Analytical supplement to the article “Fires at Russian refineries: a chemical war with a delayed detonator”
Introduction
A spatial-dynamic model of an oil fire shows what falls out of the plume, where, and in what form during oil combustion; what “oil rain” actually is—and how dangerous it really is for people and the environment. In the first part, we analysed in detail the chemical composition of the smoke plume (Section 4), the cascade system of damage to the human body (Section 5), and applied the model to the real case of fires in Tuapse (Section 11). This supplement adds a spatial‑temporal axis: how toxins are distributed depending on distance, weather conditions, and geography.
Key principle. The real threat to human life and health exists in Zones 1–3 (0–300 km). Further away, concentrations drop by orders of magnitude, and we enter the realm of trace effects that require monitoring but not evacuation or the deployment of medical reserves.
Marine waters. For coastal refineries (Tuapse, Novorossiysk), a significant part of the plume can go out to sea depending on the wind direction. There is practically no inhalation exposure for people. Toxins are diluted by huge water volumes, settle in bottom sediments, are absorbed by plankton and algae, and undergo biodegradation. Photosynthetic organisms actively incorporate carbon and sulfur into their biochemical cycles. Risks for fisheries and coastal ecosystems exist, but this is not an acute toxic disaster for humans. The real threat is on land, where the plume covers settlements, farmlands, and water sources.
1. Zonal model: five types of fallout
I divide the plume into five zones. Each zone has its own set of substances, fallout mechanism, and response priority.
Zone 1 (0–10 km) – “Oil rain”
Mechanism. Mechanical carry‑over of liquid from the burning pool (boilover, annular film). Large droplets of crude oil (>50–100 μm), resins, and fuel oil fall in seconds to minutes.
Substances. Along with the droplets – killer gases: H₂S, HCN, CO, COS. Acrolein, formaldehyde, phosgene, nickel and iron carbonyls. BTEX (benzene, toluene, xylene). Acrylonitrile. Volatile organic compounds (VOC).
Threat. Maximum. Synergy of H₂S, HCN and CO blocks cellular respiration. Death occurs from immediate to 10 minutes.
Response priority. Immediate evacuation perpendicular to the wind direction for 10–15 km. No filtering mask provides protection – isolated SCBA apparatuses are required.
Zone 2 (10–90 km) – “Oil drizzle”
Mechanism. Aerosol plume. Micro‑droplets of oil and PM2.5/PM0.1 particles rise higher, then settle gravitationally.
Substances. PM with adsorbed PAHs (benzo[a]pyrene), heavy metals (vanadium, nickel, lead, mercury), dioxins, furans, PCBs, nitrosamines. In the gas phase – SO₂, NOₓ, formaldehyde, residual acrylonitrile.
Threat. Very high. PM becomes a transport system – delivers toxins into the blood, causing systemic inflammation, thrombosis, heart attacks, strokes within the next 24–72 hours.
Response priority. Deployment of cardiological and pulmonological reserves. 72‑hour monitoring of evacuees.
Zone 3 (90–300 km) – “Black rain”
Mechanism. Coagulation of soot particles and their hydrophilization by sulphates. Particles become active condensation nuclei and are washed out by rain.
Substances. Soot with adsorbed dioxins, furans, PCBs, nitrosamines, heavy metals, PAHs. Sulphate conversion (SO₂ → SO₄²⁻).
Threat. Elevated chronic threat. Dioxins, PCBs, nitrosamines, heavy metals, benzene settle in soils and food chains. This is not about guaranteed consequences, but about an increased risk (under conditions of prolonged exposure) of cancer, immunodeficiency, teratogenesis, neurodegeneration over 5–20 years.
Response priority. Medical‑biological monitoring: oncological screening after 6–12 months and annually. Monitoring of food chains (fish, milk, vegetables).
Zone 4 (300–2000 km) – “Acid rain”
Mechanism. SO₂ → SO₄²⁻ (6%/h), NOₓ → NO₃⁻ (22%/h). Photochemical ageing of aerosol.
Substances. H₂SO₄, HNO₃, sulphate and nitrate aerosols. Black carbon (BC), trace PAHs, dioxins, heavy metals at low concentrations.
Threat. Moderate ecological impact. Concentrations are significantly lower than in Zone 3. Acid rain affects soils and water bodies, but this is a background process partially compensated by the natural buffering capacity of ecosystems.
Response priority. Environmental monitoring of soils, water bodies, agricultural lands.
Zone 5 (>2000 km) – “Glacier footprint”
Mechanism. Upper tropospheric transport. Only the finest black carbon particles and trace amounts of persistent organic pollutants reach these distances.
Substances. Black carbon (BC), trace dioxins, PCBs, heavy metals (ng/m³, pg/m³).
Threat. Global climatic impact. Black carbon on glaciers reduces albedo, accelerating melting. Background increases of persistent pollutants in the Arctic biota require monitoring.
Response priority. Scientific and climate monitoring. Climate policy.
Scheme 1. Spatial‑dynamic model of oil fire fallout. Five zones, substances, mechanisms, cascade levels, and response priorities.
2. Time dynamics: zones as phases of a single process
Zones are not static rings, but states of one particle over time. The same SO₂ molecule or soot particle travels through all five phases.
| Phase | Time | Distance | State of substance | Type of fallout |
|---|---|---|---|---|
| 1. Birth | 0–1 h | 0–10 km | large droplets (>50 μm), hot gases | oil rain |
| 2. Aerosol phase | 1–6 h | 10–90 km | micro‑droplets + PM2.5 with adsorbates | oil drizzle |
| 3. Coagulation | 6–24 h | 90–300 km | soot + sulphates, hydrophilic envelope | black rain |
| 4. Chemical conversion | 24–72 h | 300–2000 km | SO₂ → H₂SO₄, NOₓ → HNO₃ | acid rain |
| 5. Residual fraction | days–weeks | >2000 km | black carbon BC, trace PAHs | glacier footprint |
Concentrations decrease with distance approximately as the inverse square of the distance. What is measured in ppm and mg/m³ in Zone 1 becomes ppb and μg/m³ in Zone 3, and ppt and ng/m³ in Zone 5.
Scheme 2. Zones are states of matter in time. Evolution of the plume from mechanical carry‑over to the residual fraction.
3. Predictive framework: how to forecast the scenario
Based on the model, we formulate six explicit rules. They allow, using the weather forecast and the characteristics of the burning facility, to predict the shift of zones and the response priorities.
| Condition (IF) | Consequence (THEN) | Action (ACTION) |
|---|---|---|
| Wind >50 km/h | zones 1–3 stretch 2‑3 times | zone 2 covers more population |
| Rain within first 12 h | black/acid rain shifts to 20–50 km | monitor soil and water closer to the epicentre |
| Temperature inversion | H₂S, HCN, CO, PM2.5 are pressed to the ground | expand the evacuation zone |
| Humidity >80% | soot hydrophilises faster | zone 3 approaches the epicentre |
| Dry, no precipitation | zones 2–4 stretch | priority – inhalation risk |
| Presence of chlorine (sea, PVC) | increased formation of dioxins, PCBs | long‑term oncology and immunity monitoring |
These rules make the model predictive. Even before the plume reaches a city, one can determine the priorities: evacuation, medical reserves, environmental monitoring, or climate policy.
Scheme 3. Explicit rules of the model: predictive framework. if → then → action – dependence on weather conditions and environmental factors.
4. Integrated pipeline: from source to consequences
All of this is a single system. No stage can be considered separately.
Fire (sulphurous oil, metals, chlorine) → Emission (SO₂, H₂S, HCN, CO, PM, PAHs, dioxins, PCBs, BTEX, acrylonitrile, phosgene, carbonyls, heavy metals) → Transport (wind, humidity, inversion, precipitation) → Transformation (SO₂→H₂SO₄, coagulation, hydrophilisation) → Fallout (zones 1–5) → Damage (cascade levels 1–4, type of disaster).
Key principle. The environment does not just transport toxins – it transforms them and determines the damage mechanism depending on distance, time, and weather conditions. Real impact is determined not only by the emission but also by the environment.
Scheme 4. Unified system of transport, transformation and damage. Integrated pipeline from source to consequences.
5. Impact intensity and hazard gradation
The impact intensity decreases sharply with distance from the source. In Zone 1 it is an acute threat to life on a time scale of minutes. In Zone 2 – high medical threat manifesting over hours and days. In Zone 3 – already an elevated long‑term risk (under conditions of prolonged exposure) that appears over years. In Zone 4 the impact becomes moderate and primarily ecological. In Zone 5 a background level of impact with a climatic scale forms.
In distant zones it is important to distinguish between actual effects and probabilities. We are not talking about guaranteed consequences, but about an increased risk of cancer, immune, and teratogenic effects in the long term. These risks materialise only under conditions of prolonged exposure and the incorporation of pollutants into food chains.
Not all toxins reach distant zones. A significant part of the substances dissipates in the atmosphere, degrades under photochemical processes, settles at shorter distances, or transforms into less active forms. Some are incorporated into biogeochemical cycles even before reaching zones 3–5. This leads to an additional reduction of real concentrations in remote regions.
The open sea does not create conditions for mass inhalation exposure. In marine environments, processes of dilution, sedimentation into bottom deposits, biodegradation, and incorporation of substances into food chains through plankton and algae dominate. This forms a different type of impact – not acute toxic, but ecological, with potential consequences for biota and fisheries, but without an immediate threat to human life in the short term.
Thus, the danger is non‑linear and decreases rapidly with distance. The main threat to human life and health is localised in zones 1–3, while in distant zones background, ecological, and long‑term processes dominate, which require monitoring but not emergency response measures.
6. Conclusions
Zone 1 (0–10 km). Maximum threat. Death from H₂S, HCN, CO within minutes. Evacuation. SCBA.
Zone 2 (10–90 km). Very high threat. Heart attacks, strokes, pulmonary oedema within a 24–72 hour window. Cardiology, pulmonology. 72‑hour monitoring.
Zone 3 (90–300 km). Elevated chronic threat. Increased risk (under prolonged exposure) of cancer, immunodeficiency, teratogenesis over 5–20 years. Medical‑biological monitoring. Monitoring of food chains.
Zone 4 (300–2000 km). Moderate ecological impact. Concentrations significantly lower. Acid rain affects soils and water bodies. Environmental monitoring.
Zone 5 (>2000 km). Trace concentrations. Main problem – climatic (soot on glaciers). Scientific and climate monitoring.
Marine waters. For coastal refineries, the plume may go out to sea. There is practically no inhalation exposure. Toxins are diluted, biodegraded, absorbed by plankton and algae. Risks for fisheries and ecosystems exist, but this is not an acute disaster for humans. The real threat is on land.
Practical summary. Response protocols must be differentiated by zone and adaptive to weather conditions. The real fight for human life and health is in zones 1–3. Beyond that – monitoring, science, policy.
References
- First part: “Fires at Russian refineries: a chemical war with a delayed detonator” (Sections 4, 5, 11).
- Hobbs P.V., Radke L.F. (1992). Airborne Studies of the Smoke from the Kuwait Oil Fires. Science 256(5059):987–991.
- Bakan S. et al. (1991). Climate response to smoke from the burning oil wells in Kuwait. Nature 351:367–371.
- Aurell J., Gullett B.K. (2010). Aerostat sampling of PCDD/PCDF emissions from the Gulf oil spill in situ burns. Environ. Sci. Technol. 44(24):9431–9437.
- CEOBS (2026). Black rain: the health and environmental risks from Tehran’s oil fires.
- Data from Rospotrebnadzor on exceedances of MPC for benzene and xylene in Tuapse (April 2026).
Author: Vladislav Balinsky, chemist, biologist, head of NGO “Green Leaf”.
Original publication (Ukrainian): Green Leaf – Eco Newspaper of Odesa