Which pollutant is emitted by both diesel engines and burning wood?

• A. Sulfur dioxide
• B. Ozone
• C. PM10
• D. Carbon dioxide

Answer: (C)

When fuels burn, they release particulates—tiny solid or liquid particles suspended in the air. PM10 refers to those particles that are 10 micrometers in diameter or smaller, which makes them easily inhalable and capable of penetrating deep into the lungs. Diesel engines produce soot and other fine aerosols, while burning wood also emits smoke rich in these fine particles. Ozone isn’t emitted directly by the engines or by burning wood; it forms later in the atmosphere from reactions involving other pollutants. The emitted gases sulfur dioxide and carbon dioxide are gases, not the small inhalable particles that characterize PM10. Because both diesel exhaust and wood combustion directly release these fine particulates, PM10 is the pollutant they have in common and are most closely associated with health impacts from combustion sources.