Environmental Forensic Investigation of Petrochemical Fire Emissions, Atmospheric Dispersion Modeling, Exposure Assessment, and Human Health Risk Evaluation
Project Overview
Large petrochemical manufacturing facilities process and store substantial quantities of highly flammable hydrocarbons under elevated temperatures and pressures. Although extensive engineering controls are designed to minimize operational risk, equipment failures can result in catastrophic releases capable of producing vapor cloud explosions, prolonged industrial fires, and widespread atmospheric emissions. These incidents present complex environmental challenges requiring multidisciplinary forensic investigations to reconstruct release mechanisms, quantify emissions, evaluate atmospheric transport, assess community exposure, and characterize potential human health impacts. Such investigations integrate environmental chemistry, air quality modeling, meteorology, toxicology, engineering analysis, regulatory data, and environmental monitoring to objectively evaluate both the magnitude and distribution of contaminant releases.
This environmental forensic investigation evaluated the environmental consequences of a major petrochemical facility fire involving the accidental release of a highly flammable petrochemical feedstock that rapidly vaporized, formed a combustible vapor cloud, and subsequently ignited. The initial explosion was followed by additional explosions and an extended fire that continued for several weeks as damaged process equipment released combustible materials. The event prompted large-scale emergency response actions, evacuation and shelter-in-place orders, extensive ambient air monitoring, and ongoing regulatory investigations. The technical evaluation reconstructed the sequence of events using engineering records, emissions inventories, emergency response documentation, meteorological observations, environmental monitoring data, and published scientific literature.
A principal objective of the investigation was to determine how airborne contaminants generated during the release and subsequent fire dispersed through nearby communities and whether atmospheric concentrations were consistent with measured monitoring data and accepted dispersion modeling techniques. Investigators reconstructed multiple emission scenarios representing the initial accidental release, sustained combustion, and changing release rates throughout the duration of the incident. Air dispersion modeling, meteorological analyses, and regulatory monitoring data were evaluated together to estimate downwind concentrations of hazardous air pollutants and identify periods when surrounding areas were most likely to experience elevated airborne exposures. This integrated approach strengthened source attribution by comparing modeled concentrations with independent field measurements collected during emergency response activities.
The investigation also evaluated the toxicological significance of chemicals released during the event, including the primary process chemical together with combustion-related pollutants such as volatile organic compounds (VOCs), benzene, particulate matter, carbon monoxide, nitrogen oxides, sulfur-containing gases, and soot. Published toxicological studies, occupational exposure literature, regulatory health benchmarks, and environmental monitoring results were integrated into a human health exposure assessment to evaluate both acute and potential longer-term exposure pathways. By combining environmental chemistry, atmospheric science, engineering analysis, exposure assessment, and toxicology, the investigation developed a scientifically rigorous framework for evaluating the environmental and public health consequences of large industrial fire events while supporting environmental consulting, regulatory investigations, environmental litigation, and expert witness testimony.
Chemicals of Concern
The primary chemical evaluated during this environmental forensic investigation was 1,3-butadiene, a highly flammable petrochemical intermediate widely used in the manufacture of synthetic rubber, plastics, and industrial resins. Under normal operating conditions, 1,3-butadiene is handled within closed industrial systems; however, accidental releases can rapidly vaporize, forming dense, flammable vapor clouds capable of ignition if an ignition source is present. In addition to its physical hazards, 1,3-butadiene is classified as a known human carcinogen following inhalation exposure and has been associated with increased risks of hematological cancers, respiratory effects, and other adverse health outcomes following prolonged or elevated exposure. The investigation therefore focused on reconstructing historical airborne releases of 1,3-butadiene and evaluating its atmospheric transport and potential community exposure.
The investigation also evaluated benzene, a volatile aromatic hydrocarbon generated both as a process chemical and through combustion of petroleum products. Benzene is recognized as a human carcinogen and is routinely monitored following petrochemical fires because inhalation represents the principal exposure pathway for nearby communities. Regulatory air monitoring conducted during the emergency response identified benzene as one of the key compounds measured throughout the incident, making it an important indicator for evaluating airborne exposure and comparing measured concentrations with modeled emissions and health-based screening values.
Additional contaminants of concern included particulate matter (PM₂.₅ and PM₁₀), carbon monoxide (CO), nitrogen oxides (NOₓ), hydrogen sulfide (H₂S), soot, and other volatile organic compounds (VOCs) generated during prolonged combustion of petrochemical materials. Fine particulate matter can penetrate deeply into the respiratory tract, while combustion gases such as carbon monoxide and nitrogen oxides are associated with respiratory and cardiovascular effects. Because these pollutants are commonly produced during large industrial fires, they were evaluated alongside 1,3-butadiene and benzene to characterize the overall composition of the airborne emission plume and to assess potential short-term community exposure.
The investigation further considered the environmental behavior of these contaminants following release. Volatile compounds such as 1,3-butadiene and benzene disperse rapidly through the atmosphere, making meteorological conditions—including wind direction, wind speed, and atmospheric stability—critical factors controlling exposure. In contrast, combustion-derived particulate matter can remain suspended in the atmosphere before depositing onto surrounding surfaces, creating both inhalation and secondary deposition pathways. These differing physical and chemical properties required separate evaluation during emissions reconstruction and atmospheric dispersion modeling.
Because large petrochemical fire events release complex mixtures rather than individual chemicals, investigators evaluated the interaction of volatile hydrocarbons, combustion products, meteorological conditions, and exposure pathways as components of a unified environmental system. Integrating environmental chemistry with toxicology, atmospheric science, and air quality monitoring provided a scientifically defensible basis for source attribution, exposure assessment, environmental consulting, regulatory investigations, and expert witness evaluations involving large industrial chemical releases.
Methods
This environmental forensic investigation employed a multidisciplinary methodology integrating historical incident reconstruction, engineering analysis, emissions estimation, atmospheric dispersion modeling, meteorological evaluation, regulatory air monitoring review, toxicological assessment, and human health exposure evaluation. Because the release involved both an acute accidental discharge and an extended combustion event lasting several weeks, investigators reconstructed multiple emission scenarios to characterize changing release conditions over time. Engineering records, regulatory reports, emergency response documentation, ambient air monitoring data, and peer-reviewed scientific literature were synthesized into a comprehensive environmental forensic assessment capable of evaluating both the magnitude of emissions and the potential for off-site exposure.
The investigation began with a review of incident records describing the sequence of equipment failures, chemical releases, explosions, emergency response activities, and subsequent fire suppression efforts. Historical timelines, engineering information, regulatory emissions reports, and publicly available investigation documents were evaluated to reconstruct the duration of the release and identify distinct operational phases, including the initial accidental release, sustained combustion, and prolonged emissions from damaged process equipment. This reconstruction established the foundation for estimating emissions and evaluating community exposure throughout the incident.
Emissions were reconstructed using reported release quantities, facility emissions inventories, and engineering calculations to develop multiple source-term scenarios representing different phases of the event. Investigators evaluated an initial rapid release together with several longer-duration emission scenarios reflecting changing release rates during the extended fire. These reconstructed emission rates were used to estimate airborne contaminant concentrations under a range of realistic operating conditions rather than relying on a single average release assumption.
Atmospheric transport was evaluated using the ALOHA (Areal Locations of Hazardous Atmospheres) model to estimate short-term hazardous vapor dispersion following the initial release. Multiple modeling scenarios incorporated different emission rates, release durations, and meteorological conditions to evaluate potential downwind concentrations. In addition, hourly meteorological observations—including wind direction, wind speed, and atmospheric conditions—were reviewed to identify periods when nearby residential areas were positioned downwind of the emission plume. These analyses were compared with ambient air monitoring data collected by regulatory agencies to evaluate consistency between modeled and measured concentrations.
Ambient air monitoring data collected during the emergency response were reviewed to evaluate measured concentrations of 1,3-butadiene, benzene, and other combustion-related pollutants. Monitoring information from fixed stations, portable instruments, and aerial surveillance was compared with modeled emission scenarios to assess the spatial and temporal distribution of airborne contaminants. Published toxicological studies and regulatory health benchmarks were then incorporated into an exposure assessment to evaluate potential short-term inhalation hazards associated with the incident.
Finally, engineering analyses, emissions reconstruction, atmospheric dispersion modeling, meteorological evaluation, environmental monitoring, and toxicological assessment were integrated into a unified environmental forensic investigation. By combining historical incident reconstruction with quantitative air modeling and independent monitoring data, investigators developed a scientifically defensible framework for evaluating source attribution, airborne contaminant transport, community exposure, environmental consulting, regulatory investigations, and expert witness testimony involving major petrochemical fires and industrial chemical releases.
Results
The environmental forensic investigation demonstrated that the accidental release of a large quantity of 1,3-butadiene initiated a complex sequence of environmental events involving rapid vaporization, vapor cloud formation, multiple explosions, and an extended industrial fire that continued for several weeks. Engineering records indicated that the initial release was followed by continued emissions from damaged process equipment, resulting in both acute and sustained airborne contaminant releases. Rather than representing a single short-duration event, the investigation found that changing emission rates throughout the incident required evaluation using multiple source-term scenarios to accurately characterize potential community exposure.
Regulatory emissions inventories and engineering calculations demonstrated that 1,3-butadiene represented one of the largest reported airborne releases associated with the incident. Source-term reconstruction showed that emissions varied substantially over time, with the highest release rates occurring immediately following the initial equipment failure and lower, sustained releases continuing during the prolonged fire. Developing multiple emissions scenarios better represented the dynamic nature of the event than relying on a single average emission rate and provided a more realistic basis for subsequent atmospheric dispersion modeling.
Atmospheric dispersion modeling indicated that the highest predicted airborne concentrations occurred during the initial release, when rapid vaporization produced a dense vapor cloud capable of traveling significant distances under favorable meteorological conditions. Additional modeling scenarios representing prolonged combustion demonstrated that lower but sustained emissions had the potential to affect surrounding areas over an extended period. Comparison of modeled dispersion patterns with regulatory air monitoring data demonstrated general agreement between predicted and measured concentrations of key contaminants, supporting the use of atmospheric modeling as a scientifically defensible tool for reconstructing historical exposure conditions following large industrial chemical releases.
Meteorological evaluation further demonstrated that wind direction and atmospheric conditions were among the most important factors influencing community exposure. Review of hourly meteorological observations showed that changing wind patterns periodically transported smoke and airborne contaminants toward different surrounding areas throughout the incident. Because wind direction shifted repeatedly over the duration of the fire, potential exposure varied considerably over time rather than remaining confined to a single geographic area. Integrating meteorological observations with dispersion modeling substantially improved reconstruction of historical plume movement and strengthened interpretation of environmental monitoring results.
Ambient air monitoring conducted during emergency response activities detected 1,3-butadiene, benzene, and other combustion-related pollutants at varying concentrations throughout the response period. Fixed monitoring stations, portable field instruments, and aerial surveillance collectively provided independent measurements that complemented engineering analyses and dispersion modeling. Together, these datasets demonstrated the value of integrating measured environmental data with modeled concentrations when evaluating community exposure following industrial fires. Published toxicological literature reviewed during the investigation further supported evaluation of inhalation hazards associated with short-term exposure to these contaminants.
Overall, the investigation demonstrated that integrating historical incident reconstruction, emissions estimation, atmospheric dispersion modeling, meteorological analysis, environmental monitoring, and toxicological evaluation provides a scientifically rigorous framework for evaluating large petrochemical fire events. By combining multiple independent lines of evidence rather than relying on a single analytical method, investigators developed an objective assessment of airborne contaminant transport and potential community exposure suitable for environmental consulting, regulatory investigations, emergency response evaluation, environmental litigation, and expert witness testimony involving major industrial chemical releases.
Conclusions
This environmental forensic investigation demonstrates that evaluating the environmental and public health impacts of major petrochemical fires requires an integrated scientific approach combining engineering analysis, emissions reconstruction, atmospheric dispersion modeling, environmental monitoring, meteorology, toxicology, and exposure assessment. Because industrial chemical releases often evolve rapidly and involve changing emission rates over time, accurate reconstruction of historical exposures requires more than environmental sampling alone. Integrating modeled emissions with independent monitoring data and documented operational history provides a more comprehensive and scientifically defensible understanding of contaminant transport and potential human exposure.
The investigation also demonstrated the importance of reconstructing time-dependent emission scenarios rather than relying upon a single release estimate. The initial accidental release, subsequent explosions, and prolonged combustion each produced distinct emission characteristics that influenced contaminant concentrations and plume behavior. Incorporating these changing conditions into atmospheric dispersion modeling improved estimates of airborne contaminant transport and strengthened comparisons between modeled results and measured environmental data. This approach reduced uncertainty while providing a more realistic representation of community exposure during the incident.
Another important finding was the critical role of meteorological conditions in determining exposure patterns following large industrial chemical releases. Wind direction, atmospheric stability, and changing weather conditions significantly influenced the movement and dilution of airborne contaminants throughout the response period. Integrating hourly meteorological observations with air dispersion modeling and regulatory monitoring data allowed investigators to reconstruct plume movement with greater confidence and identify periods when nearby communities were most likely to experience elevated airborne concentrations. This integration of atmospheric science and environmental monitoring represents a key component of modern environmental forensic investigations involving accidental air releases.
Finally, this investigation illustrates how environmental forensic science supports emergency response evaluations, regulatory investigations, environmental litigation, and human health risk assessments following major industrial incidents. By combining environmental chemistry, engineering analysis, emissions estimation, atmospheric modeling, toxicology, and independent environmental monitoring, investigators developed a technically rigorous framework for evaluating source attribution and potential community exposure while maintaining an objective, evidence-based scientific approach. As industrial facilities continue to handle large quantities of hazardous chemicals, multidisciplinary environmental forensic investigations will remain essential for understanding accidental releases, improving emergency preparedness, informing remediation decisions, and supporting scientifically sound environmental decision-making.
This investigation was conducted under the direction of Dr. Paul Rosenfeld, an environmental scientist and environmental forensic expert with extensive experience in environmental exposure assessment, toxicology, air quality, environmental fate and transport, risk assessment, and environmental forensics. Through RoseyFields LLC, Dr. Rosenfeld provides scientific consulting, environmental forensic analysis, regulatory support, and expert witness services involving environmental contamination, human exposure, and public health. His technical oversight helped ensure that the methodologies, scientific interpretations, and conclusions presented in this case study are consistent with accepted scientific principles and current best practices.