In the review proposed by Obaidullah et al. [22] the results regarding particle emission were presentedin terms of mass concentrations, number concentrations and particle size distribution. The authors alsodescribed the measurement instruments employed to quantify particles. Their results were discussed onlyfor small scale burners.Wilson et al. [23] presented discussions about collection and outdoor particle measurement.Techniques for particle measurement in small scale burners were discussed by Nussbaumer et al. [21].The authors also presented results on particulate emission factors.Giechaskiel et al. [24] analyzed the main equipment and techniques for measuring particles fromvehicular combustion.3. Instruments for Measuring Particulate MatterThere are several instruments for measuring different characteristics of particulate matter. The mostimportant measurements of particles are particle concentration and particle size.A particle size analyzer can determine the behavior of the particle in ambient air. Submicron particlescan remain in the atmosphere for a longer period of time than those of larger size.Particle concentration measurements are important to standardize emission limits, which guaranteethe standards of air quality.Particle are measured based on their classification. According to Obaidullah et al. [22], Wilson et al. [23],Wark et al. [25], and Vincent [26], the particles generated during the combustion process are classifiedas primary particles. Primary particles are directly emitted into the atmosphere. Primary particles arecomposed of fine particles, with diameter less than 2.5 μm (PM2.5), and by ultrafine particles,with diameters smaller than 0.1 μm (PM0.1) [23,26].Particles generated by mechanical or chemical reactions in the atmosphere are classified as secondaryparticles. Secondary particles are coarse. They have diameters greater than 2.5 μm. Coarse particles includeparticulate matter smaller than 10 μm in diameter (PM10) and total Suspended Particle Matter (TSP),as stated by Turner [27]. According to Wilson et al. [23], a secondary particle can contain particles frommany sources; this occurs because they can be formed by the accumulation of several other particles.Instruments that measure particle size distribution use the behavior of particles (diffusion,aerodynamics, and optical and electrical mobility), as described by Kulkarni et al. [28].In this review study, special attention will be given to equipment used for measuring particleconcentration and particle size. However, particle characterization involves study of particle morphologyas well as chemical characterization.In Figure 1, the most common particle measuring instruments were classified as concentrationmethods and size distribution methods.3.1. Concentration Measurement MethodsIn concentration methods, the PM concentration can be in mass (m), number (N) and surface area (S).These instruments are based in different measuring principles, and can be gravimetric, optical,microbalance, and electrical charge.