Aerosol Measurements Before and During Combustion of Various Pellets from Spruce Sawdust and Face Masks FFP2

. Aerosols in the atmosphere affect our health and quality of life . The most commonly measured property is their mass concentration . In this work was measured the mass concentration of aerosols by optical particle sizer in the range from 0.3 µm to 10 µm. It was realized in the laboratory with an automatic heat source for pellet combustion. A erosols were firstly measured before the combustion process, then during combustion of three types of samples: pellets from pure sawdust, pellets from 5 % of disintegrated face masks FFP2 blended with spruce sawdust and from10 % of disintegrated face masks FFP2 blended with spruce sawdust. The lowest total mass concentration was measured during the combustion of pellets from pure spruce sawdust. However, results indicate that the combustion process does not have an impact on aerosol mass concentration in the laboratory space for the particle range 0.3 - 10 µm when an automatic heat source for pellets is used.


Introduction
Aerosols are microscopic particles that float in the air, which can affect not only visibility and climate but also our health and quality of life. They represent two-phase systems, consisting of the particles and the gas in which they are suspended. Among the most important properties of aerosols is particle size, which is expressed mostly in µm. Another parameter is a shape and it is nearly always spherical for liquid aerosol particles. The most commonly measured property is just mass concentration. It is also most important for health and environmental effects [1,2].
The primary sources of aerosols in urban regions are vehicle exhausts, airports, thermal plants, industries, and combustion processes [3,4]. During winter, pollutants are closer to the surface of Earth caused of the lower height of the planetary boundary layer [5].
In the work of Pal et al. were real-time measurements realized by using Scanning Mobility Particle Sizer (SMPS) and Optical Particle Sizer (OPS). The SMPS measures aerosols in the range from 10 nm to 400 nm and the OPS measures in the range from 0.3 µm to 10 µm [6]. Individual ranges and mean diameter of particles measured by OPS are shown in Table 1. In this work was measured the mass concentration of aerosols by OPS in mentioned ranges. The measurements were realized in the laboratory with an automatic heat source for pellet combustion. Firstly, aerosols were measured before the combustion process, then they were recorded during combustion. As fuel was chosen pellets consisted of pure sawdust and the other two samples from spruce sawdust blended with disintegrated waste from face masks FFP2. Face masks FFP2 were blended with their weight proportion of 5 % and then 10 %.

Material and method
The experimental setup is shown in Figure 1. OPS device was located before the heat source. As the heat source was used automatic boiler for pellet combustion with a heat power of 18 kW and a retort burner. OPS measured the mass concentration of aerosols before combustion and then during the combustion process. During combustion were combusted firstly pellets from pure spruce sawdust, and then pellets from 5 % of disintegrated face masks FFP2 blended with spruce sawdust and 10 % of disintegrated face masks FFP2 blended with spruce sawdust. Each measurement was performed as a series of ten one-minute measurements. The resulting values of mass concentration represent average values from these series.

Conclusion
The most measured property of aerosol and important for health and environmental effects is mass concentration. In this work was mass concentration measured by OPS in laboratory space before and during the combustion process. The lowest total mass concentration was measured during the combustion of pellets from pure spruce sawdust. However, results indicate that the combustion process does not have an impact on aerosol mass concentration in the laboratory space for the particle range 0.3-10 µm when an This publication has been produced with the support of the Integrated Infrastructure Operational Program for the project: Creation of a Digital Biobank to support the systemic public research infrastructure, ITMS: 313011AFG4, co-financed by the European Regional Development Fund and VEGA No. 1/0150/22: Energy utilization of produced waste in connection with the COVID-19 pandemic through pellets as an alternative fuel and KEGA No. 021ŽU-4/2021: Primary energy conversion into heat/cold using thermodynamic cycles and compressor cycle with working substance (refrigerant) CO2.