Performance Evaluation of High-, Mid-, and Low-cost Analyzers to Measure Transient Emission Sources

Quantifying pollutant emissions from in-use mobile sources is a necessary part of verifying emission inventories. While source characterization using research-grade analyzers that are accurate, precise, and fast-responding is best practice, they are also expensive, bulky, and power hungry. Lower-cost sensors that are portable and battery powered are more practical in many field environments, but their suitability for exhaust plume capture measurements has yet to be proven. This study set out to evaluate the performance of low-, mid-, and high-cost black carbon (BC) and carbon dioxide (CO₂), analyzers for exhaust plume capture measurements in the quantification of BC emission rates from in-use heavy-duty diesel trucks and commercial harbor craft.

In this work, BC analyzers included Magee Scientific aethalometers AE16 and AE33, AethLabs microAeths MA300 and AE51, and UC Berkeley Aerosol Black Carbon Detector (ABCD), and CO₂ analyzers included Licor LI-7000 and LI-820, PP Systems SBA-5, and Vaisala GMP-343. These analyzers were used in the field aboard harbor craft and at the truck entrance to a major container port facility, as well as tested in the laboratory. Laboratory tests were intended to characterize analyzer performance as a function of peak concentration and duration while mimicking the concentrations of CO₂ and BC measured in the field, including concentrations beyond manufacturer specified limits. Though lower cost CO₂ analyzers performed well when calibrated with steady concentrations, their performance deteriorated when sampling rapidly changing concentrations that are typically encountered when sampling mobile sources. In-lab testing also revealed that the lower cost BC instruments failed to accurately capture peak area and had higher signal to noise ratios and therefore, less precision than compared to higher cost BC analyzers.