Sulfur dioxide(SO2) is the most common sulfur oxide. It is a colorless gas with a strong pungent odor.
1. Natural Sources
Volcanic Activity: Sulfur dioxide accounts for a significant proportion of gases released by volcanic eruptions, with a single large-scale eruption releasing tens of thousands of tons.
Forest Fires and Biodecomposition: Natural combustion processes (such as forest fires and the decomposition of organic matter in swamps) release small amounts of sulfur dioxide.
Geothermal Activity: Geothermal steam and hot springs also emit trace amounts of sulfur dioxide, but the proportion is extremely small.
2. Anthropogenic Sources (Main Sources)
Fossil Fuel Combustion
Coal Combustion: Thermal power plants and industrial boilers burn sulfur-containing coal (sulfur content 0.5% to 3%), contributing approximately 70% of emissions.
Oil and Natural Gas: Emissions from oil refining, chemical production, and diesel vehicle exhaust (particularly high-sulfur heavy fuel oil).
Industrial Processes
Metallurgy: Released during the smelting of sulfur-containing ores (such as copper, lead, and zinc) by steel and non-ferrous metals.
Chemical Production: Direct emissions from processes such as sulfuric acid production and phosphate fertilizer production.
Other Human Activities: High-temperature industrial processes such as waste incineration and cement production also produce sulfur dioxide.
Transportation: Diesel vehicle exhaust and ship fuel combustion. Although modern vehicles use low-sulfur diesel, emissions still occur.
Statistics from 2025 show that fossil fuel combustion accounts for 70% of atmospheric sulfur dioxide pollution, with coal combustion being the dominant source.Emissions from industrial processes account for approximately 21%, while transportation and other sources combined account for less than 10%.
3.Human Health Hazards of Sulfur Dioxide (SO₂)
(1). Low Concentrations (0.3-1 ppm)
Most people can detect a pungent odor, which may cause a mild cough and throat irritation, but generally does not cause acute poisoning.
(2). Medium Concentrations (5-10 ppm)
Significant respiratory irritation symptoms may occur, such as increased coughing, difficulty breathing, chest pain, and possibly conjunctival congestion and tearing.
(3). High Concentrations (10-50 ppm)
Short-term exposure can cause acute poisoning, manifested by severe coughing, bronchospasm, pulmonary edema, and even respiratory failure.
(4). Extremely High Concentrations (50 ppm and above)
Can cause suffocation and coma, and in severe cases, can be life-threatening within minutes.
4. Protection Recommendations
(1).Avoid prolonged stays in high-risk environments, such as industrial areas and volcanically active areas.
(2).Improve indoor ventilation and avoid prolonged exposure to industrial environments containing sulfur dioxide.
(3).Wear a respirator (meeting SO₂ protection standards) when exposed to high concentrations of sulfur dioxide.
(4).Install an online sulfur dioxide gas detector monitoring system to ensure that emission concentrations meet national standards.