Which energy source produces the most air pollutants during electricity generation?

• A. Coal
• B. Fuel oil
• C. Hydroelectric
• D. Natural gas

Answer: (B)

Burning for electricity generation releases pollutants from the fuel's combustion, and the amount varies by fuel type. Coal contains more sulfur and other impurities, so burning it emits large quantities of sulfur dioxide, nitrogen oxides, and fine particulates, plus trace metals like mercury. These pollutants contribute to smog, acid rain, respiratory issues, and environmental harm. Fuel oil also releases these pollutants, but not to the same extent as coal. Hydroelectric power involves little to no combustion, so its operation emits very few air pollutants. Natural gas burns cleaner than coal and oil, with lower emissions of sulfur compounds, nitrogen oxides, and particulates, though it still releases carbon dioxide. Therefore, coal generally produces the most air pollutants during electricity generation.