Toxic sulfur dioxide plume from Tehran oil fires spreads over area

When oil storage and refining facilities in Tehran ignited in early March 2026, the resulting blaze emitted a massive sulfur‑dioxide (SO₂) plume that satellite measurements say spread across an area comparable to Italy ≈ 300,000 sq km [1]. The two‑day fire released about 29.8 kilotons of SO₂, a corrosive gas that can form acid rain and cause severe respiratory problems [2].

Key takeaways

• The fire lasted roughly two days, beginning on March 7, 2026 [3].
• Satellite analysis estimates total SO₂ emissions at 29,800 tons (2.98 × 10⁴ t) [2].
• The plume covered about 300,000 sq km (≈ 115,830 sq mi), an area the size of Italy [1].
• SO₂ concentrations rose from a regional mean of 0.8 Dobson Units to 2.0 DU during the event [3].
• Air‑quality alerts were issued in neighboring countries, including Turkmenistan and Kazakhstan, highlighting cross‑border health risks [4].

Satellite tracking reveals the scale of the emission

Chinese researchers published a paper in Advances in Atmospheric Sciences detailing how two different satellite constellations—China’s Fengyun‑3 series and Europe’s Sentinel‑5P—captured the SO₂ plume in near‑real time [3]. The analysis showed the fire’s emissions were comparable to moderate volcanic eruptions, with the plume moving northeastward and reaching East Asia after a two‑day transport [3]. Continuous tracking, the authors argue, is essential for early warning of downstream exposure, especially when ground‑based monitoring is limited [2].

Regional impacts and health concerns

The toxic plume drifted east and northeast, prompting air‑quality alerts in Turkmenistan, Kazakhstan, Uzbekistan, and Tajikistan, and raising concerns for western Afghanistan and Pakistan [4]. Experts note that SO₂ is a strong irritant and a precursor to acid rain; when mixed with water it can produce “black rain” containing oil droplets and soot, further contaminating soil and water supplies [2][3]. Residents near the Shahran depot reported immediate respiratory distress and skin irritation, underscoring the acute health threat [3].

Why it matters

The Tehran incident illustrates how modern conflicts can generate environmental hazards that transcend borders. Satellite‑based monitoring filled a critical data gap, providing quantitative estimates of emissions and plume trajectories that ground stations could not capture [3]. Researchers warn that without reliable early‑warning systems—hindered by internet blackouts and limited infrastructure—communities remain vulnerable to rapid‑moving pollution events [2]. The findings highlight the need for integrated, real‑time atmospheric monitoring to inform public‑health responses and mitigate cross‑regional impacts in future industrial or conflict‑related disasters.