Sampling and interpretation errors in aerosol monitoring.
The aerosol recorded by simple filter collection or by sophisticated instrument aerosol monitoring may differ considerably from the original, unsampled aerosol. Through use of particle-sizing instruments and computer modeling, the potential biases in sampling, display, and interpretation are demonstrated. The aerosol-size distribution and, therefore, the reported number or mass concentration may be affected by the characteristics of the sampling inlet, the transport to the sensor and the sensor itself. The particle count in specific size ranges determines the precision of the registered particle-size distribution, depending on the weighting chosen. The type of display, by histograms or cumulative plot, focuses on different aspects of the size distribution, and the calibration of the aerosol monitor may modify it further. Particle-size classification to simulate a specific region of the human respiratory system may be achieved through inertial classification or the sensitivity characteristics of the aerosol sensor. Aerosol monitors using passive sampling register the same aerosol-size distribution as active ones, if the aerosol is transported to the sensor with the same efficiency as in the active mode. The sources of various types of errors are presented using computer simulations of typical aerosol-size distributions, often combined with measurements found in the literature. Presentation of these errors in graphical format allows the health professional to estimate more accurately the health implications of aerosol measurements.
Willeke
K
K
Department of Environmental Health, University of Cincinnati, OH 45267-0056.
Baron
P A
PA
D000336:Aerosols / Q000032:analysis*; D000395:Air Pollutants, Occupational / Q000032:analysis*; D004391:Dust / Q000032:analysis*; D005374:Filtration / Q000295:instrumentation; D006801:Humans; D010316:Particle Size; D012815:Signal Processing, Computer-Assisted
D000336:Aerosols; D000395:Air Pollutants, Occupational; D004391:Dust