**1. Introduction**

454 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

poplars, Plant Methods, 7:9, pp. 1-10

ISBN 80-213-1346-3

Pertanika 14, pp. 15-81

Univerzity of Life Sciences. Praha, ISBN 80-213-0559-2

of Analytical Chemistry, John Wiley&Sons, pp. 10815-10837

[5] Jankovský M., Lachman J., Staszková L. (1999) Wood Chemistry (in Czech). Czech

[6] Roček I. (2005) Wood of Tropical Areas (in Czech). Czech Univerzity of Life Sciences,

[7] Zhou G., Taylor G., Polle A. (2011) Ftir-atr-based prediction and modeling of lignin and energy contents reveals independent infra-specific variation of these traits in bio energy

[8] Jungnikl K., Paris O., Fratzl P., Burgert I. (2008) The implication of chemical extraction treatments on the cell wall nanostructure of soft wood, Celulose 15, pp. 407-418 [9] Lau S. (1992) FT-IR spectroscopic studies on lignin from some tropical wood and rattan,

[10] Coates J. (2000) Interpretaion of infrared spectra and practical approach. Encyclopedia

[11] Houdak J. (2011) New information about iron metabolism in human body. Available:

http://www.slideshare.net/jirihouda/metabolismus-eleza%20/ (in Czech)

Particulate matter is a natural part of the atmosphere, where the solid or liquid particles are suspended in the air. These suspended particles, also known as suspended particulate matter represents a dispersion aerosol system. In the air there are many types of microscopic airborne particles originated from both natural and anthropogenic processes, such as atmospheric clouds of water droplets, photochemically generated particles, re-suspended particulates, fumes arising from the production of energy, etc. They are present in various forms, eg. mists, fumes, dust. The atmosphere contains particles of the size ranging from slightly larger than molecules up to hundreds of micrometers, which consists of a variety of chemical compounds [1]. Depending of their lifetime, the particulates observed at a location can be both of local origin or the product of the transport over distances of hundreds to thousands kilometres.

Particulate matter is mainly classified by particle size distribution as follows [2]: Coarse Particles (CP) include all particles with an aerodynamic diameter (diameter of a sphere with unit density and mass equal to the mass of the provided particle) greater than 2.5 micrometers and less than 10 micrometers. These particles are identified as PM2.5-10. PM10 is an abbreviation used for so called "thoracic" particles with the diameter under 10 μm. Fine Particles (FP) include all particles having an aerodynamic diameter less than 2.5 micrometers and greater than 0.1 micrometers (PM2.5). Ultrafine Particles (UFP) include all particles the aerodynamic diameter of which is less than 0.1 micrometers. These size limits are not sharp; the cyclone and impactor pre-separators remove half of the particles at the cut size and larger particles with increasing efficiency.

Increase in particulate matter air contamination and its negative impact on human health have resulted in efforts to monitor and identify the pollutants. The particulate mass concentrations in a very clean urban environment are about 10 g.m-3, which correspond to

© 2012 Estokova and Stevulova, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. © 2012 Estokova and Stevulova, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

2.107 particles in 1 m3. In the polluted urban air the particle concentrations are higher than 1011 particles in 1 m3 and their mass concentrations may be higher than 100 g.m-3 [1,3]. In the Slovak Republic, the average annual outdoor PM10 concentrations ranged from 11.6 –18 g.m-3 in 2009 [4].

Investigation of Suspended and Settled Particulate Matter in Indoor Air 457

buoyancy influences the motion of contaminated air within the building. Mechanical and/or natural ventilation and infiltration define air exchange rate, and thereby the amount of outdoor particles penetrating into the building interior. The efficiency of filters integrated in mechanical ventilation systems and natural ventilation by open windows allows the estimations of particle penetration in the dependence on outdoor aerosol concentration, whereas infiltration through cracks in the building envelope is uncontrolled and depends not only on physical properties of contaminated air but mainly on particle deposition on

Operation, the number and behaviour of inhabitants, i.e. type, emission intensity and amount of indoor contamination sources determine temporal and spatial variations of indoor aerosol distribution. In addition, wet processes such as cleaning, washing, drying and ironing increase relative humidity which can lead to variations in particle size distribution [20]. Physical properties of employed building materials such as thermal conductivity influence surface-to-air temperature difference, thermal convection and thermophoresis (or thermoprecipitation). This process is significant in the winter season when constructions separate heated from unheated areas. Chemical composition of particulate matter can influence the appearance of the electrostatic charge. The total aerosol concentration is determined by the balance between source emissions and aerosol decay due

This chapter aims to present the results of the investigation of both suspended and settled particulate matter occurring indoors. The mass concentration and surface concentration measured were monitored for suspended and settled particulate matter, respectively. The chemical composition with special regard to the metals content as well as the morphology of

The aerosol particulate decay in indoor environment occurs by two mechanisms ventilation and deposition. In general, ventilation is a positive mechanism for the loss of particles from indoor air. However, in real conditions, it often may cause entering the outdoor pollutants with supplied air into the indoor environment. The extent which ventilation contributes to the reduction of the indoor concentrations depends on the way of air exchange which can be carried out by natural air change, infiltration or ventilation systems. If the ratio of indoor and outdoor concentrations I/O reaches a value more than 1, the positive venting mechanism will result in a reduction of particulate matter concentration due to dilution. Otherwise, the contamination of indoor air increases by addition of outdoor particulate matter, mainly by natural air change. Ventilation systems should ensure the particulate matter concentration in the indoor environment is not increasing due to utilization of special filters in the inlet. In addition, coarse particles in ventilation system are often deposited by gravitational process which also leads to the removing of particles from the air supplied. On the other hand, particles deposited in the pipes can be re-suspended in

to indoor air chemical processes and aerosol loss mechanisms [2].

surface cracks [18,19].

indoor particulates was studied.

**2. Indoor particulate matter decay** 

dependence on the air flow speed [21].

Danger of toxic inhalation exposure depends on both the physical and chemical characteristics of particulate matter and thus the study of its properties is essential to assess the health risks. Exposure to PM in ambient air has been linked to a number of different health outcomes, ranging from modest transient changes in the respiratory tract and impaired pulmonary function, through increased risk of symptoms requiring emergency room or hospital treatment, to increased risk of death from cardiovascular and respiratory diseases or lung cancer. The elderly, children, and people with chronic lung disease, influenza, or asthma, are especially sensitive to the effects of particulate matter [5]. Multiple studies have showed that a short-term exposure to particulate matter may associated with increased cardiovascular mortality [6-8]. The occurrence of particulate matters in the air interferes with human health not only due to its composition but also due to its specific properties. The large specific particle surface takes a share on the catalysis of heterogeneous chemical reactions and on adsorption of other pollutants and their transport [9].

Sources of particulate matter occur in the outdoor air as well as in the indoor environment. Ambient air concentrations are strongly dependent on meteorological factors in contrast to the indoor environment which is much more stable. The suspended particulate matter present in the indoor air is cumulated and as reported by [10-12] the indoor particulate concentrations are often measured to be higher than those outdoors. With the emphasis on both energy conservation and efficiency, mainly new home construction can create the problem of indoor air pollution. Vapour barriers, tight windows, weather-stripping and caulk have reduced or stopped fresh air from infiltrating and replacing stale air. Special attention must be paid to indoor air contamination because people spend a substantial portion of their time in indoor environment [13].

If indoor air pollution is investigated, both outdoor and indoor sources have to be considered, because the outdoor air is an important source of indoor particles pollution. Indoor particle concentration depends on penetration of outdoor particles into the indoor environment and on intensity of indoor aerosol sources [2]. Indoor particulate matter sources include building materials, cooking, heating and all activities related to combustion processes, smoking, cleaning and moving of inhabitants [14,15]. The importance of indoor sources depends significantly also on the number and habits of the inhabitants. It was noted [16] that the concentration of PM2.5 was 2.8 times higher in houses where people smoked.

The behaviour of indoor aerosols is affected by the structural system of a building, material characteristics, the way of air exchange, the operating mode of indoor environment in the presence of inhabitants. The structural systems of a building along with the physical properties of the outdoor air (wind direction and intensity, the difference in the density of the indoor/outdoor air, the difference in the indoor/outdoor air temperatures etc.) determine interzonal transport of pollutants [17]. In multi-floor buildings, the flow induced by buoyancy influences the motion of contaminated air within the building. Mechanical and/or natural ventilation and infiltration define air exchange rate, and thereby the amount of outdoor particles penetrating into the building interior. The efficiency of filters integrated in mechanical ventilation systems and natural ventilation by open windows allows the estimations of particle penetration in the dependence on outdoor aerosol concentration, whereas infiltration through cracks in the building envelope is uncontrolled and depends not only on physical properties of contaminated air but mainly on particle deposition on surface cracks [18,19].

Operation, the number and behaviour of inhabitants, i.e. type, emission intensity and amount of indoor contamination sources determine temporal and spatial variations of indoor aerosol distribution. In addition, wet processes such as cleaning, washing, drying and ironing increase relative humidity which can lead to variations in particle size distribution [20]. Physical properties of employed building materials such as thermal conductivity influence surface-to-air temperature difference, thermal convection and thermophoresis (or thermoprecipitation). This process is significant in the winter season when constructions separate heated from unheated areas. Chemical composition of particulate matter can influence the appearance of the electrostatic charge. The total aerosol concentration is determined by the balance between source emissions and aerosol decay due to indoor air chemical processes and aerosol loss mechanisms [2].

This chapter aims to present the results of the investigation of both suspended and settled particulate matter occurring indoors. The mass concentration and surface concentration measured were monitored for suspended and settled particulate matter, respectively. The chemical composition with special regard to the metals content as well as the morphology of indoor particulates was studied.
