AQESHOW - Abstract

Abstract Information :

Ambient aerosol number concentration monitoring has drawn significant interest since the World Health Organization WHO gave recommendation for limits on particle number concentration (PN) for particles larger than 10 nm(WHO, ch4.3). Ambient PN is monitored in two somewhat distinct categories: high end, consisting of condensation nucleus counters; and low end, consisting of simple optical counters. The drawbacks of high-end instrumentation for monitoring are investment and maintenance costs. Furthermore, small particles tend to be more dynamic on their population statistics, thus requiring more dense monitoring network to give representative information than existing monitoring networks employed for particle mass monitoring. Low-cost instrumentation is not typically sensitive to particles smaller than the wavelength of the optical excitation system, falling far short of the recommended 10 nm cut-off size and missing the great majority of PN. These shortcomings need to be addressed to allow widespread monitoring of PN down to the WHO recommended particle sizes and concentrations. We present an ambient PN monitoring system, Pegasor Airam, based on a single channel electrical particle sensor, and comparison of results in ambient field conditions to condensation nucleus counters and other instruments.The monitor is based on a sensor developed for vehicle periodic technical inspection (PTI) use, conforming to the PN measurement requirements, such as repeatability, linearity, and detection efficiency. The difference to the PTI requirements are lower cutpoint, 10nm versus for ambient and 23nm of the emission measurement; and removal of volatile particles for PTI use. The sensor is developed from an existing sensor type, PPS-M (Rostedt et al), but with advanced features allowing greater accuracy over different particle sizes. Sensor also extracts other parameters form the signal beyond PN, such as estimated median particle diameter and lung deposited surface area (LDSA). Reference WHO global air quality guidelines. Particulate matter (PM2.5 and PM10), ozone,nitrogen dioxide, sulfur dioxide and carbon monoxide. Geneva: World Health Organization; 2021. Rostedt, Antti & Arffman, A. & Janka, Kauko & Yli-Ojanperä, Jaakko & Keskinen, Jorma. (2014). Characterization and Response Model of the PPS-M Aerosol Sensor. Aerosol Science and Technology. 48. 10.1080/02786826.2014.951023.