Abstract
ABSTRACT Small aethalometers are frequently used to measure equivalent black carbon (eBC) mass concentrations in the context of personal exposure and air pollution mapping through mobile measurements (MM). The most widely used is the microAethalometer (AE51). Its performance in the laboratory and field is well documented, however, there is not sufficient data in the context of its performance in different environments. In this investigation, we present the characterization of the performance of the AE51 through field unit-to-unit intercomparisons (IC), and against a reference absorption photometer from three MM campaigns conducted in drastically different environments. Five IC parameters were considered: i) study area, ii) location of IC, iii) time of day, iv) duration of IC, and v) correction for the filter-loading effect. We can conclude that it is crucial where and how long the IC have been performed in terms of the correlation between the mobile and reference instruments. Better correlations (R2 > 0.8, slope = 0.8) are achieved for IC performed in rural, and background areas for more than 10 minutes. In locations with more homogenous atmosphere, the correction of the loading effect improved the correlation between the mobile and reference instruments. In addition, a newer microAethalometer model (MA200) was characterized in the field under extreme cold conditions and correlated against another MA200 (R2 > 0.8, slope ≈ 1.0), AE51(R2 > 0.9, slope ≈ 0.9), and a stationary Aethalometer (AE33) across all wavelengths (R2 > 0.8, slope ≈ 0.7). For MA200, the loading effect was more pronounced, especially at the lower wavelengths, hence the correction of the loading effect is essential to improve the correlation against the AE33. The MA200 and AE51 proved to be robust and dependable portable instruments for MM applications. Real-world quality assurance of these instruments should be performed through field IC against reference instruments with longer durations in areas of slowly changing eBC concentration.
Highlights
Black carbon (BC) particles are an increasingly important air pollutant in terms of human exposure to combustionrelated emission sources such as traffic and wood burning
The question remains: how does the AE51 compare against a reference absorption photometer in the context of MM performed over different environments and what factors influence their correlation?
We explore how the AE51 performed in different environments using data from three different campaigns in comparison to rack-mounted, widely used absorption photometers (MAAP 5012 and AE33), which are considered as reference instruments
Summary
Black carbon (BC) particles are an increasingly important air pollutant in terms of human exposure to combustionrelated emission sources such as traffic and wood burning. The AE51 measures the attenuation of light (880 nm) through a particle-loaded filter (T60 Teflon coated glass fiber) and converts this to an equivalent black carbon (eBC; Petzold et Copyright The Author(s). MAC can vary widely as a function of particles’ physical (i.e., coating) and chemical (composition) properties across different locations and atmospheric conditions This is a source of uncertainty for optically derived mass concentrations of eBC. Viana et al (2015) performed experiments on the unit-to-unit variability of the AE51 as well as intercomparisons (IC) against a reference instrument (multiangle absorption photometer or MAAP model 5012, Thermo, Inc., Waltham, MA USA) in a single location This investigation was not done in the context of mobile measurements (MM). The question remains: how does the AE51 compare against a reference absorption photometer in the context of MM performed over different environments and what factors influence their correlation?
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
