Kritika Shukla1,2, Shankar G. Aggarwal This email address is being protected from spambots. You need JavaScript enabled to view it.1,2

1 Gas Metrology, Environmental Sciences and Biomedical Metrology Division, CSIR-National Physical Laboratory, Dr. K.S. Krishnan Marg, New Delhi-110012, India
2 Academy of Scientific and Innovative Research (AcSIR), Ghaziabad-201002, India

Received: April 30, 2022
Revised: August 2, 2022
Accepted: August 6, 2022

 Copyright The Author(s). This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are cited.

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Shukla, K., Aggarwal, S.G. (2022). A Technical Overview on Beta-Attenuation Method for the Monitoring of Particulate Matter in Ambient Air. Aerosol Air Qual. Res.


  • Systematic review of advancement in beta attenuation technique for particulate monitoring.
  • Biases affecting the performance of beta gauge system.
  • Compilation of literature developing correction factors to improve the measurement data.
  • Identified the need for region specific calibration of each unit of instrument.
  • Modification in beta gauge system is important to generate valid air quality data.


Beta-attenuation technique is one of the widely used real-time technique for ambient particulate matter (PM) measurements since it allows continuous measurement while requiring minimal operator attention. Like any other technique, this method has several limitations that have been recorded in many studies. Beta-attenuation technique is dependent on the meteorological conditions as well as operational factors, which lead to over- or underestimation in the mass measurements in comparison to the reference method. However, the factors that affect its measurement and the variations in its performance under different conditions are not listed or reviewed in a comprehensive manner in a single document. Also, the systematic advancement of its development and implementation in ambient air measurements have not been documented in literature used by the air quality community. It is important for the user of this technique to have a detailed understanding of its principle and operation. Consequently, this article discusses the research, development, technology, and measurement of beta-attenuation method in depth. Although this review emphasizes primarily PM10 measurement results but some PM2.5 studies are also included. Our review reveals that federal equivalent method (FEM) designated beta gauge monitors in various studies performed better (with slope < 1.5 and intercept < 2 µg m-3) during high RH ambient conditions against reference or federal reference method (FRM). Studies related to PM10 showed that cut-off size, high mass loading and high ambient RH (>80%) have impact on beta gauge measurements. Therefore, it is recommended to clean inlet once a week and use smart heater to control RH at or below 35%. PM2.5 studies also confirm the effect of relative humidity on beta gauge measurements.

Keywords: Beta-attenuation technique, Gravimetric method, PM10, PM2.5, Relative humidity, Correction factor

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