Volume 14, No. 1, February 2014, Pages 1-9 PDF(486 KB)
Validation of MicroAeth® as a Black Carbon Monitor for Fixed-Site Measurement and Optimization for Personal Exposure Characterization
Jing Cai1,2, Beizhan Yan1, James Ross1, Danian Zhang2, Patrick L. Kinney3, Matthew S. Perzanowski3, KyungHwa Jung4, Rachel Miller3,4.5, Steven N. Chillrud1
1 Lamont-Doherty Earth Observatory of Columbia University, New York, NY, USA
2 School of Resource and Environmental Engineering, East China University of Science and Technology, Shanghai, China
3 Department of Environmental Health Sciences, Mailman School of Public Health at Columbia University, New York, NY, USA
4 Division of Pulmonary, Allergy and Critical Care, Columbia University College of Physicians and Surgeons, New York, NY, USA
5 Division of Pediatric Allergy and Immunology, Columbia University College of Physicians and Surgeons, New York, NY, USA
This paper reports on validation experiments with the recently developed microAeth®, a pocket-sized device which is able to obtain real-time and personal measurements of black carbon (BC) aerosol. High reproducibility was observed when comparing the results from six new individual units during fixed-site monitoring out of a window (relative standard deviation [RSD] = 8% ± 5%, N = 1442). The results obtained from the microAeth devices agreed with those obtained from a full size rack mounted Aethalometer, based on both the 1-minute data (R = 0.92, slope = 1.01 ± 0.01, N = 1380) and 24-h average data. The 24-h average of real time data obtained from the microAeths was comparable to the BC concentration obtained from 24-h integrated PM2.5 filter deposits, as determined by multi-wavelength optical absorption (R = 0.98, slope = 0.92 ± 0.07, N = 12). Rapid environmental changes in relative humidity (RH) and temperature (T) can result in false positive and negative peaks in the real time BC concentrations, though averages > 1–2-hour are only minimally affected. An inlet with a diffusion drier based on Nafion® tubing was developed in order to use BC data with a high time resolution. The data shows that the diffusion drier greatly reduce the impacts from rapid changes in RH and T when the monitoring system is worn in close proximity to the body (e.g., in the vest pocket).
Black carbon; MicroAeth; Personal exposure; Fixed-site monitoring; Humidity.