An Ambient Measurement Technique for Vehicle Emission Quantification and Concentration Source Apportionment

Area of Science:

• Environmental Science
• Atmospheric Chemistry
• Transportation Emissions

Background:

• Accurate vehicle emission data is crucial for air quality management.
• Traditional remote sensing methods have limitations in disaggregation and source apportionment.
• Ammonia (NH3) is an important air pollutant with increasing focus on its sources.

Purpose of the Study:

• To introduce and validate a novel technique, plume regression, for measuring vehicle emissions.
• To provide highly disaggregated vehicle emissions data by vehicle type.
• To conduct source apportionment of ambient concentrations for ammonia (NH3) and nitrogen oxides (NOx) by vehicle type.

Main Methods:

• Deployment of fast-response instruments at roadsides to measure vehicle exhaust plumes.
• Application of plume regression analysis to quantify emissions and source contributions.
• Comparison of plume regression results with traditional vehicle emission remote sensing.

Main Results:

• Plume regression provides highly disaggregated vehicle emissions data comparable to traditional methods.
• Gasoline passenger cars are identified as the primary source of NH3 emissions.
• Diesel vehicles demonstrate well-controlled NH3 emissions, with factors generally below 0.06 g kg-1, except for Euro VI buses.

Conclusions:

• Plume regression is a flexible and valuable technique for roadside air pollution monitoring.
• Gasoline vehicle NH3 emissions increase with mileage, highlighting a need for improved emission controls.
• Understanding vehicle-specific emissions is key to effective air quality strategies and pollution reduction.