion |
| J | Construction/Demolition |
| K | Agricultural tilling |
| L | Highway construction |
| M | Rerouting of traffic |
| MD | Value between Minimum Detectable Limit and Instrument Detectable Limit |
| N | Sanding/Salting of streets |
| ND | No Value Detected |
| O | Infrequent large gatherings |
| P | Roofing operations |
| Q | Prescribed burning |
| R | Cleanup after a major disaster |
| S | Seismic activity |
| SQ | Values Between Sample Quantitation Limit and Minimum Detectable Limit |
| U | Sahara dust |
| V | Validated value |
| W | Flow rate average out of spec. |
| X | Filter temperature difference out of spec. |
| Y | Elapsed sample time out of spec. |
Glossary and Links to Acronyms
| Acronym | Definition |
|---|---|
| AA | Atomic Absorption Spectroscopy |
| AIRS | Aerometric Information Retrieval System (obsolete) |
| ANSI | American National Standards Institute |
| APTI | Air Pollution Training Institute |
| AQS | Air Quality System national ambient air database |
| ARM | Approved Regional Methods. |
| ASTM | American Society for Testing and Materials |
| AWMA | Air and Waste Management Association |
| BACM | Best Available Control Measures. |
| BAQ | Bureau of Air Quality |
| BES | Bureau of Environmental Services |
| CAA | Clean Air Act |
| CAAA | Clean Air Act Amendments. |
| CFR | Code of Federal Regulations |
| CO | Carbon Monoxide |
| CO2 | Carbon Dioxide |
| COC | Chain of Custody |
| DAQA | Division of Air Quality Analysis |
| DAS | Data Acquisition System |
| DHEC | South Carolina Department of Health and Environmental Control |
| DQA | Data Quality Assessment |
| DQOs | Data Quality Objectives |
| EDO | Environmental Data Operation |
| EPA | United States Environmental Protection Agency |
| EQC | Environmental Quality Control (DHEC) |
| EQCSOP | EQC Environmental Investigations Standard Operating Procedures and Quality Assurance Manual |
| FEM | Federal Equivalent Method |
| FIP | Federal Implementation Plan. |
| FIPS | Federal Information Processing Standards |
| FR | Federal Register. |
| FRM | Federal Reference Method |
| GC | Gas Chromatography |
| GC/MS | Gas Chromatography / Mass Spectrometry |
| GIS | Geographical Information Systems |
| GLP | Good Laboratory Practice |
| HPLC | High Pressure Liquid Chromatography |
| IC | Ion Chromatography |
| ICP | Inductively Coupled Plasma Spectroscopy |
| LAN | Local Area Network |
| µg/M3 | Micrograms per Cubic Meter |
| MPA | Monitoring Planning Area (obsolete) |
| MQOs | Measurement Quality Objectives |
| MSA | Metropolitan Statistical Area |
| MSR | Management System Review |
| NAAQS | National Ambient Air Quality Standards |
| NAMS | National Air Monitoring Station (obsolete) |
| NCore | National Core Multipollutant Site (used after 2007) |
| NEAP | Natural Events Action Plan. |
| NEPA | National Environmental Policy Act. |
| ng/M3 | Nanograms per Cubic Meter |
| NIST | National Institute of Standards and Technology (formerly National Bureau of Standards) |
| NOx, NO, NO2 | Nitrogen Oxides, Nitrogen Oxide, Nitrogen Dioxide |
| NTTA | National Technology Transfer Advancement Act of 1995. |
| O3 | Ozone |
| OAQPS | Office of Air Quality Planning and Standards |
| OMB | Office of Management and Budget. |
| ORD | Office of Research and Development |
| PAMS | Photochemical Assessment Monitoring Stations |
| Part 50 | section of CFR containing NAAQS, FRMs and interpretation of Standards |
| Part 58 | section of CFR containing monitoring Network requirements |
| PC | Personal Computer |
| PD | Percent Difference |
| PE | Performance Evaluation |
| pH | 0 (acidic) 7 (neutral) 14 (basic) |
| PM | Particulate Matter |
| PM10 or PM10 | Particles with a nominal mean aerodynamic diameter less than or equal to 10 micrometers. |
| PM10 - 2.5 | Particles with a nominal mean aerodynamic diameter greater than 2.5 micrometers and less than or equal to 10 micrometers. |
| PM2.5 or PM2.5 | Particles with a nominal mean aerodynamic diameter less than or equal to 2.5 micrometers. |
| POC | Pollutant (parameter) Occurrence Code |
| PPB | Parts per Billion |
| PPM | Parts per Million |
| PQAO | Primary Quality Assurance Organization |
| PSD | Prevention of Significant Deterioration |
| QA | Quality Assurance |
| Qa | sampler flow rate at ambient (actual) conditions of temperature and pressure. |
| QA/QC | Quality Assurance/Quality Control |
| QAPP | Quality Assurance Project Plan |
| QMP | Quality Management Plan |
| RACM | Reasonably Available Control Measures. |
| SAFE-TEA-LU | Safe Accountable Flexible Efficient-Transportation Equity Act-A Legacy for Users. |
| SIGIS | Shared and Integrated Geographic Information System (DHEC) |
| SIP | State Implementation Plan |
| SLAMS | State and Local Air Monitoring Station primarily designed for NAAQS comparisons |
| SMP | Smoke Management Program (or Plan) |
| SO2 or SO2 | Sulfur Dioxide |
| SOP | Standard Operating Procedure |
| SPM or SPMS | Special Purpose Monitor Station not counted as part of minimum requirements |
| SQAMO | State Quality Assurance Management Officer |
| Ta | temperature, ambient or actual |
| TAR | Tribal Authority Rule. |
| TIP | Tribal Implementation Plan. |
| TSA | Technical System Audit |
| TSP | Total Suspended Particulate |
| USDA | U.S. Department of Agriculture. |
| Va | air volume, at ambient or actual conditions |
| VOC | Volatile Organic Compound |
For additional information on Exceptional Events, please contact:
Clay Lawson - (803)898-7410
S.C. DHEC
2600 Bull Street
Columbia, SC 29201
For more information please contact the Bureau of Air Quality at (803) 898-4123 or by email.