Which of the following is NOT listed as a coal combustion air pollutant?

• A. Toxic Heavy Metals
• B. Water Vapor
• C. Carbon Dioxide
• D. Sulfur Dioxide

Answer: (B)

Water vapor differs from the other substances because it’s a natural part of air and combustion exhaust, not a contaminant people try to control as a pollutant. Pollutants are substances that harm health or the environment at typical exposure levels. Toxic heavy metals released by burning coal can have toxic effects and accumulate in ecosystems. Sulfur dioxide forms from sulfur impurities in coal and is a major pollutant linked to acid rain and respiratory issues. Carbon dioxide is the main greenhouse gas emitted from burning fossil fuels and is treated as a pollutant in discussions of climate impact, though its regulatory treatment is different from traditional air pollutants. Since water vapor isn’t treated as a pollutant in this context, it’s the correct choice.