Air pollutant emission factors from new and in-use motorcycles

The emissions of carbon monoxide (CO), nitrogen oxides (NOx) and total hydrocarbon (THC) from 7 new and 12 in-use motorcycles with or without the catalyst were evaluated by testing these vehicles on a dynamometer. Also the concentrations of volatile organic compounds (VOCs) in five driving patterns, including idle, acceleration, 30 km h−1 cruise, 50 km h−1 cruise, and deceleration, were monitored.Experimental results indicate that the emissions of CO and THC from in-use motorcycles are significantly higher than new ones, but not for NOx, and the emissions of THC from 2-stroke motorcycles are much higher than 4-stroke ones. The emissions of VOCs from in-use motorcycles are higher than new motorcycles for all five driving patterns, and those from 2-stroke engines are higher than 4-stroke motorcycles. Emission of VOCs in the modes of deceleration and idle accounts for the most mass emitted during the test driving cycle.