Which pollutant has the smallest mean emission value?

Which pollutant has the smallest mean emission value?

• A. CO2
• B. Particulate emissions (part)
• C. NOX
• D. HC

Answer: (B)

Mean emission value is the average amount a pollutant is released across all measured samples. To identify the smallest mean, consider typical emission scales and units. Particulate matter is usually reported in milligrams per kilometer, while CO2 is in grams (or kilograms) per kilometer, and NOX and hydrocarbons are in grams per kilometer. Because the mass of particulates per distance is generally much lower than the mass of CO2, NOX, or HC in most datasets, the average particulate emissions end up being the smallest. This is why particulate emissions commonly show the smallest mean value, even though they can have significant health impacts.

Mean emission value is the average amount a pollutant is released across all measured samples. To identify the smallest mean, consider typical emission scales and units. Particulate matter is usually reported in milligrams per kilometer, while CO2 is in grams (or kilograms) per kilometer, and NOX and hydrocarbons are in grams per kilometer. Because the mass of particulates per distance is generally much lower than the mass of CO2, NOX, or HC in most datasets, the average particulate emissions end up being the smallest. This is why particulate emissions commonly show the smallest mean value, even though they can have significant health impacts.