3.2.5. Centrifugal Measurement of Particle MassCentrifugal measurement of particle mass can be done by using a Centrifugal Particle Mass Analyzer(CPMA) or an Aerosol Particle Mass (APM).According to Giechaskiel et al. [24], the CPMA is composed of two coaxial cylindrical electrodes,one internal and another external. The internal electrode turns a little faster than the external electrode.While passing by the electrodes, the loaded particles experience electrostatic and centrifugal forces, thatact in opposed directions. Depending on the rotation speed and tension, between the electrodes, particlescan penetrate the CPMA. Johnson et al. [45] described that the CPMA classifies an aerosol by themass-to-charge ratio. According to these authors, the CPMA that measures mass-mobility is usedupstream of a DMS (Differential Mobility Spectrometer), which measures the mobility size distributionof the mass-classified particles in real-time.The main difference between the CPMA and APM is that in the APM both electrodes turn in the sameangular speed, as affirmed by Giechaskiel et al. [24].For Giechaskiel et al. [24], the advantage of these instruments is their ability to register particle masswithout the need to collect particles for weighing.3.2.6. Differential Mobility Spectrometers (DMS)Among the spectrometers based on particle mobility, the most known are the Differential MobilitySpectrometers (DMS) and the Fast Mobility Particle Sizer (FMPS), mentioned by Hosseini et al. [16]and Hossain et al. [44].However, other similar spectrometers also measure the particle mobility diameter: Scanning MobilityParticle Sizer (SMPS) and Twin Differential Mobility Particle Sizer (TDMPS).These spectrometers are composed of a particle loader, a classification column and a series ofdetectors, as described by Giechaskiel et al. [24].Giechaskiel et al. [24] emphasized that the SMPS is the most precise instrument for high resolutionsize distributions of aerosols from vehicle exhaust. Nussbaumer et al. [21] also mentioned the use ofSMPS to measure concentration in number and size distribution of particles from biomass combustion.According to these authors, there are many versions of this instrument, working in a size range from fewnanometers to 1 μm.As stated by Hosseini et al. [16], FMPS is made of two concentric cylinders (classification columns),a diffusion loader, and 32 electrometers, that cover the particle size range from five to 560 nm.The current containing positively charged particles flow along the sheath. High voltage between the twocylinders transports the particles from the point they are introduced to the other side that houses theelectrometers. Next to the column top, the particles with greater electrical mobility are collected, and theparticles with inferior electrical mobility are collected downstream.FMPS uses an electrical mobility measurement technique similar to that used in SMPS. However,instead of a CPC, the FMPS spectrometer uses multiple, low-noise electrometers for particle detection.This produces particle-size-distribution measurements with one-second resolution, providing the abilityto visualize particle events and changes in particle size distribution in real time.