**3.3. Aerosol and dust particles generated during processing of selected exotic woods**

The objective of the measurements was to measure quantities and distribution of aerosol micro and nanoparticles generated by individual technological steps during processing of various types of tropic woods used on the market in the Czech Republic. At the same time, we also focused on the microstructure of the wood dust in the deposits and difference in the

chemical composition of the individual woods; this may play a negative role after they get into the respiratory system or into contact with skin or eye mucosa. We focused on tropical woods due their wide variety and the dramatic increase of their import to the processing market in the Czech Republic.

Experiences with Anthropogenic Aerosol Spread in the Environment 433

Note about the toxicity [6]

Sawdust and grinding dust contain lapachol – as the dyestuff, it is irritating, may damage mucosa and cause dermal problems

Risk of mucosa and skin

Sawdust may be irritant, wood dust may irritate mucosa and skin

Chemical reaction with

Poor resistance against fungi and insects

Wood dust irritates skin, contains oily resins, resists decay

Resistant against termites, the bark contains alkaloid

damage

iron

This has caused problems with identification of the technological process that generates the highest quantity of micro and nano aerosols. Despite those difficulties, we have identified the operation of the belt grinding machine as the main source of pollution in the production hall. The next experiment was conducted during the night, only with the technological operation of wood surface grinding with a grinding belt (belt grinding machine HOUFEK,

Tested woods: Ipé, Jatoba, Massaranduba, Merbau, Bangkirai, Faveira, Garapa, Teak, Bilinga.

The basic information on the tested tropic woods and on their processability and toxicity

Occurrence Note about the wood

processing [6]

Sawing – highperformance machinery is needed

Sawing – highperformance machinery is needed

Easy sawing, processing without difficulties

blunt

performance machinery

dulls the tools, difficult processing – special tools are needed

Sawing not completely easy, makes the tools

Sawing requires high-

Difficult processing Not detected

Not detected Allergenic and toxic

Planing is difficult, high-performance machinery is needed, very strong material, highly durable

PBH 300 B BASSEL, belt speed 17 m/s, grinding belt roughness AA 80, AA 100).

The temperature and humidity in the production hall: 24-25oC, 55%.

America

America

America (Brazil, Columbia)

Southeast Asia (Indonesia, Malaysia)

(Malaysia, Indonesia)

(Brazil)

Laos)

The layout of the measuring technology is shown in Figure 20.

America (Brazil, Columbia)

Southeast Asia (Indonesia, Burma,

West Africa (Sierra Leone, Nigeria, Cameroon)

reported in literature is provided in Table 5.

Ipé *Tabebuia spp.* Central and South

Jatoba *Hymenaea spp.* Central and South

Massaranduba *Manilkara spp.* South and tropical

Faveira *Porkia spp.* Tropical South

Garapa\* *Apuleia Leiocarpa* South America

*Grandis*

*Vaucle and Diderrichii*

**Table 5.** Basic data about the tested woods

*Shorea argentea* Southeast Asia

Merbau *Intsia bakerie* 

Teak *Tectona* 

Bilinga (Opepe)

Balau, Yellow (Bangkirai)

*Prain* 

Latin name of wood species

Trade name of wood species

Wood processing generates wood dust which may, depending on the size of the particles, form an aerosol or settle directly. The wood dust contains chemical substances that form the wood (polysaccharides, such as cellulose and hemicellulose, aromatic substances, such as lignin and tannins, resin terpenes, lipids, nitrogenous substances, inorganic substances etc.) depending on the wood condition, while it is impossible to exclude the presence of biological organisms, fungi, mildews or bacteria [5].

A negative effect of the wood dust on the human organism may occur in case of contact with skin or eye mucosa or inhalation by the respiratory tract. There is a general rule that the with decreasing size of the particles their respirability increases as well as their ability to bind with other substances (by sorption or condensation). Dusts from biologically highly aggressive woods may cause dermatitis, respiratory diseases, allergic respiratory problems (asthma) and carcinogenic effects (adenocarcinoma of nasal cavity and paranasal cavity). The chemical composition of wood opens a number of possibilities in contact with the biological system [6].

The measurements were conducted in the course of full operation in a production hall (area 700 m2, volume 3 500 m3) equipped with a state-of-the art filter and extraction system made by Cipres Filtr with the power output 37 kW, with a box filter CARM situated outside the hall. Despite this after a time the overall concentration of nanoparticles in the production hall increased to 4–5 x 105 N/cm3. The difference from the initial level before the shift beginning is shown in the diagram in Figure 19.

**Figure 19.** Comparison of the distribution of aerosol particles in the production hall during the operation and before the beginning of the operation

This has caused problems with identification of the technological process that generates the highest quantity of micro and nano aerosols. Despite those difficulties, we have identified the operation of the belt grinding machine as the main source of pollution in the production hall. The next experiment was conducted during the night, only with the technological operation of wood surface grinding with a grinding belt (belt grinding machine HOUFEK, PBH 300 B BASSEL, belt speed 17 m/s, grinding belt roughness AA 80, AA 100).

The temperature and humidity in the production hall: 24-25oC, 55%.

432 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

biological organisms, fungi, mildews or bacteria [5].

beginning is shown in the diagram in Figure 19.

operation and before the beginning of the operation

market in the Czech Republic.

biological system [6].

chemical composition of the individual woods; this may play a negative role after they get into the respiratory system or into contact with skin or eye mucosa. We focused on tropical woods due their wide variety and the dramatic increase of their import to the processing

Wood processing generates wood dust which may, depending on the size of the particles, form an aerosol or settle directly. The wood dust contains chemical substances that form the wood (polysaccharides, such as cellulose and hemicellulose, aromatic substances, such as lignin and tannins, resin terpenes, lipids, nitrogenous substances, inorganic substances etc.) depending on the wood condition, while it is impossible to exclude the presence of

A negative effect of the wood dust on the human organism may occur in case of contact with skin or eye mucosa or inhalation by the respiratory tract. There is a general rule that the with decreasing size of the particles their respirability increases as well as their ability to bind with other substances (by sorption or condensation). Dusts from biologically highly aggressive woods may cause dermatitis, respiratory diseases, allergic respiratory problems (asthma) and carcinogenic effects (adenocarcinoma of nasal cavity and paranasal cavity). The chemical composition of wood opens a number of possibilities in contact with the

The measurements were conducted in the course of full operation in a production hall (area 700 m2, volume 3 500 m3) equipped with a state-of-the art filter and extraction system made by Cipres Filtr with the power output 37 kW, with a box filter CARM situated outside the hall. Despite this after a time the overall concentration of nanoparticles in the production hall increased to 4–5 x 105 N/cm3. The difference from the initial level before the shift

**Figure 19.** Comparison of the distribution of aerosol particles in the production hall during the

Tested woods: Ipé, Jatoba, Massaranduba, Merbau, Bangkirai, Faveira, Garapa, Teak, Bilinga.

The basic information on the tested tropic woods and on their processability and toxicity reported in literature is provided in Table 5.


**Table 5.** Basic data about the tested woods

The layout of the measuring technology is shown in Figure 20.

Experiences with Anthropogenic Aerosol Spread in the Environment 435

Ground-off quantity

per cm2 (g)

Ground area (cm2) Ground-off

Massaranduba 371 246 0.66 Ipé 371 261 0.70 Garapa 371 308 0.83 Teak 331 266 0.80 Bilinga 466 182 0.39 Jatoba 371 167 0.45 Faveira 371 157 0.42 Bangkirai 308 195 0.63 Merbau 371 78 0.21

*3.4.2. Distribution of nanoparticles released during grinding of exotic woods* 

Examples of measured values of concentrations and distributions of aerosol particles in the range 15 – 750 nm generated by grinding of exotic woods after subtraction of the

The comparison of the above-presented diagrams of the distribution of nanoparticles in the range 7 – 100 nm has shown a detailed distribution of aerosol particles of the Ipé, Jatoba and Massaranduba woods (that belong to the category of harder materials), with the maximum at ca. 40 nm, while for the Merbau, Bangkirai and Faveira woods the maximum value

The diagrams presented below (Figures 22 and 23) document that if we replace the grinding belt with a finer one the quantity of nanoparticles released into the atmosphere will increase,

The collected samples of sedimented dust after the wood grinding were subject to IR analysis, a microscopic study of the wood material and their thermal stability. The IR analysis sought to find a certain correlation between characteristic vibrations that may be related to the toxicity of the wood dust. The achieved microstructure of the dust was expected to provide information about the level of degradation of the wood structure by mechanical means (grinding). The thermal stability of the sedimented dust was expected to indicate the fire risks to be expected for the individual woods, while those results will be

Infrared spectroscopy is one of the few non-destructive methods for investigating the chemistry and physics of wood. Gradually, absorption bands with wave numbers have been

**Table 6.** Determination of quantities of ground-off woods

and the sizes of the particles will shift to lower values.

background are shown in the Figure 21.

shifted towards lower values.

*3.4.3. Analysis of sedimented dust:* 

published separately.

quantity (g)

Wood

(wood species)

**Figure 20.** Layout of the measuring technology in respect to the belt grinding machine:


In addition to the measurements of quantities and distribution of nano and micro aerosol particles we also measured the FIT factor to verify protective capacities of the respirators and collected samples of sedimented dust (sawdust).

## **3.4. Results and discussion**

## *3.4.1. Determination of quantities of grinded-off wood*

The weighted samples (mostly with the same area sizes) of exotic woods were grinded under the same conditions for 5 minutes on a belt grinding machine (see Figure 20). After the grinding was completed, the samples were weighed and the weight loss was converted into the area per 1 cm2. The results shown in Table 6 indicate that the highest weight loss was found for the wood Garapa, while the values for Massaranduba, Ipé and Teak were comparable. The wood most durable against the employed grinding method was Merbau. We also compared the quantities of ground-off wood material depending on the grit size of the grinding belts and we found out that finer surface resulted in a higher weight of the ground-off material by up to 20-25% .


**Table 6.** Determination of quantities of ground-off woods

434 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

**Figure 20.** Layout of the measuring technology in respect to the belt grinding machine:

c. measurements of distribution of aerosol (nano) particles, d) cascade impactor.

In addition to the measurements of quantities and distribution of nano and micro aerosol particles we also measured the FIT factor to verify protective capacities of the respirators

The weighted samples (mostly with the same area sizes) of exotic woods were grinded under the same conditions for 5 minutes on a belt grinding machine (see Figure 20). After the grinding was completed, the samples were weighed and the weight loss was converted into the area per 1 cm2. The results shown in Table 6 indicate that the highest weight loss was found for the wood Garapa, while the values for Massaranduba, Ipé and Teak were comparable. The wood most durable against the employed grinding method was Merbau. We also compared the quantities of ground-off wood material depending on the grit size of the grinding belts and we found out that finer surface resulted in a higher weight of the

b. measurements of distribution of aerosol particles (micro),

and collected samples of sedimented dust (sawdust).

*3.4.1. Determination of quantities of grinded-off wood* 

a. measurements of FIT factors,

**3.4. Results and discussion** 

ground-off material by up to 20-25% .

## *3.4.2. Distribution of nanoparticles released during grinding of exotic woods*

Examples of measured values of concentrations and distributions of aerosol particles in the range 15 – 750 nm generated by grinding of exotic woods after subtraction of the background are shown in the Figure 21.

The comparison of the above-presented diagrams of the distribution of nanoparticles in the range 7 – 100 nm has shown a detailed distribution of aerosol particles of the Ipé, Jatoba and Massaranduba woods (that belong to the category of harder materials), with the maximum at ca. 40 nm, while for the Merbau, Bangkirai and Faveira woods the maximum value shifted towards lower values.

The diagrams presented below (Figures 22 and 23) document that if we replace the grinding belt with a finer one the quantity of nanoparticles released into the atmosphere will increase, and the sizes of the particles will shift to lower values.

## *3.4.3. Analysis of sedimented dust:*

The collected samples of sedimented dust after the wood grinding were subject to IR analysis, a microscopic study of the wood material and their thermal stability. The IR analysis sought to find a certain correlation between characteristic vibrations that may be related to the toxicity of the wood dust. The achieved microstructure of the dust was expected to provide information about the level of degradation of the wood structure by mechanical means (grinding). The thermal stability of the sedimented dust was expected to indicate the fire risks to be expected for the individual woods, while those results will be published separately.

Infrared spectroscopy is one of the few non-destructive methods for investigating the chemistry and physics of wood. Gradually, absorption bands with wave numbers have been

defined that characterize the dominant building elements of the woods, such as cellulose, hemicellulose and lignin. We have also used the FT-IR (Fourier Transform Infrared) technology to measure infrared spectrums of the collected samples of sedimented dusts. Based on the published spectrums of similar woods and catalogue values of vibrations for the specific bonds and groups [7-10], we have made assignments to the individual absorption bands. As an example, we have made assignments to the measured values of the Massaranduba wood spectrum; see Table 7 and Figure 24.

Experiences with Anthropogenic Aerosol Spread in the Environment 437

**MASSARANDUBA**

**IPE**

10 100 1000 **Diameter of particles [nm]**

10 100 1000 **Diameter of particles [nm]**

a) b)

a) b)

Vibrations (cm-1) Assignment of the functional group or skeleton

1454 C-H deformation asymmetric -CH3 and –CH2–

1155 C-O-C vibration in cellulose and hemicelluloses

Massaranduba wood material. a) As a part of lignin, b) As a part of hemicellulose

814 Planar vibration of the mannose ring

2921 C-H valence bond in methyl group 1731 C=O ketone and in ester group 1593 Aromatic skeleton, valence bond C=O 1504 Aromatic skeleton, valence bond C=O

3343 O-H valence bond

894 Glycoside bonds

**Figure 23.** Distribution of aerosol particles of the Ipé wood a) grain size 80, b) grain size 100

1422 Vibration in the aromatic skeleton by combination with the deformation vibration in the C-H plane 1368 C-H deformation vibration in cellulose and hemicelluloses

1317 C-H vibration in cellulose and C-O vibration in syringyl derivatives 1232 Syringyla) skeleton and bond vibration C= in lignin and xylanb)

1023 Aromatic C-H deformation in the plane, C-OH, C-O deformation

**Table 7.** Assignment of the wave numbers of absorption belts to specific groups or skeleton of the

(Axis y: concentration of particles/cm3; axis x: diameter of particles [nm])

**Figure 22.** Distribution of aerosol particles of the Massaranduba wood a) grain size 80, b) grain size 100

**Concentration [N.cm-3]**

**Concentration [N.cm-3]**

**Figure 21.** Distribution of aerosol particles of the woods Ipé, Jatoba, Massaranduba, Merbau, Bangkirai and Faveira, released during their grinding

Experiences with Anthropogenic Aerosol Spread in the Environment 437

Massaranduba wood spectrum; see Table 7 and Figure 24.

defined that characterize the dominant building elements of the woods, such as cellulose, hemicellulose and lignin. We have also used the FT-IR (Fourier Transform Infrared) technology to measure infrared spectrums of the collected samples of sedimented dusts. Based on the published spectrums of similar woods and catalogue values of vibrations for the specific bonds and groups [7-10], we have made assignments to the individual absorption bands. As an example, we have made assignments to the measured values of the

**Figure 21.** Distribution of aerosol particles of the woods Ipé, Jatoba, Massaranduba, Merbau, Bangkirai

and Faveira, released during their grinding

**Figure 22.** Distribution of aerosol particles of the Massaranduba wood a) grain size 80, b) grain size 100 (Axis y: concentration of particles/cm3; axis x: diameter of particles [nm])

**Figure 23.** Distribution of aerosol particles of the Ipé wood a) grain size 80, b) grain size 100


**Table 7.** Assignment of the wave numbers of absorption belts to specific groups or skeleton of the Massaranduba wood material. a) As a part of lignin, b) As a part of hemicellulose

Experiences with Anthropogenic Aerosol Spread in the Environment 439

**particles** 

**Structure** 

coarse

fine

**Powderiness Size of** 

A summary overview of identifiable macroscopic properties is shown in Table 8

**cohesiveness** 

**Ipé** + ++ + ++ Coarse **Jatoba** ++ + ++ ++ Coarse **Massaranduba** ++ +++ ++ +++ Coarse **Merbau** +++ + +++ + Fine **Bangkirai** + ++ ++ ++ Medium

**Faveira** + +++ + ++ Medium

**Garapa** ++ + ++ + Coarse **Teak** + +++ + +++ Coarse **Bilinga** ++ ++ ++ ++ Coarse

We were interested in the shape of the particles, which will probably play a role in their fixation in the respiratory tract, so we made microscopic pictures. As an example shown below, we have provided microscopic pictures magnified 200 times, while the line segment

Other risks of nano-, micro- and dust particles are physicochemical, i.e. risk of fire, explosion, uncontrolled and undesired reaction. For this reason, the samples of sedimented dust were subject to thermal gravimetric analysis. For all samples of sedimented dust generated by coarse grinding, the thermal decomposition resulted in two separate exothermic processes T1 in the range 279-333 °C (the lowest for Merbau) and T2 in the range 402 -437 °C (the lowest for Garapa). After summarizing thermal processes during thermal decomposition of dusts of our woods, the highest thermal effects were found for the woods Jatoba (5904 kJ/kg) and Garapa (5506 kJ/kg), while the lowest value was found for the wood

Another finding with a safety impact was that if we use finer grains for the grinding of some woods, e.g. Massaranduba, the exothermic effect is much less significant – see the diagrams

We can thus conclude that, despite a modern extraction system that was installed in the workshop, the content of aerosol nanoparticles was two orders of magnitude higher than before the production works started, and the concentrations of dust particles in the immediate proximity of the grinder were several times higher than values permitted by Czech legislation. The sizes of aerosol nanoparticles, based on the determined distribution, mean that they can pass through protective barriers of the respiratory system up to the alveoli. Here the question remains on the role played in the toxicity by the concentration,

**Dustiness Inherent** 

**Table 8.** Description of macroscopic properties of sedimented particles

on the pictures represents 100 micrometers; see Figure 25.

chemical composition, surface and shape of the nanoparticles.

Teak (2210 kJ/kg ).

in Figure 26.

**Figure 24.** IR Spectrum of sedimented dust from Massaranduba wood

The comparison of the measured spectrums has shown a relative identity, particularly outside the fingerprint area of the molecule.

The variance in the wave number of C-OH vibrations is 15 cm-1 between the individual woods (the highest wave number 3350 cm-1 is for Ipé and Jatoba, the lowest is 3335 cm-1 for Bankirai). The variance of the valence bond vibration C-H is 72 cm-1 (the highest wave number is 2921 cm-1 for Massaranduba, the lowest is 2849 cm-1 for Bangkirai). The vibration shifts are probably caused by intermolecular hydrogen bonds that affect the wood density.

In the molecule fingerprint area, we focused on the identification of characteristic vibrations for various lignin skeletons and chinoid bonds (lapachol). The differences between the spectrums of the individual woods were demonstrated by absorbance values. Before the microscopic examination of the samples of sedimented dust (we will hereinafter use the term sawdust to refer to its method of origin) we described some of its external macroscopic properties and they were later confirmed at microscopic magnification by the factor of 40; they may be briefly described as follows:



A summary overview of identifiable macroscopic properties is shown in Table 8

**Figure 24.** IR Spectrum of sedimented dust from Massaranduba wood

outside the fingerprint area of the molecule.

they may be briefly described as follows:

or aggregation of sawdust


The comparison of the measured spectrums has shown a relative identity, particularly

The variance in the wave number of C-OH vibrations is 15 cm-1 between the individual woods (the highest wave number 3350 cm-1 is for Ipé and Jatoba, the lowest is 3335 cm-1 for Bankirai). The variance of the valence bond vibration C-H is 72 cm-1 (the highest wave number is 2921 cm-1 for Massaranduba, the lowest is 2849 cm-1 for Bangkirai). The vibration shifts are probably caused by intermolecular hydrogen bonds that affect the wood density.

In the molecule fingerprint area, we focused on the identification of characteristic vibrations for various lignin skeletons and chinoid bonds (lapachol). The differences between the spectrums of the individual woods were demonstrated by absorbance values. Before the microscopic examination of the samples of sedimented dust (we will hereinafter use the term sawdust to refer to its method of origin) we described some of its external macroscopic properties and they were later confirmed at microscopic magnification by the factor of 40;







We were interested in the shape of the particles, which will probably play a role in their fixation in the respiratory tract, so we made microscopic pictures. As an example shown below, we have provided microscopic pictures magnified 200 times, while the line segment on the pictures represents 100 micrometers; see Figure 25.

Other risks of nano-, micro- and dust particles are physicochemical, i.e. risk of fire, explosion, uncontrolled and undesired reaction. For this reason, the samples of sedimented dust were subject to thermal gravimetric analysis. For all samples of sedimented dust generated by coarse grinding, the thermal decomposition resulted in two separate exothermic processes T1 in the range 279-333 °C (the lowest for Merbau) and T2 in the range 402 -437 °C (the lowest for Garapa). After summarizing thermal processes during thermal decomposition of dusts of our woods, the highest thermal effects were found for the woods Jatoba (5904 kJ/kg) and Garapa (5506 kJ/kg), while the lowest value was found for the wood Teak (2210 kJ/kg ).

Another finding with a safety impact was that if we use finer grains for the grinding of some woods, e.g. Massaranduba, the exothermic effect is much less significant – see the diagrams in Figure 26.

We can thus conclude that, despite a modern extraction system that was installed in the workshop, the content of aerosol nanoparticles was two orders of magnitude higher than before the production works started, and the concentrations of dust particles in the immediate proximity of the grinder were several times higher than values permitted by Czech legislation. The sizes of aerosol nanoparticles, based on the determined distribution, mean that they can pass through protective barriers of the respiratory system up to the alveoli. Here the question remains on the role played in the toxicity by the concentration, chemical composition, surface and shape of the nanoparticles.

Ipé Jatoba

Experiences with Anthropogenic Aerosol Spread in the Environment 441

disruption of wood matter by technological operations means that one can anticipate different distributions of dominant wood components as well as low-molecular substances

a)

b) **Figure 26.** Thermal gravimetric analysis of sedimented dust generated with the grinding belt grain size

The differences in the size, shape, and certain physical properties of the particles of sedimented dust from the wood grinding have been described above. We can only speculate about the extent to which the shape of particles may influence their toxic effects. Sharp particles may behave in the organism similarly as has been described for asbestos

The size of the particles influences their shape, which we have illustrated with the shapes of particles generated by grinding Massaranduba and Jatoba woods. Figure 27 shows a comparison of microscopic pictures of particles with the size of hundreds of µm and particles with the size of units of µm, made by electron microscope, using particles trapped

on the surfaces of nanoparticles (microparticles).

80 (a) and 100 (b)

(pulmonary fibrosis) or chronic tracheitis.

between the levels A and B in the cascade impactor.

Massaranduba Merbau

100 µm

Apart from the dominant polymeric components of the woods (cellulose, hemicellulose, lignin), the woods also contain low-molecular substances. Those substances are sometimes classified as so-called extractable components, and they can be extracted from the wood material by various combinations of extraction agents.

Many of those substances, such as terpenoids, phenols, tannins, chinons, stylbens, flavonoids, alkaloids, etc., feature biological activity, both positive and negative. The disruption of wood matter by technological operations means that one can anticipate different distributions of dominant wood components as well as low-molecular substances on the surfaces of nanoparticles (microparticles).

440 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

Apart from the dominant polymeric components of the woods (cellulose, hemicellulose, lignin), the woods also contain low-molecular substances. Those substances are sometimes classified as so-called extractable components, and they can be extracted from the wood

Many of those substances, such as terpenoids, phenols, tannins, chinons, stylbens, flavonoids, alkaloids, etc., feature biological activity, both positive and negative. The

Ipé Jatoba

Massaranduba Merbau

Faveira Bangkirai

**Figure 25.** Microscopic pictures of sedimented dust after woods grinding

material by various combinations of extraction agents.

100 µm

**Figure 26.** Thermal gravimetric analysis of sedimented dust generated with the grinding belt grain size 80 (a) and 100 (b)

The differences in the size, shape, and certain physical properties of the particles of sedimented dust from the wood grinding have been described above. We can only speculate about the extent to which the shape of particles may influence their toxic effects. Sharp particles may behave in the organism similarly as has been described for asbestos (pulmonary fibrosis) or chronic tracheitis.

The size of the particles influences their shape, which we have illustrated with the shapes of particles generated by grinding Massaranduba and Jatoba woods. Figure 27 shows a comparison of microscopic pictures of particles with the size of hundreds of µm and particles with the size of units of µm, made by electron microscope, using particles trapped between the levels A and B in the cascade impactor.

Figure 28 shows electron microscope images of particles generated by grinding the Massaranduba wood trapped between A-C sorting levels in the cascade impactor for the Jatoba wood.

Experiences with Anthropogenic Aerosol Spread in the Environment 443

**Figure 27.** Comparison of the shape and size of Massaranduba wood particles

should take into account the character (type) of the processed wood.

A general conclusion can be drawn that the world´s major occupational health agencies only provide warnings about the risks in their reports for selected individual types of wood, and they request better protection of particular body parts (skin, eye mucosa, respiratory tract).

Our measurements have led to a recommendation that the selection of safety measures to protect the health of the employees during some technological operations with woods

1 mm

Experiences with Anthropogenic Aerosol Spread in the Environment 443

442 Atmospheric Aerosols – Regional Characteristics – Chemistry and Physics

Jatoba wood.

Figure 28 shows electron microscope images of particles generated by grinding the Massaranduba wood trapped between A-C sorting levels in the cascade impactor for the

1 mm

100 µm

**Figure 27.** Comparison of the shape and size of Massaranduba wood particles

A general conclusion can be drawn that the world´s major occupational health agencies only provide warnings about the risks in their reports for selected individual types of wood, and they request better protection of particular body parts (skin, eye mucosa, respiratory tract).

Our measurements have led to a recommendation that the selection of safety measures to protect the health of the employees during some technological operations with woods should take into account the character (type) of the processed wood.

Sorting level A Sorting level B

Experiences with Anthropogenic Aerosol Spread in the Environment 445

Thanks to the pro-active approach of the company EVRAZ Vítkovice Steel, a.s. to the environment and safety of their employees, we were able to perform measurements of quantities and distribution of aerosols during the operation in various parts of the

The basis of the oxygen steelmaking (i.e. oxidation) is the removal of undesired impurities from the raw iron melt. The key elements that are converted into oxides in the process are

The oxygen steelmaking process is discontinuous and may be divided into the following

b. Pre-treatment of the metal melt (desulfurization of the melt by introduction of calcium

Before the experimental measurement, we attempted to identify locations with the expected

Meanwhile, we had to consider the safety of the workers performing the measurements and sensitivity of the employed technology to the environment in which it operates, e.g. high

The selected locations in the premises of continual steel casting and in the converter hall of

Measurements were conducted under regular operation of the steelworks. For safety reasons, measuring instruments to measure quantities and distribution of aerosol

a. at the equipment for continual casting, ca. 3 m from the slab, which had been already in the horizontal position and in the area of the so-called secondary cooling, ca. 6 m from

b. in the steelworks dispatching section, ca. 3 m from the scarfing machine, where the

steelworks that utilize oxygen steelmaking.

a. Preparation and storage of metal melt

carbide, magnesium and lime) c. Oxidation in the oxygen converter

increased emission levels, specifically:


temperature, explosive environment, etc.


the steelworks represented the resulting compromise.

nanoparticles were situated only in the following locations:

the flame-cutting machine (Figure 29).

cooled slab was parted crosswise (Figure 30).

e. Casting (slab casting)



**3.6. Experimental part** 

steps:

carbon, silicon, manganese, phosphor and sulphur.

d. Secondary metallurgy (i.e. vacuum metallurgy)

Sorting level C

**Figure 28.** Electron microscope pictures of Jatoba wood particles generated by grinding.

Based on the available toxicological information about a particular wood, or based on measurements similar to those we have made for the anticipated technological operation, it will be necessary to specify or to expand the preventive measures with the objective of minimizing the contact of workers with particles generated by the processing. The measures may include technical (e.g. wetting system) and organizational measures (e.g. shorter exposure, alternation of workers), personal protective equipment (e.g. HEPA respirators: our measurements have demonstrated their 93-97% effectiveness) or health related measures (e.g. shortened intervals between medical checkups).
