According to the Environmental Protection Agency (EPA), which one of the following is the largest source of sulphur dioxide emissions?

(a) Locomotives using fossil fuels
(b) Ships using fossil fuels
(c) Extraction of metals from ores
(d) Power plants using fossil fuels

The correct answer is:(d) Power plants using fossil fuels

Power plants using fossil fuels are the largest source of sulfur dioxide (SO₂) emissions. According to the Environmental Protection Agency (EPA), the majority of SO₂ emissions come from the combustion of fossil fuels at power plants, accounting for 73% of total emissions .

Explanation

(a) Locomotives using fossil fuels: While locomotives do contribute to SO₂ emissions, they are not the largest source. They are considered smaller sources compared to power plants and other industrial facilities .
(b) Ships using fossil fuels: Ships are significant contributors to SO₂ emissions, especially those using high-sulfur fuels. However, they are not the largest source. Recent regulations have aimed to reduce sulfur content in marine fuels, which has decreased their contribution .
(c) Extraction of metals from ores: The extraction and processing of metals, such as smelting, do release SO₂. However, this source is smaller compared to emissions from power plants .
(d) Power plants using fossil fuels: This is the largest source of SO₂ emissions. Power plants burning coal and oil release substantial amounts of SO₂ into the atmosphere, making them the primary contributors .

Sulfur Dioxide (SO₂) Emissions:
- Definition: SO₂ is a colorless, reactive gas with a pungent odor, produced primarily from the combustion of sulfur-containing fuels like coal and oil .
- Health Effects: Short-term exposure can cause respiratory problems, including difficulty breathing, throat irritation, and aggravation of asthma. Long-term exposure can lead to respiratory illnesses and cardiovascular diseases .
- Environmental Impact: SO₂ contributes to the formation of acid rain, which can harm ecosystems, damage buildings, and reduce visibility by forming sulfate particles that cause haze .
- Regulations: Various regulations, such as the Clean Air Act in the U.S., aim to limit SO₂ emissions from power plants and other industrial sources. Technologies like scrubbers are used to remove SO₂ from emissions before they are released into the atmosphere.
- Reduction Measures: Transitioning to cleaner energy sources, such as natural gas and renewables, and implementing stricter emission controls can significantly reduce SO₂ emissions .