Which pollutants are typical primary emissions from coal-fired power plants?

• A. Sulfur dioxide (SO2) and nitrogen oxides (NOx)
• B. Ozone (O3) and methane (CH4)
• C. Sulfates and nitrates
• D. Ozone and sulfate

Answer: (C)

Primary emissions are substances released directly from the burning process in a coal-fired power plant. When coal is combusted, it emits pollutants like sulfur dioxide (SO2) and nitrogen oxides (NOx) straight into the exhaust. Sulfates and nitrates, by contrast, form in the atmosphere from those emissions after they’re released—SO2 and NOx react with water, oxygen, and other chemicals to become sulfate and nitrate particles. That makes them secondary pollutants, not primary. Ozone is also a secondary pollutant, created from reactions in sunlight involving NOx and volatile organic compounds. Methane is a greenhouse gas and not a typical primary emission from coal plants. So the pollutants typically emitted directly from coal-fired power plants are sulfur dioxide and nitrogen oxides.